Steel bar tying machine

Abstract

The present invention provides a technique capable of performing operations corresponding to the diameter of a steel bar without providing a discrimination mechanism for discriminating the diameter of the steel bar. This specification discloses a steel bar bundling machine. The steel bar bundling machine may include: a feeding motor; a current sensor that detects the current flowing in the feeding motor; and a control unit that controls the operation of the feeding motor. The steel bar bundling machine may be capable of performing the following processes: a feeding process of feeding a steel wire around the steel bar by driving the feeding motor; a gripping process of gripping near the front end of the steel wire; a pulling-back process of pulling back the steel wire by driving the feeding motor; a cutting process of cutting the steel wire; and a twisting process of twisting the steel wire. The control unit may be configured to discriminate the diameter of the steel bar based on the historical value of the current value flowing in the feeding motor during the pulling-back process.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a steel bar bundling machine. Background Art

[0002] A steel bar bundling machine is disclosed in Patent Document 1. The steel bar bundling machine includes a feeding motor, a current sensor that detects the current flowing in the feeding motor, a control unit that controls the operation of the feeding motor, and a discrimination mechanism that discriminates the diameter of the steel bar. The steel bar bundling machine can perform a feeding process of feeding a steel wire around the steel bar by driving the feeding motor, a cutting process of cutting the steel wire, and a twisting process of twisting the steel wire. The steel bar bundling machine performs operations corresponding to the diameter of the steel bar discriminated by the discrimination mechanism.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open No. 2001-140471 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the above-described steel bar bundling machine, it is necessary to provide a discrimination mechanism for discriminating the diameter of the steel bar, and the mechanical structure is complicated. In this specification, a technology is provided in a steel bar bundling machine that can perform operations corresponding to the diameter of the steel bar without providing a discrimination mechanism for discriminating the diameter of the steel bar.

[0008] Solutions for Solving the Problems

[0009] This specification discloses a steel bar bundling machine. The steel bar bundling machine may include: a feeding motor; a current sensor that detects the current flowing in the feeding motor; and a control unit that controls the operation of the feeding motor. The steel bar bundling machine may be capable of performing the following processes: a feeding process of feeding a steel wire around the steel bar by driving the feeding motor; a holding process of holding near the front end of the steel wire; a pulling-back process of pulling back the steel wire by driving the feeding motor; a cutting process of cutting the steel wire; and a twisting process of twisting the steel wire. The control unit may be configured to discriminate the diameter of the steel bar based on the historical value of the current value flowing in the feeding motor during the pulling-back process.

[0010] This specification also discloses another steel bar bundling machine. The steel bar bundling machine may include: a feeding motor; a current sensor that detects the current flowing in the feeding motor; and a control unit that controls the operation of the feeding motor. The steel bar bundling machine may be capable of performing the following processes: a feeding process of feeding a steel wire around a steel bar by driving the feeding motor; a holding process of holding near the front end of the steel wire; a pulling-back process of pulling back the steel wire by driving the feeding motor; a cutting process of cutting the steel wire; and a twisting process of twisting the steel wire. The control unit may be configured to stop the feeding motor when a stop condition is satisfied during the pulling-back process. The control unit may be configured to change the stop condition corresponding to the historical value of the current value flowing in the feeding motor during the pulling-back process. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a perspective view of the steel bar bundling machine 2 of the embodiment.

[0012] Figure 2 is a side view showing the internal structure of the steel bar bundling machine 2 of the embodiment.

[0013] Figure 3 is a perspective view of the feeding mechanism 24 of the steel bar bundling machine 2 of the embodiment.

[0014] Figure 4 is a cross-sectional view near the guiding mechanism 26 of the steel bar bundling machine 2 of the embodiment.

[0015] Figure 5 is a side view of the holding part 82 and the cutting mechanism 28 in a state where the operated member 72 of the steel bar bundling machine 2 of the embodiment is in the initial position.

[0016] Figure 6 is a side view of the holding part 82 and the cutting mechanism 28 in a state where the operated member 72 of the steel bar bundling machine 2 of the embodiment is in the cutting position.

[0017] Figure 7 is a perspective view of the twisting mechanism 30 of the steel bar bundling machine 2 of the embodiment.

[0018] Figure 8 is a top view of the screw shaft 84, the clamp guide 86, the clamping member 90, and the biasing member 92 of the steel bar bundling machine 2 of the embodiment.

[0019] Figure 9 is a sectional perspective view of the holding part 82 in a state where the outer sleeve 102 of the steel bar bundling machine 2 of the embodiment is in the advanced position relative to the clamp guide 86.

[0020] Figure 10It is a top view of the upper clamping member 114 of the steel bar bundling machine 2 according to the embodiment.

[0021] Figure 11 It is a top view of the lower clamping member 116 of the steel bar bundling machine 2 according to the embodiment.

[0022] Figure 12 It is a front view of the clamping member 90 of the steel bar bundling machine 2 according to the embodiment.

[0023] Figure 13 It is a sectional perspective view of the clamping member 90 and the guide pin 110 in a state where the guide pin 110 in the steel bar bundling machine 2 according to the embodiment is in the middle position between the upper guide hole 118a and the lower guide hole 126a.

[0024] Figure 14 It is a sectional perspective view of the clamping member 90 and the guide pin 110 in a state where the guide pin 110 in the steel bar bundling machine 2 according to the embodiment is at the rear of the upper guide hole 118a and the lower guide hole 126a.

[0025] Figure 15 It is a perspective view of the rotation restricting portion 150 of the steel bar bundling machine 2 according to the embodiment.

[0026] Figure 16 It is a sectional perspective view of the holding portion 82 in a state where the stepped portion 102a of the outer sleeve 102 in the steel bar bundling machine 2 according to the embodiment abuts against the stepped portion 86c of the jig guide 86.

[0027] Figure 17 It is a side view of the holding portion 82 and the rotation restricting portion 150 in a state where the base member 152 and the biasing members 162, 164 are removed from the steel bar bundling machine 2 according to the embodiment.

[0028] Figure 18 It is an exploded perspective view of the feed motor 32 and the twisting motor 76 of the steel bar bundling machine 2 according to the embodiment.

[0029] Figure 19 It is a front view of the stators 174, 186 of the feed motor 32 and the twisting motor 76 and the sensor substrates 178, 190 of the steel bar bundling machine 2 according to the embodiment.

[0030] Figure 20 It is a diagram showing the circuit structure of the control board 20 of the steel bar bundling machine 2 according to the embodiment.

[0031] Figure 21 It is a diagram showing an example of the circuit structure of the inverting circuits 212, 214 of the steel bar bundling machine 2 according to the embodiment.

[0032] Figure 22This is a diagram showing an example of the circuit structure of the motor control signal output destination switching circuit 204 of the steel bar bundling machine 2 according to the embodiment.

[0033] Figure 23 This is a diagram showing another example of the circuit structure of the motor control signal output destination switching circuit 204 of the steel bar bundling machine 2 according to the embodiment.

[0034] Figure 24 This is a diagram showing yet another example of the circuit structure of the motor control signal output destination switching circuit 204 of the steel bar bundling machine 2 according to the embodiment.

[0035] Figure 25 This is a diagram showing an example of the circuit structure of the braking circuits 218 and 220 of the steel bar bundling machine 2 according to the embodiment.

[0036] Figure 26 This is a diagram showing an example of the circuit structure of the motor rotation signal input source switching circuit 206 of the steel bar bundling machine 2 according to the embodiment.

[0037] Figure 27 This is a diagram showing another example of the circuit structure of the motor rotation signal input source switching circuit 206 of the steel bar bundling machine 2 according to the embodiment.

[0038] Figure 28 This is a diagram showing yet another example of the circuit structure of the motor rotation signal input source switching circuit 206 of the steel bar bundling machine 2 according to the embodiment.

[0039] Figure 29 This is a flowchart of the processing performed by the MCU 202 of the steel bar bundling machine 2 according to the embodiment.

[0040] Figure 30 This shows Figure 29 a flowchart of the details of the first driving process of the feeding motor in S2.

[0041] Figure 31 This shows Figure 29 a flowchart of the details of the first driving process of the twisting motor in S4.

[0042] Figure 32 This shows Figure 29 a flowchart of the details of the second driving process of the feeding motor in S6.

[0043] Figure 33 This is a graph showing an example of the change over time of the current value I flowing through the feeding motor 32 during the pulling-back process of the steel bar bundling machine 2 according to the embodiment.

[0044] Figure 34It is a diagram schematically showing the relationship between the wire W and the reinforcing bar R in the case of a relatively large diameter of the reinforcing bar and a relatively small diameter of the reinforcing bar during the pulling-back process of the reinforcing bar bundling machine 2 in the embodiment.

[0045] Figure 35 It shows Figure 29 a flowchart of the detailed situation of the second driving process of the stranding motor of S8.

[0046] Figure 36 It shows Figure 29 a flowchart of the detailed situation of the third driving process of the stranding motor of S10.

[0047] Explanation of Reference Numerals

[0048] 2. Steel bar tying machine; 4. Main body; 6. Handle; 8. Trigger; 9. Trigger switch; 10. Battery installation part; 12. Reel holder; 12a. Storage space; 12b. Display part; 12c. Operation part; 14. Holder housing; 14a. Rotating shaft; 16. Cover member; 18. Reel; 20. Control board; 22. Display board; 22a. Setting display LED; 22b. Setting switch; 24. Feeding mechanism; 26. Guiding mechanism; 28. Cutting mechanism; 30. Twisting mechanism; 32. Feeding motor; 34. Reduction part; 36. Feeding part; 38. Base member; 40. Guiding member; 40a. Guiding hole; 42. Driving gear; 44. First gear; 44a. Groove; 46. Second gear; 46a. Groove; 48. Gear support member; 48a. Swing shaft; 52. Biasing member; 56. Wire guide; 56a. Protrusion; 58. Upper guiding arm; 58a. Upper guiding path; 60. Lower guiding arm; 60a. Lower guiding path; 61. First guiding pin; 62. Second guiding pin; 66. Cutting member; 66a. Rotating shaft; 68. Link part; 70. Connecting member; 72. Operated member; 72a. Rotating shaft; 72b. Tab; 74. Biasing member; 76. Twisting motor; 78. Reduction part; 82. Holding part; 84. Screw shaft; 84a. Thick diameter part; 84b. Thin diameter part; 84c. Ball groove; 84d. Engagement groove; 86. Clamp guide; 86a. Recess; 86b. Engagement pin; 86c. Step part; 88. Sleeve; 90. Clamping member; 92. Biasing member; 94. Ball; 96. Washer; 100. Inner sleeve; 100a. Rib; 102. Outer sleeve; 102a. Step part; 104. Support member; 106. Fixing screw; 110. Guiding pin; 114. Upper clamping member; 116. Lower clamping member; 118. Upper base; 118a. Upper guiding hole; 120. First upper protrusion; 121. Upper connecting part; 122. Second upper protrusion; 123. First anti - detachment part; 124. First wire path; 126. Lower base; 126a. Lower guiding hole; 128. First lower protrusion; 129. Lower connecting part; 130. Second lower protrusion; 131. Second anti - detachment part; 132. Second wire path; 134. Auxiliary path; 136. Initial state detection sensor; 138. Grasp detection sensor; 140. Pusher plate; 140a. Initial state detection magnet; 140b. Grasp detection magnet; 144. Fin; 146. Short fin; 148. Long fin; 150. Rotation limiting part; 152. Base member; 154. Upper stopper; 154a. Limiting part; 156. Lower stopper; 156a. Limiting part; 158. Swing shaft; 160. Swing shaft; 162. Biasing member; 164. Biasing member; 170. Coil; 172. Tooth part; 174. Stator; 176. Rotor; 178. Sensor board; 180. Hall sensor180a, the first Hall element; 180b, the second Hall element; 180c, the third Hall element; 182, coil; 184, tooth portion; 186, stator; 188, rotor; 190, sensor substrate; 192, Hall sensor; 192a, the first Hall element; 192b, the second Hall element; 192c, the third Hall element; 200, control power supply circuit; 202a, motor control signal output port; 202b, motor rotation signal input port; 202c, general input / output port; 204, motor control signal output destination switching circuit; 206, motor rotation signal input source switching circuit; 208, gate drive circuit; 210, gate drive circuit; 212, inverter circuit; 214, inverter circuit; 216, current detection circuit; 218, braking circuit; 220, braking circuit; 222a, switching element; 222b, switching element; 224a, switching element; 224b, switching element; 226a, switching element; 226b, switching element; 228, positive-side potential line; 230, negative-side potential line; 232, motor power line; 234, motor power line; 236, motor power line; 238a, switching element; 238b, switching element; 240a, switching element; 240b, switching element; 242a, switching element; 242b, switching element; 244, positive-side potential line; 246, negative-side potential line; 248, motor power line; 250, motor power line; 252, motor power line; 260, multiplexer; 262, FET; 264, FET; 266, NOT gate; 268, NOR gate; 270, NOR gate; 272, NOT gate; 274, NOT gate; 274a, transistor; 274b, transistor; 274c, transistor; 274d, transistor; 276a, resistor; 276b, resistor; 276c, resistor; 276d, resistor; 276e, resistor; 276f, resistor; 276g, resistor; 276h, resistor; 278a, transistor; 278b, transistor; 278c, transistor; 278d, transistor; 280a, resistor; 280b, resistor; 280c, resistor; 280d, resistor; 280e, resistor; 280f, resistor; 280g, resistor; 280h, resistor; 282, multiplexer; 284, FET; 286, FET; 288, NOT gate; 290, NOR gate; 292, NOR gate; 294, NOR gate; 296, NOT gate.; Detailed implementation manner

[0049] The following describes in detail representative and non-limiting specific examples of the present invention with reference to the accompanying drawings. This detailed description is merely intended to show those skilled in the art the details of the preferred examples for implementing the present invention and is not intended to limit the scope of the present invention. In addition, in order to provide a further improved steel bar bundling machine, the additional features and technical solutions disclosed can be used separately from other features and technical solutions or used together with other features and technical solutions.

[0050] In addition, the combination of features and processes disclosed in the following detailed description is not necessary in the broadest sense when implementing the present invention and is only described to specifically illustrate representative specific examples of the present invention. Furthermore, when providing additional and useful embodiments of the present invention, the various features of the following representative specific examples and the various features recited in the claims do not have to be combined as in the specific examples described herein or in the recited order.

[0051] All features recited in this specification and / or claims are intended to be separately and independently disclosed as limitations on the specific matters recited in the original application disclosure and claims, separate from the structure of the features recited in the embodiments and / or claims. Furthermore, all numerical ranges and descriptions related to an organization or group are made with the intention of disclosing the intermediate structure as limitations on the specific matters recited in the original application disclosure and claims.

[0052] In one or more embodiments, a steel bar bundling machine may include: a feeding motor; a current sensor that detects the current flowing in the feeding motor; and a control unit that controls the operation of the feeding motor. The steel bar bundling machine may be capable of performing the following processes: a feeding process of feeding a steel wire around a steel bar by driving the feeding motor; a gripping process of gripping near the front end of the steel wire; a pulling-back process of pulling back the steel wire by driving the feeding motor; a cutting process of cutting the steel wire; and a twisting process of twisting the steel wire. The control unit may be configured to determine the diameter of the steel bar based on the historical value of the current value flowing in the feeding motor during the pulling-back process.

[0053] In the above-described pulling-back process, the steel wire sent around the steel bar is reduced in diameter and closely adheres to the steel bar. At this time, the characteristics of the current value flowing in the feeding motor change at the timing when the steel wire starts to closely adhere to the steel bar and at the timing when the steel wire finishes closely adhering to the steel bar. When the diameter of the steel bar is large, the timing when the steel wire starts to closely adhere to the steel bar and the timing when the steel wire finishes closely adhering to the steel bar are earlier. On the contrary, when the diameter of the steel bar is small, the timing when the steel wire starts to closely adhere to the steel bar and the timing when the steel wire finishes closely adhering to the steel bar are later. In the above-described steel bar bundling machine, focusing on the fact that the characteristics of the current value flowing in the feeding motor in the pulling-back process of the steel wire are different according to the diameter of the steel bar, the diameter of the steel bar is determined based on the historical value of the current value flowing in the feeding motor. By adopting such a structure, it is possible to perform operations corresponding to the diameter of the steel bar without providing a determination mechanism for determining the diameter of the steel bar.

[0054] In one or more embodiments, the control unit may also be configured to calculate the time change rate of the current value flowing in the feeding motor after exceeding the peak value of the starting current in the pulling-back process, and determine the diameter of the steel bar based on the timing when the time change rate reaches the time change rate threshold.

[0055] In the pulling-back process, the current value flowing in the feeding motor gradually decreases after increasing to the peak value of the starting current. After that, the current value flowing in the feeding motor changes from decreasing to increasing at the timing when the steel wire starts to closely adhere to the steel bar, and changes from increasing to decreasing again at the timing when the steel wire finishes closely adhering to the steel bar. According to the above structure, at the timing when the current value flowing in the feeding motor changes from decreasing to increasing after exceeding the peak value of the starting current, that is, at the timing when the steel wire starts to closely adhere to the steel bar, the diameter of the steel bar can be determined. By adopting such a structure, it is possible to perform the operations in the latter half of the pulling-back process corresponding to the determined diameter of the steel bar.

[0056] In one or more embodiments, the control unit may also be configured to stop the feeding motor when a stop condition is satisfied in the pulling-back process. The control unit may also be configured to change the stop condition corresponding to the determined diameter of the steel bar.

[0057] In the pulling-back process, when the diameter of the steel bar is large, since the timing when the steel wire finishes closely adhering to the steel bar is earlier, it is necessary to stop the feeding motor correspondingly earlier. On the contrary, when the diameter of the steel bar is small, the timing when the steel wire finishes closely adhering to the steel bar is later, and it is necessary to stop the feeding motor correspondingly later. According to the above structure, since the stop condition is changed corresponding to the determined diameter of the steel bar, it is possible to stop the feeding motor at an appropriate timing.

[0058] In one or more embodiments, the control unit may also be configured to, in the pulling-back process, determine the minimum value of the current flowing in the feeding motor after the peak value of the starting current of the feeding motor is exceeded, and calculate the increase amount of the current value flowing in the feeding motor relative to the minimum value. The stop condition may include the condition that the increase amount reaches an increase amount threshold. The control unit may also be configured to change the increase amount threshold according to the determined diameter of the steel bar.

[0059] In the pulling-back process, when the diameter of the steel bar is relatively large, since the wire starts to closely adhere to the steel bar at an earlier time, the current value flowing in the feeding motor does not decrease significantly after exceeding the peak value of the starting current. Therefore, the minimum value of the current value flowing in the feeding motor after exceeding the peak value of the starting current is relatively large, and the increase amount of the current value until the wire completes the close adhesion to the steel bar is small. On the contrary, when the diameter of the steel bar is relatively small, since the wire starts to closely adhere to the steel bar at a later time, the current value flowing in the feeding motor decreases significantly after exceeding the peak value of the starting current. Therefore, the minimum value of the current value flowing in the feeding motor after exceeding the peak value of the starting current is relatively small, and the increase amount of the current value until the wire completes the close adhesion to the steel bar is large. According to the above structure, since the increase amount threshold is changed according to the determined diameter of the steel bar, the feeding motor can be stopped at an appropriate time.

[0060] In one or more embodiments, the steel bar tying machine may also include: a feeding motor; a current sensor that detects the current flowing in the feeding motor; and a control unit that controls the operation of the feeding motor. The steel bar tying machine may be capable of performing the following processes: a feeding process of feeding a wire around a steel bar by driving the feeding motor; a holding process of holding near the front end of the wire; a pulling-back process of pulling back the wire by driving the feeding motor; a cutting process of cutting the wire; and a twisting process of twisting the wire. The control unit may also be configured to stop the feeding motor when a stop condition is satisfied in the pulling-back process. The control unit may also be configured to change the stop condition according to the historical value of the current value flowing in the feeding motor in the pulling-back process.

[0061] In the above steel bar tying machine, focusing on the fact that the characteristics of the current value flowing in the feeding motor in the wire pulling-back process are different according to the diameter of the steel bar, the stop condition of the feeding motor is changed based on the historical value of the current value flowing in the feeding motor. By adopting such a structure, actions corresponding to the diameter of the steel bar can be performed without providing a discrimination mechanism for discriminating the diameter of the steel bar.

[0062] In one or more embodiments, the control unit may also be configured to, during the pulling-back process, calculate the rate of change of the current value flowing through the feeding motor after exceeding the peak value of the starting current of the feeding motor, and change the stop condition in correspondence with the timing when the rate of change of time reaches a rate-of-change threshold.

[0063] According to the above structure, at the timing when the current value flowing through the feeding motor changes from decreasing to increasing after exceeding the peak value of the starting current, that is, at the timing when the steel wire starts to closely adhere to the steel bar, the stop condition of the feeding motor can be changed.

[0064] In one or more embodiments, the control unit may also be configured to, during the pulling-back process, determine the minimum value of the current value flowing through the feeding motor after exceeding the peak value of the starting current of the feeding motor, and calculate the increase amount of the current value flowing through the feeding motor relative to the minimum value. The stop condition may include the condition that the increase amount reaches an increase-amount threshold. The control unit may also be configured to change the increase-amount threshold in correspondence with the timing when the rate of change of time reaches the rate-of-change threshold.

[0065] According to the above structure, since the increase-amount threshold is changed in correspondence with the timing when the rate of change of the current value flowing through the feeding motor reaches the rate-of-change threshold, the feeding motor can be stopped at an appropriate timing.

[0066] (Example)

[0067] As Figure 1 shown, the steel-bar bundling machine 2 is a steel-bar bundling machine that bundles a plurality of steel bars R using a steel wire W. For example, the steel-bar bundling machine 2 can bundle small-diameter steel bars R with a diameter less than 15 mm (for example, a diameter of 10 mm or 13 mm), medium-diameter steel bars R with a diameter greater than or equal to 15 mm and less than 25 mm (for example, a diameter of 16 mm or 22 mm), and large-diameter steel bars R with a diameter greater than or equal to 25 mm (for example, a diameter of 25 mm or 32 mm). The diameter of the steel wire W is, for example, a value between 0.5 mm and 2.0 mm.

[0068] The steel-bar bundling machine 2 includes a main body 4, a handle 6, a battery mounting portion 10, a battery B, and a reel holder 12. The handle 6 is a member for an operator to hold. The handle 6 is provided at the lower rear side of the main body 4. The handle 6 is integrally formed with the main body 4. A trigger 8 is mounted on the upper front side of the handle 6. A trigger switch 9 for detecting whether the trigger 8 is pushed in is housed inside the handle 6 (refer to Figure 2)。The battery mounting portion 10 is provided at the lower part of the handle 6. The battery mounting portion 10 is integrally formed with the handle 6. The battery B is detachably mounted on the battery mounting portion 10. The battery B is, for example, a lithium ion battery. The reel holder 12 is disposed below the main body 4. The reel holder 12 is disposed at a position forward of the handle 6. In addition, in the present embodiment, the longitudinal direction of the twisting mechanism 30 described later is referred to as the front-rear direction, the direction orthogonal to the front-rear direction is referred to as the up-down direction, and the direction orthogonal to the front-rear direction and the up-down direction is referred to as the left-right direction.

[0069] The reel holder 12 includes a holder housing 14 and a cover member 16. The holder housing 14 is mounted on the lower front side of the main body 4 and the front portion of the battery mounting portion 10. The cover member 16 is mounted on the holder housing 14 so as to be rotatable about a rotation shaft 14a at the lower part of the holder housing 14. The storage space 12a is defined by the holder housing 14 and the cover member 16 (see Figure 2 ). The reel 18 around which the wire rope W is wound is disposed in the storage space 12a. That is, the reel holder 12 houses the reel 18 therein.

[0070] A display portion 12b and an operation portion 12c are provided on the rear surface of the reel holder 12. The operation portion 12c receives operations from the user related to various settings such as the bundling force of the steel bar bundling machine 2. The display portion 12b can display information related to the current settings of the steel bar bundling machine 2.

[0071] As Figure 2 shown, the steel bar bundling machine 2 includes a control board 20 and a display board 22. The control board 20 is housed in the battery mounting portion 10. The control board 20 controls the operation of the steel bar bundling machine 2. The display board 22 is housed in the rear portion of the reel holder 12. The display board 22 is connected to the control board 20 by wiring (not shown). The display board 22 includes a setting display LED 22a that emits light toward the display portion 12b (see Figure 20 ) and a setting switch 22b that detects operations performed by the user on the operation portion 12c (see Figure 20 ).

[0072] The wire bundling machine 2 includes a feeding mechanism 24, a guiding mechanism 26, a cutting mechanism 28, and a twisting mechanism 30. The feeding mechanism 24 is housed in the front lower part of the main body 4. The feeding mechanism 24 performs a feeding action of sending out the steel wire W to the guiding mechanism 26 and a pulling-back action of pulling back the steel wire W from the guiding mechanism 26. The guiding mechanism 26 is arranged at the front part of the main body 4. The guiding mechanism 26 guides the steel wire W sent out from the feeding mechanism 24 in a circular shape around the steel bar R. The cutting mechanism 28 is housed in the lower part of the main body 4. The cutting mechanism 28 performs a cutting action of cutting the steel wire W wound around the steel bar R. The twisting mechanism 30 is housed in the main body 4. The twisting mechanism 30 performs a twisting action of twisting the steel wire W around the steel bar R.

[0073] (Structure of the feeding mechanism 24)

[0074] As Figure 3 shown, the feeding mechanism 24 includes a feeding motor 32, a reduction part 34, and a feeding part 36. The feeding motor 32 is connected to the control substrate 20 by wiring (not shown). The feeding motor 32 is driven by the electric power supplied from the battery B. The feeding motor 32 is controlled by the control substrate 20. The feeding motor 32 is connected to the drive gear 42 of the feeding part 36 through the reduction part 34. The reduction part 34 reduces the rotation of the feeding motor 32, for example, by using a planetary gear mechanism, and transmits it to the drive gear 42.

[0075] In this embodiment, the feeding motor 32 is a brushless motor. As Figure 18 shown, the feeding motor 32 includes a stator 174 having a tooth part 172 wound with a coil 170, a rotor 176 arranged inside the stator 174, and a sensor substrate 178 fixed to the stator 174. The stator 174 is made of a magnetic material. The rotor 176 has a permanent magnet with magnetic poles arranged in the circumferential direction. As Figure 19 shown, a Hall sensor 180 is provided on the sensor substrate 178. The Hall sensor 180 includes a first Hall element 180a, a second Hall element 180b, and a third Hall element 180c. The first Hall element 180a, the second Hall element 180b, and the third Hall element 180c detect the magnetic force from the rotor 176. The Hall sensor 180 is arranged on the sensor substrate 178 at a position where the electrical angle is 25° ahead with respect to the forward rotation of the feeding motor 32 and the electrical angle is 25° behind with respect to the reverse rotation of the feeding motor 32. In addition, in this embodiment, the control substrate 20 outputs the patterns staggered by one stage every electrical angle of 60° with respect to the reverse rotation of the feeding motor 32. Therefore, it is controlled with a 25° lead angle with respect to the forward rotation of the feeding motor 32 and a 35° lead angle of 60° - 25° with respect to the reverse rotation of the feeding motor 32.

[0076] As Figure 3 shown, the feeding unit 36 includes a base member 38, a guide member 40, a drive gear 42, a first gear 44, a second gear 46, a gear support member 48, and a biasing member 52. The guide member 40 is fixed to the base member 38. The guide member 40 has a guide hole 40a. The guide hole 40a has a tapered shape with a wider lower end and a narrower upper end. A wire W passes through the guide hole 40a.

[0077] The drive gear 42 is connected to the reduction unit 34. The first gear 44 is rotatably supported by the base member 38. The first gear 44 meshes with the drive gear 42. The first gear 44 rotates by the rotation of the drive gear 42. The first gear 44 has a groove 44a. The groove 44a is formed on the outer peripheral surface of the first gear 44 in a direction along the rotation direction of the first gear 44. The second gear 46 meshes with the first gear 44. The second gear 46 is rotatably supported by the gear support member 48. The second gear 46 has a groove 46a. The groove 46a is formed on the outer peripheral surface of the second gear 46 in a direction along the rotation direction of the second gear 46. The gear support member 48 is swingably supported by the base member 38 via a swing shaft 48a. The biasing member 52 biases the gear support member 48 in a direction in which the second gear 46 approaches the first gear 44. As a result, the second gear 46 is pressed against the first gear 44. As a result, the wire W is clamped between the groove 44a of the first gear 44 and the groove 46a of the second gear 46. When the gear support member 48 is pushed in against the acting force of the biasing member 52, the second gear 46 separates from the first gear 44. Thus, when replacing the reel 18, the wire W can be easily inserted between the groove 44a of the first gear 44 and the groove 46a of the second gear 46.

[0078] When the feeding motor 32 rotates in a state where the wire W is clamped between the groove 44a of the first gear 44 and the groove 46a of the second gear 46, the wire W is moved. In the present embodiment, when the feeding motor 32 rotates in the reverse direction, the drive gear 42 rotates in the Figure 3 direction D1 shown, and the wire W is sent out toward the guide mechanism 26. When the feeding motor 32 rotates in the forward direction, the drive gear 42 rotates in the Figure 3 direction D2 shown, and the wire W is pulled back from the guide mechanism 26.

[0079] (Structure of the guide mechanism 26)

[0080] As Figure 4 shown, the guide mechanism 26 includes a wire guide 56, an upper guide arm 58, and a lower guide arm 60. The wire W after being sent out from the feeding mechanism 24 passes through the inside of the wire guide 56. A protrusion 56a is formed inside the wire guide 56.

[0081] The upper guide arm 58 is provided at the upper front part of the main body 4. The upper guide arm 58 has an upper guide passage 58a. The wire W that has passed through the inside of the wire guide 56 passes through the upper guide passage 58a. A first guide pin 61 and a second guide pin 62 are arranged in the upper guide passage 58a. When the wire W passes through the upper guide passage 58a in contact with the protruding portion 56a of the wire guide 56, the first guide pin 61 and the second guide pin 62, a downward curling tendency is imparted to the wire W.

[0082] The lower guide arm 60 is provided at the lower front part of the main body 4. The lower guide arm 60 has a lower guide passage 60a. The wire W that has passed through the upper guide passage 58a passes through the lower guide passage 60a. Figure 4 In the figure, the part of the wire W that is blocked from view by the lower guide arm 60 and the stranding mechanism 30 is shown by a dotted line.

[0083] (Structure of the cutting mechanism 28)

[0084] As Figure 5 shown, the cutting mechanism 28 includes a cutting member 66 and a link portion 68. The cutting member 66 is a member for cutting the wire W. As Figure 4 shown, the cutting member 66 is arranged on the path through which the wire W sent from the feeding mechanism 24 to the guiding mechanism 26 passes. The wire W passes through the inside of the cutting member 66. The cutting member 66 is supported by the main body 4 so as to be rotatable about a rotation axis 66a (see Figure 5 ). When the cutting member 66 rotates in the direction D3 as Figure 4 shown, the wire W is cut by the cutting member 66.

[0085] As Figure 5 shown, the link portion 68 includes a connecting member 70, an operated member 72, and a biasing member 74. The connecting member 70 connects the cutting member 66 and the operated member 72. The operated member 72 is supported by the main body 4 so as to be rotatable about a rotation axis 72a. The operated member 72 is biased by the biasing member 74 to be in an initial position in a normal state. When a force greater than the acting force of the biasing member 74 is applied to the operated member 72, the operated member 72 rotates about the rotation axis 72a. As a result, the connecting member 70 moves forward, and the cutting member 66 rotates about the rotation axis 66a. When the operated member 72 rotates from the initial position about the rotation axis 72a to the Figure 6 shown predetermined position, the wire W is cut by the rotation of the cutting member 66. Hereinafter, the position of the operated member 72 in the foregoing state is referred to as the cutting position.

[0086] (Structure of the stranding mechanism 30)

[0087] As Figure 7As shown, the stranding mechanism 30 includes a stranding motor 76, a reduction unit 78, and a holding unit 82. The stranding motor 76 is connected to the control substrate 20 by wiring (not shown). The stranding motor 76 is driven by the power supplied from the battery B. The stranding motor 76 is controlled by the control substrate 20. The stranding motor 76 is connected to the screw shaft 84 of the holding unit 82 via the reduction unit 78. The reduction unit 78, for example, uses a planetary gear mechanism to reduce the rotation of the stranding motor 76 and transmit it to the screw shaft 84.

[0088] In this embodiment, the stranding motor 76 is a brushless motor. In this embodiment, the stranding motor 76 has the same structure as the feeding motor 32. As Figure 18 shown, the stranding motor 76 includes a stator 186 having a tooth portion 184 around which a coil 182 is wound, a rotor 188 disposed inside the stator 186, and a sensor substrate 190 fixed to the stator 186. The stator 186 is made of a magnetic material. The rotor 188 has permanent magnets with magnetic poles arranged in the circumferential direction. As Figure 19 shown, a Hall sensor 192 is provided on the sensor substrate 190. The Hall sensor 192 includes a first Hall element 192a, a second Hall element 192b, and a third Hall element 192c. The first Hall element 192a, the second Hall element 192b, and the third Hall element 192c detect the magnetic force from the rotor 188. The Hall sensor 192 is arranged on the sensor substrate 190 at a position where the electrical angle is 25° ahead with respect to the forward rotation of the stranding motor 76 and 25° behind with respect to the reverse rotation of the stranding motor 76. In addition, in this embodiment, the control substrate 20 outputs patterns staggered by one stage at every 60° electrical angle with respect to the reverse rotation of the stranding motor 76. Therefore, control is performed with a 25° leading angle with respect to the forward rotation of the stranding motor 76 and a 60° - 25° = 35° leading angle with respect to the reverse rotation of the stranding motor 76.

[0089] In this embodiment, the stranding motor 76 and the feeding motor 32 have the same structure. Therefore, the stator 174 and the stator 186 use common components, the rotor 176 and the rotor 188 use common components, and the sensor substrate 178 and the sensor substrate 190 use common components.

[0090] As Figure 7 shown, the holding unit 82 includes a screw shaft 84, a clamp guide 86 (refer to Figure 8 , Figure 9 ), a biasing member 92 (refer to Figure 8 , Figure 9 ), a sleeve 88, and a clamping member 90.

[0091] The screw shaft 84 is connected to the reduction unit 78. When the twisting motor 76 rotates forward, the screw shaft 84 rotates in the left-handed thread direction when viewed from the rear. When the twisting motor 76 rotates in the reverse direction, the screw shaft 84 rotates in the right-handed thread direction when viewed from the rear.

[0092] As Figure 8 shown, the screw shaft 84 includes a thick-diameter portion 84a and a thin-diameter portion 84b. The thick-diameter portion 84a is located at the rear of the screw shaft 84, and the thin-diameter portion 84b is located at the front of the screw shaft 84. A spiral ball groove 84c is formed on the outer peripheral surface of the thick-diameter portion 84a. The ball 94 is fitted into the ball groove 84c. A ring-shaped washer 96 is disposed on the step between the thick-diameter portion 84a and the thin-diameter portion 84b. An engagement groove 84d is formed at the front of the thin-diameter portion 84b.

[0093] As Figure 9 shown, the front portion of the thin-diameter portion 84b enters the recess 86a of the jig guide 86. The engagement pin 86b of the jig guide 86 enters the engagement groove 84d of the thin-diameter portion 84b of the screw shaft 84 and can engage with the front side surface and the rear side surface of the engagement groove 84d. A step portion 86c is formed on the outer peripheral surface of the jig guide 86. The diameter of the outer peripheral surface of the jig guide 86 at a position rearward of the step portion 86c is larger than the diameter of the outer peripheral surface of the jig guide 86 at a position forward of the step portion 86c.

[0094] In addition, the thin-diameter portion 84b passes through the biasing member 92. The biasing member 92 is disposed between the washer 96 and the jig guide 86. The biasing member 92 biases the jig guide 86 in a direction separating from the washer 96.

[0095] The screw shaft 84 and the jig guide 86 are inserted into the sleeve 88. The sleeve 88 includes an inner sleeve 100 and an outer sleeve 102. The thick-diameter portion 84a of the screw shaft 84 passes through the inner sleeve 100. A ball hole (not shown) is formed in the inner sleeve 100. The ball 94 is fitted into the ball hole. The inner sleeve 100 is connected to the screw shaft 84 by means of the ball 94 fitted between the ball groove 84c and the ball hole, that is, by means of a ball screw. Within the range where the ball groove 84c is formed, when the screw shaft 84 rotates relative to the inner sleeve 100, the inner sleeve 100 moves in the front-rear direction relative to the screw shaft 84.

[0096] The screw shaft 84, the clamp guide 86, and the inner sleeve 100 are inserted into the outer sleeve 102. The outer sleeve 102 has a cylindrical shape extending in the front-rear direction. A stepped portion 102a is formed on the inner peripheral surface of the outer sleeve 102. The diameter of the inner peripheral surface of the outer sleeve 102 at a position forward of the stepped portion 102a is smaller than the diameter of the inner peripheral surface of the outer sleeve 102 at a position rearward of the stepped portion 102a. The outer sleeve 102 is fixed to the inner sleeve 100 by fixing screws 106. The outer sleeve 102 moves (i.e., moves or rotates) together with the inner sleeve 100. In the range where the ball groove 84c is formed, when the screw shaft 84 rotates relative to the inner sleeve 100, the outer sleeve 102 and the inner sleeve 100 move together in the front-rear direction relative to the screw shaft 84. Further, when the screw shaft 84 rotates relative to the inner sleeve 100, the outer sleeve 102 moves between the forward position and the backward position relative to the clamp guide 86. Hereinafter, the movement of the outer sleeve 102 toward the forward position (i.e., forward) relative to the clamp guide 86 is referred to as the forward movement of the outer sleeve 102, and the movement of the outer sleeve 102 toward the backward position (i.e., backward) relative to the clamp guide 86 is referred to as the backward movement of the outer sleeve 102.

[0097] The holding portion 82 further includes a support member 104. The support member 104 covers the outer peripheral surface of the outer sleeve 102. The support member 104 can rotate relative to the outer sleeve 102. The support member 104 can move in the front-rear direction relative to the outer sleeve 102. The outer sleeve 102 can be supported on the main body 4 by means of the support member 104.

[0098] The clamping member 90 is supported at the front portion of the clamp guide 86. The clamping member 90 is supported on the outer sleeve 102 by two guide pins 110 (see Figure 8 ) so as to be movable relative to the outer sleeve 102. The clamping member 90 is a member for clamping the wire W. The clamping member 90 opens and closes in conjunction with the rotation of the screw shaft 84.

[0099] The clamping member 90 includes an upper clamping member 114 and a lower clamping member 116. The upper clamping member 114 and the lower clamping member 116 face each other in the up-down direction. As Figure 10 shown, the upper clamping member 114 includes an upper base portion 118, a first upper protrusion 120, an upper connecting portion 121, and a second upper protrusion 122. The upper base portion 118 is a portion supported on the clamp guide 86 and the guide pin 110. The upper base portion 118 has two upper guide holes 118a. The two upper guide holes 118a have the same shape as each other. The two upper guide holes 118a extend in the front-rear direction, and when the upper base portion 118 is viewed from above, the upper guide holes 118a are inclined to the right from the rear toward the front.

[0100] The first upper protrusion 120 extends forward from the left front end of the upper base 118. The upper connecting portion 121 extends rightward from the central right end of the first upper protrusion 120. The second upper protrusion 122 extends forward from the upper connecting portion 121. The first upper protrusion 120 and the second upper protrusion 122 are separated in the left-right direction. A first wire passage 124 is formed between the first upper protrusion 120 and the second upper protrusion 122. The wire W after being sent out from the feeding mechanism 24 and before reaching the upper guiding passage 58a of the guiding mechanism 26 passes through the first wire passage 124.

[0101] The clamping member 90 further includes Figure 12 the first anti-disengagement portion 123 as shown. The first anti-disengagement portion 123 is integrally formed with the upper clamping member 114. The first anti-disengagement portion 123 extends downward from the front end of the second upper protrusion 122. The first anti-disengagement portion 123 partially overlaps with the lower clamping member 116 in the front-rear direction. The first anti-disengagement portion 123 inhibits the wire W clamped by the clamping member 90 from disengaging from the clamping member 90.

[0102] As Figure 11 shown, the lower clamping member 116 includes a lower base 126, a first lower protrusion 128, a lower connecting portion 129, and a second lower protrusion 130. The lower base 126 is the portion supported by the jig guide 86 and the guide pin 110. The lower base 126 has two lower guide holes 126a. The shape of the lower guide holes 126a when observing the lower base 126 from above is in a facing symmetry relationship with respect to the plane orthogonal to the left-right direction as compared with the shape of the upper guide holes 118a when observing the upper base 118 from above. That is, the two lower guide holes 126a extend in the front-rear direction, and when observing the lower base 126 from above, the lower guide holes 126a are inclined leftward from the rear to the front.

[0103] The first lower protrusion 128 extends forward from the right front end of the lower base 126. The lower connecting portion 129 extends leftward from the central left end of the first lower protrusion 128. The second lower protrusion 130 extends forward from the central front end of the lower connecting portion 129. The first lower protrusion 128 and the second lower protrusion 130 are separated in the left-right direction. A second wire passage 132 is formed between the first lower protrusion 128 and the second lower protrusion 130. The wire W after passing through the lower guiding passage 60a of the guiding mechanism 26 passes through the second wire passage 132.

[0104] The clamping member 90 further includes a second anti - detachment portion 131. The second anti - detachment portion 131 is integrally formed with the lower clamping member 116. The second anti - detachment portion 131 extends leftward from the left front end of the second lower protrusion 130. The second anti - detachment portion 131 inhibits the wire W clamped by the clamping member 90 from detaching from the clamping member 90. The second anti - detachment portion 131 and the lower connecting portion 129 are separated in the front - rear direction. An auxiliary passage 134 is formed between the second anti - detachment portion 131 and the lower connecting portion 129.

[0105] As Figure 8 shown, in a state where the upper clamping member 114 and the lower clamping member 116 overlap in the up - down direction, the guide pins 110 of the outer sleeve 102 penetrate through the upper guide hole 118a and the lower guide hole 126a respectively. If the outer sleeve 102 moves in the front - rear direction relative to the jig guide 86, the guide pins 110 move in the front - rear direction within the upper guide hole 118a and the lower guide hole 126a. When the guide pins 110 are disposed at the front portions of the upper guide hole 118a and the lower guide hole 126a, as Figure 12 shown, the first wire passage 124 and the second wire passage 132 are open. The state of the clamping member 90 at this time is referred to as the fully - open state.

[0106] If the outer sleeve 102 retreats relative to the jig guide 86, the guide pins 110 move rearward within the upper guide hole 118a and the lower guide hole 126a. If the upper clamping member 114 moves rightward relative to the jig guide 86, the lower clamping member 116 moves leftward (i.e., in a direction opposite to the direction in which the upper clamping member 114 moves) relative to the jig guide 86. The distance that the upper clamping member 114 moves rightward is the same as the distance that the lower clamping member 116 moves leftward. When observing the clamping member 90 in the up - down direction, the upper clamping member 114 and the lower clamping member 116 move in a direction approaching each other. As Figure 13 shown, when the guide pins 110 move to the middle positions within the upper guide hole 118a and the lower guide hole 126a, the second wire passage 132 is closed by the second upper protrusion 122. On the other hand, the first wire passage 124 is open by using the auxiliary passage 134 formed in the second lower protrusion 130. The state of the clamping member 90 at this time is referred to as the semi - open state. When the wire W is disposed in the second wire passage 132, the wire W is clamped and fixed by the first clamping portion P1 between the second upper protrusion 122 and the first lower protrusion 128. Hereinafter, the portion of the wire W clamped by the first clamping portion P1 is referred to as the first clamped portion WP1. In the semi - open state, the first anti - detachment portion 123 closes the first clamping portion P1 from the front. In addition, in Figure 13 Figure, the position of the first anti - detachment portion 123 in the front - rear direction is illustrated by a dotted line. The first anti - detachment portion 123 is disposed on the steel bar R (Figure 13 between the omitted illustration) and the first clamping portion P1.

[0107] As Figure 14 shown, when the guide pin 110 moves to the rear of the upper guide hole 118a and the lower guide hole 126a, the first wire passage 124 is closed by the second lower protrusion 130. The second wire passage 132 remains in a state of being closed by the second upper protrusion 122. The state of the clamping member 90 at this time is referred to as the fully closed state. When a wire W is disposed in the first wire passage 124, while the first clamped portion WP1 of the wire W remains held by the first clamping portion P1 of the clamping member 90, the wire W is clamped and fixed by the second clamping portion P2 between the first upper protrusion 120 and the second lower protrusion 130. Hereinafter, the portion of the wire W clamped by the second clamping portion P2 is referred to as the second clamped portion WP2. In the fully closed state, the first anti - detachment portion 123 closes the first clamping portion P1 from the front, and the second anti - detachment portion 131 is disposed directly below and in front of the second clamping portion P2. In addition, in Figure 14 , the front end portion of the second anti - detachment portion 131 is illustrated by a dotted line with a pitch shorter than the pitch of the dotted line representing the first anti - detachment portion 123. The second anti - detachment portion 131 is disposed between the reinforcing bar R ( Figure 14 omitted illustration) and the second clamping portion P2.

[0108] As Figure 7 shown, the holding portion 82 further includes a push plate 140. The push plate 140 is clamped between the rib 100a formed at the rear end portion of the inner sleeve 100 and the rear end portion of the outer sleeve 102. The push plate 140 moves in the front - rear direction relative to the screw shaft 84 together with the inner sleeve 100 and the outer sleeve 102 by the rotation of the screw shaft 84 accompanying the drive of the stranding motor 76.

[0109] As Figure 5 and Figure 6 shown, the push plate 140 operates the operated member 72 of the cutting mechanism 28. As Figure 5 shown, in the normal state, the push plate 140 is separated from the tab 72b of the operated member 72. At this time, the operated member 72 is located at the initial position. If the push plate 140 retreats relative to the screw shaft 84 by the rotation of the screw shaft 84, the push plate 140 abuts against the tab 72b and pushes the operated member 72 rearward. Thereby, the operated member 72 rotates about the rotation shaft 72a, the connecting member 70 moves forward, and the cutting member 66 rotates about the rotation shaft 66a. The push plate 140 can operate the cutting member 66 by operating the operated member 72. As Figure 6As shown, when the operated member 72 rotates to the cutting position, the wire W passing through the inside of the cutting member 66 is cut by the cutting member 66. After that, when the push plate 140 advances relative to the screw shaft 84 by the rotation of the screw shaft 84, the operated member 72 is urged by the urging member 74 and rotates about the rotation shaft 72a to the initial position. Thus, the connecting member 70 and the cutting member 66 also return to Figure 5 the state shown.

[0110] An initial state detection magnet 140a and a gripping detection magnet 140b are provided on the push plate 140. As Figure 7 shown, the stranding mechanism 30 includes an initial state detection sensor 136 that detects the magnetic force from the initial state detection magnet 140a and a gripping detection sensor 138 that detects the magnetic force from the gripping detection magnet 140b. The positions of the initial state detection sensor 136 and the gripping detection sensor 138 are fixed relative to the main body 4. When the stranding mechanism 30 is in the initial state, the initial state detection sensor 136 is disposed opposite to the initial state detection magnet 140a. Therefore, the initial state detection sensor 136 can detect whether the stranding mechanism 30 is in the initial state. In the stranding mechanism 30, when the clamping member 90 is in the semi-open state, that is, when the clamping member 90 holds the front end of the wire W, the gripping detection sensor 138 is disposed opposite to the gripping detection magnet 140b. Therefore, the gripping detection sensor 138 can detect whether the clamping member 90 is in the state of holding the front end of the wire W in the stranding mechanism 30.

[0111] As Figure 7 shown, fins 144 are formed on the outer peripheral surface of the rear portion of the outer sleeve 102. The fins 144 extend in the front-rear direction. The fins 144 allow or prohibit the rotation of the outer sleeve 102. In the present embodiment, on the outer peripheral surface of the outer sleeve 102, eight fins are arranged at intervals of 45 degrees from each other. Further, in the present embodiment, the fins 144 include seven short fins 146 and one long fin 148. The length of the long fin 148 in the front-rear direction is longer than the length of the short fin 146 in the front-rear direction. In the front-rear direction, the position of the front end portion of the long fin 148 is the same as the position of the front end portion of the short fin 146. On the other hand, in the front-rear direction, the rear end portion of the long fin 148 is located behind the rear end portion of the short fin 146.

[0112] The steel bar bundling machine 2 further includes Figure 15 the rotation restricting portion 150 shown. As Figure 17 shown, the rotation restricting portion 150 is disposed at a position close to the outer sleeve 102. The rotation restricting portion 150 allows or prohibits the rotation of the outer sleeve 102 in cooperation with the fins 144. As Figure 15As shown, the rotation restricting portion 150 includes a base member 152, an upper stopper 154, a lower stopper 156, swing shafts 158, 160, and biasing members 162, 164. The base member 152 is fixed relative to the main body 4. The upper stopper 154 is swingably supported by the base member 152 via the swing shaft 158. The upper stopper 154 has a restricting piece 154a. The restricting piece 154a is located at the lower part of the upper stopper 154. The biasing member 162 biases the restricting piece 154a in a direction to open outward (i.e., a direction in which the restricting piece 154a separates from the base member 152).

[0113] When the screw shaft 84 rotates in the right-handed thread direction when viewed from the rear, the short fins 146 and the long fins 148 are pushed into the restricting piece 154a. Therefore, the upper stopper 154 does not prohibit the rotation of the outer sleeve 102. On the other hand, when the screw shaft 84 rotates in the left-handed thread direction when viewed from the rear, the short fins 146 and the long fins 148 abut against the restricting piece 154a in the rotation direction of the outer sleeve 102. Therefore, the upper stopper 154 prohibits the rotation of the outer sleeve 102. The case where the screw shaft 84 rotates in the right-handed thread direction when viewed from the rear corresponds to the case where the stranding mechanism 30 finishes stranding the wire W around the reinforcing bar R and returns to the initial state. In addition, the case where the screw shaft 84 rotates in the left-handed thread direction when viewed from the rear corresponds to the case where the stranding mechanism 30 clamps the wire W around the reinforcing bar R and strands it.

[0114] The lower stopper 156 is swingably supported by the base member 152 via the swing shaft 160. The lower stopper 156 has a restricting piece 156a. The restricting piece 156a is located at the upper part of the lower stopper 156. The restricting piece 156a faces the restricting piece 154a. The rear end portion of the restricting piece 156a is disposed at a position rearward of the rear end portion of the restricting piece 154a. The front end portion of the restricting piece 156a is disposed at a position rearward of the front end portion of the restricting piece 154a. The biasing member 164 biases the restricting piece 156a in a direction to open outward (i.e., a direction in which the restricting piece 156a separates from the base member 152).

[0115] When the screw shaft 84 rotates in the right-handed thread direction when viewed from the rear, the short fins 146 and the long fins 148 abut against the restricting piece 156a in the rotation direction of the outer sleeve 102. Therefore, the lower stopper 156 prohibits the rotation of the outer sleeve 102. On the other hand, when the screw shaft 84 rotates in the left-handed thread direction when viewed from the rear, the short fins 146 and the long fins 148 are pushed into the restricting piece 156a. Therefore, the lower stopper 156 does not prohibit the rotation of the outer sleeve 102.

[0116] In addition, regarding the mechanical structure of the wire tying machine 2, various modifications can also be made to the above structure. For example, in the wire tying machine 2, the reel holder 12 can be arranged at the rear of the main body 4, or the feeding mechanism 24 can be arranged between the reel holder 12 and the guiding mechanism 26 of the main body 4. In this case, the reel 18, the feeding motor 32, and the twisting motor 76 are all arranged at positions above the handle 6. Alternatively, the control board 20 and the display board 22 can be housed inside the main body 4. In this case, the control board 20 and the display board 22 are arranged at positions above the handle 6.

[0117] (Operation of the wire tying machine 2)

[0118] Next, refer to Figure 4 , Figure 9 , Figure 16 , Figure 17 to describe the operation of the wire tying machine 2 for tying the steel bar R with the steel wire W. When the wire tying machine 2 ties the steel bar R with the steel wire W, the feeding process, the front end holding process, the pulling-back process, the rear end holding process, the cutting process, the pulling process, and the twisting process are sequentially executed. Here, in the initial state before the wire tying machine 2 executes the operation of tying the steel bar R with the steel wire W, as Figure 9 shown, only the front part of the screw shaft 84 is arranged inside the inner sleeve 100. In addition, the long fin 148 is clamped between the restricting member 154a of the upper stopper 154 and the restricting member 156a of the lower stopper 156. In addition, the outer sleeve 102 is in the advanced position relative to the clamp guide 86. The two guide pins 110 are located in front of the two upper guide holes 118a and the two lower guide holes 126a, and the clamping member 90 is in the fully open state. As Figure 5 shown, the push plate 140 is separated from the tab 72b of the operated member 72, and the operated member 72 is in the initial position.

[0119] (Feeding process)

[0120] If the feeding motor 32 rotates in the reverse direction from the initial state, the feeding mechanism 24 feeds out a predetermined length of the steel wire W wound around the reel 18. The front end portion of the steel wire W sequentially passes through the inside of the cutting member 66, the first wire passage 124, the upper guide passage 58a, the lower guide passage 60a, and the second wire passage 132. Thus, as Figure 4 shown, the steel wire W is wound around the steel bar R in a circular shape.

[0121] (Front end holding process)

[0122] If the stranding motor 76 rotates forward from this state, the screw shaft 84 rotates in the left-handed thread direction. The long fin 148 abuts against the restricting member 154a of the upper stopper 154 in the rotation direction of the outer sleeve 102, thereby prohibiting the rotation of the outer sleeve 102 in the left-handed thread direction. Accordingly, the outer sleeve 102 and the inner sleeve 100 together retreat relative to the jig guide 86. Along with the retreat of the outer sleeve 102, the two guide pins 110 move from the front to the middle positions within the two upper guide holes 118a and the two lower guide holes 126a. The clamping member 90 changes from the fully open state to the semi-open state, and the vicinity of the front end of the wire W (i.e., the first clamped portion WP1) is clamped and fixed by the first clamping portion P1 between the second upper protrusion 122 and the first lower protrusion 128. Thereby, the vicinity of the front end of the wire W is held by the clamping member 90. In this state, the first anti-disengagement portion 123 closes the first clamping portion P1 of the clamping member 90 from the front.

[0123] (Pull-back process)

[0124] If the stranding motor 76 stops from this state and the feeding motor 32 rotates forward, the feeding unit 36 pulls back the wire W around the steel bar R. The vicinity of the front end portion of the wire W is held by the clamping member 90, and the wire W around the steel bar R is reduced in diameter.

[0125] (Rear-end holding process)

[0126] If the stranding motor 76 rotates forward again from this state, the outer sleeve 102 and the inner sleeve 100 together retreat further relative to the jig guide 86. Along with the retreat of the outer sleeve 102, the two guide pins 110 move from the middle positions to the rear within the two upper guide holes 118a and the two lower guide holes 126a. The clamping member 90 changes from the semi-open state to the fully closed state, and the vicinity of the rear end of the wire W (i.e., the second clamped portion WP2) is clamped and fixed by the second clamping portion P2 between the first upper protrusion 120 and the second lower protrusion 130. Thereby, the vicinity of the rear end of the wire W is held by the clamping member 90. In this state, the first anti-disengagement portion 123 closes the first clamping portion P1 of the clamping member 90 from the front, and the second anti-disengagement portion 131 is disposed directly below the second clamping portion P2 of the clamping member 90. In addition, the first anti-disengagement portion 123 and the second anti-disengagement portion 131 are disposed between the steel bar R and the wire W.

[0127] (Cutting process)

[0128] From this state, along with the forward rotation of the stranding motor 76, the outer sleeve 102 retreats further relative to the jig guide 86. As Figure 6As shown, the push plate 140 retracts together with the outer sleeve 102, abuts against the tab 72b of the operated member 72, and is pushed backward. If the operated member 72 rotates about the rotation shaft 72a to the cutting position, the cutting member 66 rotates about the rotation shaft 66a to the predetermined position. Thereby, the steel wire W inside the cutting member 66 is cut. The steel wire W around the reinforcing bar R is held by the holding member 90 at two locations near the front end portion and the rear end portion of the steel wire W.

[0129] (Pulling process)

[0130] If, from this state, with the forward rotation of the stranding motor 76, the outer sleeve 102 further retracts relative to the jig guide 86, then as Figure 16 shown, the stepped portion 102a of the outer sleeve 102 abuts against the stepped portion 86c of the jig guide 86. Therefore, the outer sleeve 102 cannot further retract relative to the jig guide 86 and retracts integrally with the jig guide 86. Thereby, the holding member 90 retracts, that is, the holding member 90 moves in the direction of separating from the reinforcing bar R, and the steel wire W around the reinforcing bar R is pulled in the direction of separating from the reinforcing bar R. During the execution of the pulling process, the first anti-disengagement portion 123 closes the front of the first holding portion P1, and the second anti-disengagement portion 131 is disposed directly below and in front of the second holding portion P2. Therefore, when the steel wire W moves forward relative to the holding member 90 by the tension applied to the steel wire W by pulling the steel wire W, the near-front portion WP1 of the front end of the steel wire W abuts against the first anti-disengagement portion 123, and the near-rear portion WP2 of the rear end of the steel wire W abuts against the second anti-disengagement portion 131. Thereby, the steel wire W is pulled in the direction of separating from the reinforcing bar R on the premise that it will not detach from the holding member 90.

[0131] (Stranding process)

[0132] If, from this state, with the forward rotation of the stranding motor 76, the outer sleeve 102 retracts together with the jig guide 86, then as Figure 17As shown, the long fin 148 does not abut against the restricting member 154a of the upper stopper 154 in the rotation direction of the outer sleeve 102. Thereby, rotation of the outer sleeve 102 in the left-handed thread direction is permitted. In this state, the biasing member 92 is compressed, and a biasing force is applied from the biasing member 92 to the jig guide 86 in a direction to separate the jig guide 86 from the washer 96. Accordingly, a frictional force acts between the ball 94 fitted in the ball hole of the inner sleeve 100 and the ball groove 84c of the screw shaft 84. As a result, when the jig guide 86 rotates, the outer sleeve 102 does not retreat relative to the screw shaft 84, but rather the outer sleeve 102 rotates integrally with the screw shaft 84 in the left-handed thread direction. Thereby, the jig guide 86 and the clamping member 90 rotate in the left-handed thread direction, and the wire W held by the clamping member 90 is twisted. During the execution of the twisting process, similar to the case of executing the pulling process, the first anti-disengagement portion 123 closes the front of the first clamping portion P1, and the second anti-disengagement portion 131 is disposed directly below and in front of the second clamping portion P2. Accordingly, in the case where the wire W is moved forward relative to the clamping member 90 by the tension applied to the wire W accompanying the twisting of the wire W, the vicinity portion WP1 of the front end of the wire W abuts against the first anti-disengagement portion 123, and the vicinity portion WP2 of the rear end of the wire W abuts against the second anti-disengagement portion 131. Thereby, the wire W is twisted without detaching from the clamping member 90.

[0133] (Initial state restoration process)

[0134] Then, the twisting motor 76 rotates in the reverse direction, and the screw shaft 84 rotates in the right-handed thread direction. The outer sleeve 102 rotates in the right-handed thread direction, and the short fin 146 or the long fin 148 abuts against the restricting member 156a of the lower stopper 156, thereby prohibiting rotation of the outer sleeve 102 in the right-handed thread direction. A biasing force is applied from the biasing member 92 to the jig guide 86 in a direction to separate the jig guide 86 from the washer 96, and the outer sleeve 102 advances integrally with the jig guide 86. When the engagement pin 86b abuts against the front end portion of the engagement groove 84d, the outer sleeve 102 advances relative to the jig guide 86. When the two guide pins 110 move from the rear to the front in the two upper guide holes 118a and the two lower guide holes 126a, the clamping member 90 becomes fully open. Thereby, the wire W held by the clamping member 90 detaches from the clamping member 90. In the case where the short fin 146 abuts against the restricting member 156a, the outer sleeve 102 advances relative to the jig guide 86, and when the short fin 146 moves to a position in front of the front end portion of the restricting member 156a, the outer sleeve 102 rotates again in the right-handed thread direction. When the long fin 148 abuts against the restricting member 156a, rotation of the outer sleeve 102 is prohibited. Thereby, the twisting mechanism 30 is restored to the initial state.

[0135] (Circuit Structure of Control Substrate 20)

[0136] As shown in Figure 20 , on the control substrate 20, there are provided a control power supply circuit 200, an MCU (Micro Control Unit) 202, a motor control signal output destination switching circuit 204, a motor rotation signal input source switching circuit 206, gate drive circuits 208, 210, inverter circuits 212, 214, a current detection circuit 216, braking circuits 218, 220, etc.

[0137] The control power supply circuit 200 adjusts the power supplied from the battery B to a predetermined voltage and supplies power to the MCU 202, the braking circuits 218, 220, etc.

[0138] As shown in Figure 21 , the inverter circuit 212 includes switching elements 222a, 222b, 224a, 224b, 226a, 226b. The switching elements 222a, 222b, 224a, 224b, 226a, 226b are field effect transistors, specifically MOSFETs with insulated gates. The switching element 222a connects the positive electrode side potential line 228 and the motor power line 232. The switching element 222b connects the negative electrode side potential line 230 and the motor power line 232. The switching element 224a connects the positive electrode side potential line 228 and the motor power line 234. The switching element 224b connects the negative electrode side potential line 230 and the motor power line 234. The switching element 226a connects the positive electrode side potential line 228 and the motor power line 236. The switching element 226b connects the negative electrode side potential line 230 and the motor power line 236. The positive electrode side potential line 228 is connected to the positive electrode side power potential of the battery B. The negative electrode side potential line 230 is connected to the current detection circuit 216. The motor power lines 232, 234, 236 are connected to the coil 170 of the feed motor 32 (refer to Figure 18 , Figure 19 ).

[0139] Similarly, the inverting circuit 214 includes switching elements 238a, 238b, 240a, 240b, 242a, and 242b. The switching elements 238a, 238b, 240a, 240b, 242a, and 242b are field effect transistors, specifically MOSFETs with insulated gates. The switching element 238a connects the positive-side potential line 244 and the motor power line 248. The switching element 238b connects the negative-side potential line 246 and the motor power line 248. The switching element 240a connects the positive-side potential line 244 and the motor power line 250. The switching element 240b connects the negative-side potential line 246 and the motor power line 250. The switching element 242a connects the positive-side potential line 244 and the motor power line 252. The switching element 242b connects the negative-side potential line 246 and the motor power line 252. The positive-side potential line 244 is connected to the positive-side power potential of the battery B. The negative-side potential line 246 is connected to the current detection circuit 216. The motor power lines 248, 250, and 252 are connected to the coil 182 of the stranded motor 76 (refer to Figure 18 , Figure 19 ).

[0140] The gate drive circuit 208 controls the operation of the feed motor 32 by switching each of the switching elements 222a, 224a, 226a, 222b, 224b, and 226b of the inverting circuit 212 between conduction and non-conduction in accordance with the motor control signals UH1, VH1, WH1, UL1, VL1, and WL1. Additionally, when the feed motor 32 is rotating, if the gate drive circuit 208 sets all of the switching elements 222a, 224a, 226a, 222b, 224b, and 226b to non-conduction, the power supply to the feed motor 32 is blocked, and the feed motor 32 stops after continuing to rotate by inertia. Furthermore, when the feed motor 32 is rotating, if the gate drive circuit 208 sets the switching elements 222a, 224a, 226a to non-conduction and the switching elements 222b, 224b, 226b to conduction, a so-called short-circuit braking is applied to the feed motor 32, and the rotation of the feed motor 32 immediately stops. Additionally, hereinafter, the motor control signals UH1, VH1, WH1, UL1, VL1, and WL1 in which UL1, VL1, and WL1 are all at the H potential (in this case, all of the switching elements 222b, 224b, and 226b become conductive) are also referred to as short-circuit braking signals.

[0141] Similarly, the gate drive circuit 210 controls the operation of the stranding motor 76 by switching each of the switching elements 238a, 240a, 242a, 238b, 240b, 242b of the inverter circuit 214 between conduction and non-conduction in correspondence with the motor control signals UH2, VH2, WH2, UL2, VL2, WL2. Further, when the stranding motor 76 is rotating, if the gate drive circuit 210 sets all of the switching elements 238a, 240a, 242a, 238b, 240b, 242b to non-conduction, the power supply to the stranding motor 76 is blocked, and the stranding motor 76 stops after continuing to rotate by inertia. Further, when the stranding motor 76 is rotating, if the gate drive circuit 210 sets the switching elements 238a, 240a, 242a to non-conduction and sets the switching elements 238b, 240b, 242b to conduction, a so-called short-circuit braking is applied to the stranding motor 76, and the rotation of the stranding motor 76 immediately stops. Further, hereinafter, the motor control signals UH2, VH2, WH2, UL2, VL2, WL2 in which UL2, VL2, WL2 are all at the H potential (in this case, all of the switching elements 238b, 240b, 242b become conductive) are also referred to as short-circuit braking signals.

[0142] As Figure 20 shown, the current detection circuit 216 is disposed between the inverter circuit 212 and the inverter circuit 214 and the negative-side power supply potential of the battery B. The current detection circuit 216 detects the magnitude of the current flowing in the inverter circuit 212 and the inverter circuit 214. The current detection circuit 216 outputs the detected current value to the MCU 202.

[0143] The MCU 202 includes a motor control signal output port 202a, a motor rotation signal input port 202b, and a general-purpose input / output port 202c. The motor control signal output port 202a is provided to output the motor control signals UH, VH, WH, UL, VL, WL to the brushless motor, and can perform higher-speed signal processing compared to the general-purpose input / output port 202c. The motor rotation signal input port 202b is provided to input the Hall sensor signals Hu, Hv, Hw from the brushless motor, and can perform higher-speed signal processing compared to the general-purpose input / output port 202c. The setting display LED 22a and the setting switch 22b, the trigger switch 9, the initial state detection sensor 136, the grip detection sensor 138, and the current detection circuit 216 on the display substrate 22 are connected to the general-purpose input / output port 202c of the MCU 202.

[0144] The motor control signal output port 202a of the MCU 202 is connected to the motor control signal output destination switching circuit 204. The motor control signal output destination switching circuit 204 switches the output destinations of the motor control signals UH, VH, WH, UL, VL, and WL output from the motor control signal output port 202a between the gate drive circuit 208 and the gate drive circuit 210 in accordance with the switching signal SW output from the general-purpose input / output port 202c of the MCU 202.

[0145] As Figure 22 shown, the motor control signal output destination switching circuit 204 may also be configured to include a demultiplexer 260. When the switching signal SW output from the MCU 202 is at the H potential, the demultiplexer 260 outputs the motor control signal UH output from the MCU 202 as the motor control signal UH1 to the gate drive circuit 208. When the switching signal SW output from the MCU 202 is at the L potential, the demultiplexer 260 outputs the motor control signal UH output from the MCU 202 as the motor control signal UH2 to the gate drive circuit 210. In addition, for the sake of easy understanding, only the structure corresponding to the motor control signal UH is described here, but the motor control signal output destination switching circuit 204 has the same structure for the other motor control signals VH, WH, UL, VL, and WL.

[0146] Alternatively, it may also be as Figure 23 shown, the motor control signal output destination switching circuit 204 is configured to include FETs 262, 264, and a NOT gate 266. When the switching signal SW output from the MCU 202 is at the H potential, the FET 262 is turned on and the FET 264 is turned off. In this case, the motor control signal output destination switching circuit 204 outputs the motor control signal UH output from the MCU 202 as the motor control signal UH1 to the gate drive circuit 208. When the switching signal SW output from the MCU 202 is at the L potential, the FET 262 is turned off and the FET 264 is turned on. In this case, the motor control signal output destination switching circuit 204 outputs the motor control signal UH output from the MCU 202 as the motor control signal UH2 to the gate drive circuit 210. In addition, for the sake of easy understanding, only the structure corresponding to the motor control signal UH is described here, but the motor control signal output destination switching circuit 204 has the same structure for the other motor control signals VH, WH, UL, VL, and WL.

[0147] Alternatively, it may also be as Figure 24As shown, the motor control signal output destination switching circuit 204 is configured to include NOR gates 268, 270 and NOT gates 272, 274. When the switching signal SW output from the MCU 202 is at the H potential, the NOR gate 268 outputs the motor control signal UH output from the MCU 202, and the NOR gate 270 outputs the L potential. In this case, the motor control signal output destination switching circuit 204 outputs the motor control signal UH output from the MCU 202 as the motor control signal UH1 to the gate drive circuit 208. When the switching signal SW output from the MCU 202 is at the L potential, the NOR gate 268 outputs the L potential, and the NOR gate 270 outputs the motor control signal UH output from the MCU 202. In this case, the motor control signal output destination switching circuit 204 outputs the motor control signal UH output from the MCU 202 as the motor control signal UH2 to the gate drive circuit 210. In addition, for the sake of easy understanding, only the structure corresponding to the motor control signal UH is described here, but the motor control signal output destination switching circuit 204 has the same structure for other motor control signals VH, WH, UL, VL, WL.

[0148] As Figure 25 shown, the braking circuit 218 is connected to the signal lines of the motor control signals UL1, VL1, WL1 output from the motor control signal output destination switching circuit 204 to the gate drive circuit 208. The braking circuit 218 applies a short-circuit brake to the feed motor 32 in response to the brake signal BR1 output from the general-purpose input / output port 202c of the MCU 202. The braking circuit 218 includes transistors 274a, 274b, 274c, 274d and resistors 276a, 276b, 276c, 276d, 276e, 276f, 276g, 276h. When the brake signal BR1 input from the MCU 202 is at the L potential, since the transistor 274a is turned off and the transistors 274b, 274c, 274d are all turned off, the motor control signals UL1, VL1, WL1 output from the motor control signal output destination switching circuit 204 are directly input to the gate drive circuit 208. When the brake signal BR1 input from the MCU 202 is at the H potential, since the transistor 274a is turned on and the transistors 274b, 274c, 274d are all turned on, all the motor control signals UL1, VL1, WL1 input to the gate drive circuit 208 become the H potential. In this case, a short-circuit brake signal is input to the gate drive circuit 208 to apply a short-circuit brake to the feed motor 32.

[0149] Similarly, the braking circuit 220 is connected to the signal lines of the motor control signals UL2, VL2, and WL2 output from the motor control signal output destination switching circuit 204 to the gate drive circuit 210. The braking circuit 220 applies a short-circuit brake to the stranded motor 76 in response to the braking signal BR2 output from the general-purpose input / output port 202c of the MCU 202. The braking circuit 220 has the same structure as the braking circuit 218. The braking circuit 220 includes transistors 278a, 278b, 278c, 278d and resistors 280a, 280b, 280c, 280d, 280e, 280f, 280g, 280h. When the braking signal BR2 input from the MCU 202 is at the L potential, since the transistor 278a is turned off and the transistors 278b, 278c, 278d are all turned off, the motor control signals UL2, VL2, and WL2 output from the motor control signal output destination switching circuit 204 are directly input to the gate drive circuit 210. When the braking signal BR2 input from the MCU 202 is at the H potential, since the transistor 278a is turned on and the transistors 278b, 278c, 278d are all turned on, all of the motor control signals UL2, VL2, and WL2 input to the gate drive circuit 210 become the H potential. In this case, a short-circuit braking signal is input to the gate drive circuit 210 to apply a short-circuit brake to the stranded motor 76.

[0150] As Figure 20 shown, the Hall sensor 180 of the feed motor 32 and the Hall sensor 192 of the stranded motor 76 are connected to the motor rotation signal input source switching circuit 206. The motor rotation signal input source switching circuit 206 is connected to the motor rotation signal input port 202b of the MCU 202. The motor rotation signal input source switching circuit 206 inputs either the Hall sensor signals Hu1, Hv1, Hw1 from the feed motor 32 or the Hall sensor signals Hu2, Hv2, Hw2 from the stranded motor 76 to the motor rotation signal input port 202b of the MCU 202 in response to the switching signal SW output from the MCU 202.

[0151] It can also be as Figure 26As shown, the motor rotation signal input source switching circuit 206 is configured with a multiplexer 282. When the switching signal SW output from the MCU 202 is at the H potential, the multiplexer 282 outputs the Hall sensor signal Hu1 from the feeding motor 32 as the Hall sensor signal Hu to the MCU 202. When the switching signal SW output from the MCU 202 is at the L potential, the multiplexer 282 outputs the Hall sensor signal Hu2 from the stranding motor 76 as the Hall sensor signal Hu to the MCU 202. Additionally, for ease of understanding, only the structure corresponding to the Hall sensor signal Hu is described here, but the motor rotation signal input source switching circuit 206 has the same structure for other Hall sensor signals Hv and Hw.

[0152] Alternatively, it can also be as Figure 27 shown that the motor rotation signal input source switching circuit 206 is configured to include FETs 284, 286, and a NOT gate 288. When the switching signal SW output from the MCU 202 is at the H potential, the FET 284 is turned on and the FET 286 is turned off. In this case, the motor rotation signal input source switching circuit 206 outputs the Hall sensor signal Hu1 from the feeding motor 32 as the Hall sensor signal Hu to the MCU 202. When the switching signal SW output from the MCU 202 is at the L potential, the FET 284 is turned off and the FET 286 is turned on. In this case, the motor rotation signal input source switching circuit 206 outputs the Hall sensor signal Hu2 from the stranding motor 76 as the Hall sensor signal Hu to the MCU 202. Additionally, for ease of understanding, only the structure corresponding to the Hall sensor signal Hu is described here, but the motor rotation signal input source switching circuit 206 has the same structure for other Hall sensor signals Hv and Hw.

[0153] Alternatively, it can also be as Figure 28As shown, the motor rotation signal input source switching circuit 206 is configured to include NOR gates 290, 292, 294 and a NOT gate 296. When the switching signal SW output from the MCU 202 is at a high potential, since the NOR gate 290 inverts the Hall sensor signal Hu1 from the feeding motor 32 and outputs it, and the NOR gate 292 outputs a low potential, the NOR gate 294 outputs the Hall sensor signal Hu1 from the feeding motor 32. In this case, the motor rotation signal input source switching circuit 206 outputs the Hall sensor signal Hu1 from the feeding motor 32 to the MCU 202 as the Hall sensor signal Hu. When the switching signal SW output from the MCU 202 is at a low potential, since the NOR gate 290 outputs a low potential and the NOR gate 292 inverts the Hall sensor signal Hu2 from the stranding motor 76 and outputs it, the NOR gate 294 outputs the Hall sensor signal Hu2 from the stranding motor 76. In this case, the motor rotation signal input source switching circuit 206 outputs the Hall sensor signal Hu2 from the stranding motor 76 to the MCU 202 as the Hall sensor signal Hu. Additionally, for the sake of easy understanding, only the structure corresponding to the Hall sensor signal Hu is described here, but the motor rotation signal input source switching circuit 206 has the same structure for other Hall sensor signals Hv and Hw.

[0154] In addition, as Figure 20 shown, the Hall sensor 180 of the feeding motor 32 and the Hall sensor 192 of the stranding motor 76 are also connected to the general-purpose input / output port 202c of the MCU 202. The MCU 202 can monitor the Hall sensor signals Hu1, Hv1, Hw1 from the feeding motor 32 and the Hall sensor signals Hu2, Hv2, Hw2 from the stranding motor 76 input to the general-purpose input / output port 202c.

[0155] (Processing performed by the MCU 202)

[0156] When the trigger switch 9 is switched from off to on, the MCU 202 executes Figure 29 the processing. In Figure 29 the processing, the MCU 202 sequentially executes the first driving process of the feeding motor in S2 (refer to Figure 30 ), the first driving process of the stranding motor in S4 (refer to Figure 31 ), the second driving process of the feeding motor in S6 (refer to Figure 32 ), the second driving process of the stranding motor in S8 (refer to Figure 35 ), and the third driving process of the stranding motor in S10 (refer to Figure 36 ).

[0157] (First driving process of the feeding motor)

[0158] The following refers to Figure 30 to describe in detail the first driving process of the feeding motor. In S12, the MCU202 outputs a high potential as the switching signal SW, and switches the motor control signal output destination switching circuit 204 and the motor rotation signal input source switching circuit 206 to the feeding motor 32 side respectively.

[0159] In S14, the MCU202 outputs the motor control signals UH, VH, WH, UL, VL, and WL to reverse-rotate the feeding motor 32. As a result, the feeding motor 32 rotates in the reverse direction to start the feeding process of feeding the wire W.

[0160] In S16, the MCU202 stands by until the feeding amount of the wire W reaches a predetermined value. For example, the feeding amount of the wire W can be calculated by counting the Hall sensor signals Hu, Hv, and Hw. If the feeding amount of the wire W reaches the predetermined value (becomes "yes"), the process proceeds to S18.

[0161] In S18, the MCU202 outputs a short-circuit braking signal as the motor control signals UH, VH, WH, UL, VL, and WL to stop the feeding motor 32. In addition, the MCU202 outputs a high potential as the braking signal BR1. Thereby, braking is applied to the feeding motor 32. After the process of S18, Figure 30 the process ends.

[0162] (First driving process of the stranding motor)

[0163] The following refers to Figure 31 to describe in detail the first driving process of the stranding motor. In S22, the MCU202 outputs a low potential as the switching signal SW, and switches the motor control signal output destination switching circuit 204 and the motor rotation signal input source switching circuit 206 to the stranding motor 76 side respectively.

[0164] In S24, the MCU202 outputs the motor control signals UH, VH, WH, UL, VL, and WL to rotate the stranding motor 76 forward. As a result, the stranding motor 76 rotates forward to start the front-end holding process of holding the front end of the wire W.

[0165] In S26, the MCU202 stands by until the front end of the wire W is held. It is possible to determine whether the front end of the wire W is held based on the detection signal of the gripping detection sensor 138. If the front end of the wire W is held (becomes "yes"), the process proceeds to S28.

[0166] In S28, the MCU202 outputs a short-circuit braking signal as the motor control signals UH, VH, WH, UL, VL, and WL to stop the stranding motor 76. In addition, the MCU202 outputs an H potential as the braking signal BR2. Thereby, braking is applied to the stranding motor 76. After the process of S28, Figure 31 the process ends.

[0167] (Feeding motor second drive process)

[0168] The following refers to Figure 32 to describe the details of the feeding motor second drive process. In S32, the MCU202 outputs an H potential as the switching signal SW, and switches the motor control signal output destination switching circuit 204 and the motor rotation signal input source switching circuit 206 to the feeding motor 32 side.

[0169] In S34, the MCU202 outputs the motor control signals UH, VH, WH, UL, VL, and WL to rotate the feeding motor 32 forward. Thereby, the feeding motor 32 rotates forward to start the pulling-back process of pulling back the steel wire W.

[0170] In S36, the MCU202 determines whether the elapsed time since the start of driving the feeding motor 32 in S34 (hereinafter also referred to as the feeding motor driving time) is equal to or more than a predetermined upper limit time. When the feeding motor driving time is equal to or more than the upper limit time in S36 ("Yes" case), the MCU202 determines that the feeding motor 32 has not rotated normally due to some abnormality, and executes an error process in S38. When the feeding motor driving time is less than the upper limit time in S36 ("No" case), the process proceeds to S40.

[0171] In S40, the MCU202 determines whether the pulling-back amount of the steel wire W is equal to or more than a predetermined upper limit value. For example, the pulling-back amount of the steel wire W can be calculated by counting the Hall sensor signals Hu, Hv, and Hw. When the pulling-back amount of the steel wire W is equal to or more than the upper limit value in S40 ("Yes" case), the MCU202 determines that the front end of the steel wire W is not normally held, and executes an error process in S38. When the pulling-back amount of the steel wire W is less than the upper limit value in S40 ("No" case), the process proceeds to S42.

[0172] In the process after S42, the MCU202 determines whether the pulling-back of the steel wire W has been completed based on the history value of the current value I flowing in the feeding motor 32 detected by the current detection circuit 216. The following refers to Figure 33 and Figure 34 to describe the change over time of the current value I flowing in the feeding motor 32.

[0173] In Figure 33In the figure, the change of the current value I over time in the case of a larger diameter of the steel bar is represented by a dashed line, and the change of the current value I over time in the case of a smaller diameter of the steel bar is represented by a solid line. As Figure 33 shown, if the feeding motor 32 starts to drive at time t0, the current value I increases to the peak value of the starting current at time t1 and then gradually decreases. After that, when the wire W starts to closely adhere to the steel bar R, the current value I changes to increase again (at time t2 in the case of a larger diameter of the steel bar and at time t4 in the case of a smaller diameter of the steel bar). After that, when the wire W is completely adhered to the steel bar R, the current value I changes to decrease again (at time t3 in the case of a larger diameter of the steel bar and at time t5 in the case of a smaller diameter of the steel bar).

[0174] Figure 34 Schematically represents Figure 33 the relationship between the wire W and the steel bar R at times t1, t2, t3, t4, and t5. In the case of a larger diameter of the steel bar, the timing when the wire W starts to closely adhere to the steel bar R is earlier (time t2), and the timing when the wire W completes the adhesion to the steel bar R is also earlier (time t3). Therefore, as Figure 33 shown by the solid line in the figure, the current value I changes from decreasing to increasing at an earlier timing, and then also changes from increasing to decreasing at an earlier timing. In addition, the minimum value Imin1 of the current value I after exceeding the peak value of the starting current does not become a very low value, and the increase amount ΔI1 of the subsequent current value I does not become a very large value. In contrast, as Figure 34 shown, in the case of a smaller diameter of the steel bar, the timing when the wire W starts to closely adhere to the steel bar R is later (time t4), and the timing when the wire W completes the adhesion to the steel bar R is also later (time t5). Therefore, as Figure 33 shown by the dashed line in the figure, the current value I changes from decreasing to increasing at a later timing, and then also changes from increasing to decreasing at a later timing. In addition, the minimum value Imin2 of the current value I after exceeding the peak value of the starting current becomes a lower value, and the increase amount ΔI2 of the subsequent current value I becomes a larger value.

[0175] Therefore, in this embodiment, the MCU202 discriminates the diameter of the steel bar based on the timing when the current value I changes from decreasing to increasing after exceeding the peak value of the starting current, that is, the timing when the time change rate dI / dt of the current value I becomes above the time change rate threshold α. In addition, the MCU202 changes the determination condition for the completion of the pull-back based on the discriminated diameter of the steel bar.

[0176] In Figure 32In S42, the MCU 202 determines whether the current value I exceeds the peak value of the starting current. For example, when the driving time of the feeding motor exceeds a predetermined lower limit time, the MCU 202 determines that the current value I exceeds the peak value of the starting current. When the current value I does not exceed the peak value of the starting current (the case of "no"), the process returns to S36. When it exceeds the peak value of the starting current (the case of "yes"), the process proceeds to S44.

[0177] In S44, the MCU 202 determines whether the discrimination of the steel bar diameter has been completed. When the discrimination of the steel bar diameter has not been performed (the case of "no"), the process proceeds to S46. When the discrimination of the steel bar diameter has been performed (the case of "yes"), the process proceeds to S56.

[0178] In S46, the MCU 202 updates the minimum value Imin of the current value I of the feeding motor 32. Specifically, when the currently detected current value I is lower than the stored minimum value Imin, the MCU 202 replaces the minimum value Imin with the current value I.

[0179] In S48, the MCU 202 calculates the time change rate dI / dt of the current value I of the feeding motor 32.

[0180] In S50, the MCU 202 determines whether the time change rate dI / dt calculated in S48 is equal to or greater than the time change rate threshold α. The time change rate threshold α is a preset positive constant. When dI / dt is less than α (the case of "no"), the process returns to S36. When dI / dt is equal to or greater than α (the case of "yes"), the process proceeds to S52.

[0181] In S52, the MCU 202 determines the steel bar diameter based on the feeding motor driving time. For example, when the feeding motor driving time at the moment of S52 is less than the first predetermined time, the MCU 202 determines that the steel bar diameter is a large diameter. In addition, when the feeding motor driving time at the moment of S52 is equal to or greater than the first predetermined time and less than the second predetermined time greater than the first predetermined time, the MCU 202 determines that the steel bar diameter is a medium diameter. And when the feeding motor driving time at the moment of S52 is equal to or greater than the second predetermined time, the MCU 202 determines that the steel bar diameter is a small diameter.

[0182] In S54, the MCU 202 sets the increase amount threshold ΔImax of the current value I based on the steel bar diameter discriminated in S52. The larger the steel bar diameter, the smaller the increase amount threshold ΔImax is set.

[0183] In S56, the MCU 202 calculates the increase amount ΔI of the current value I by subtracting the updated minimum value Imin in S46 from the current current value I.

[0184] In S58, the MCU 202 determines whether the increase amount ΔI calculated in S56 is equal to or greater than the increase amount threshold ΔImax set in S54. When the increase amount ΔI is less than the increase amount threshold ΔImax (the case of "No"), the process returns to S36.

[0185] In S58, when the increase amount ΔI is equal to or greater than the increase amount threshold ΔImax (the case of "Yes"), the MCU 202 determines that the retraction of the steel wire W is completed, and the process proceeds to S60.

[0186] In S60, the MCU 202 outputs short-circuit braking signals as the motor control signals UH, VH, WH, UL, VL, and WL to stop the feeding motor 32. In addition, the MCU 202 outputs an H potential as the braking signal BR1. Thereby, braking is applied to the feeding motor 32. After the process of S60, Figure 32 the process ends.

[0187] In addition, in Figure 32 S52, the MCU 202 discriminates the diameter of the reinforcing bar based on the elapsed time (feeding motor driving time) since the start of the driving of the feeding motor 32 in S34. Differently, the MCU 202 may be configured such that, when determining the timing of the peak value of the starting current of the feeding motor 32, the diameter of the reinforcing bar is discriminated in S52 based on the elapsed time since the peak value of the starting current.

[0188] In Figure 32 the process, the MCU 202 determines the minimum value Imin after the current value I flowing through the feeding motor 32 exceeds the peak value of the starting current, and stops the feeding motor 32 when the increase amount ΔI relative to the minimum value Imin reaches the increase amount threshold ΔImax. Differently, the MCU 202 may be configured such that, when the elapsed time since the timing at which the time change rate dI / dt of the current value I flowing through the feeding motor 32 in S50 reaches the time change rate threshold α reaches the time threshold, the feeding motor 32 is stopped. In this case, by setting the time threshold to a smaller value when the diameter of the reinforcing bar determined in S52 is larger, and setting the time threshold to a larger value when the diameter of the reinforcing bar is smaller, Figure 32 the stop condition of the feeding motor 32 can be changed according to the diameter of the reinforcing bar in the same manner as in

[0189] In Figure 32In the process of, the MCU 202 determines the diameter of the steel bar based on the historical value of the current value I flowing in the feeding motor 32 related to the time t, and changes the stop condition of the feeding motor 32. The MCU 202 may also be different, for example, it determines the diameter of the steel bar based on the historical value of the current value I flowing in the feeding motor 32 related to the number of rotations N of the feeding motor 32, and changes the stop condition of the feeding motor 32. For example, the MCU 202 may also be configured as follows: calculate the change rate dI / dN of the current value I of the feeding motor 32 related to the number of rotations N of the feeding motor 32 in S48, and determine in S50 whether the calculated change rate dI / dN has reached the change rate threshold β.

[0190] (Stranding motor second drive process)

[0191] The following refers to Figure 35 Describe the details of the stranding motor second drive process. In S62, the MCU 202 outputs an L potential as the switching signal SW, and switches the motor control signal output destination switching circuit 204 and the motor rotation signal input source switching circuit 206 to the stranding motor 76 side.

[0192] In S64, the MCU 202 outputs motor control signals UH, VH, WH, UL, VL, WL to rotate the stranding motor 76 forward. Thus, the processes of maintaining the rear end of the steel wire W during the forward rotation of the stranding motor 76, cutting the steel wire W, pulling the steel wire W, and stranding the steel wire W are sequentially executed.

[0193] In S66, the MCU 202 waits until the stranding of the steel wire W is completed. For example, when the current value detected by the current detection circuit 216 becomes equal to or greater than a predetermined value corresponding to the set value of the bundling force of the steel wire W, the MCU 202 determines that the stranding of the steel wire W is completed. This predetermined value can be set as a value different according to the diameter of the steel bar determined in the second drive process of the feeding motor, or can be set as a constant value regardless of the diameter of the steel bar. If the stranding of the steel wire W is completed (becomes "yes"), the process proceeds to S68.

[0194] In S68, the MCU 202 outputs a short-circuit braking signal as the motor control signals UH, VH, WH, UL, VL, WL to stop the stranding motor 76. Thus, braking is applied to the stranding motor 76. After S68, Figure 35 the process ends.

[0195] (Stranding motor third drive process)

[0196] The following refers to Figure 36 Describe the details of the stranding motor third drive process.

[0197] In S72, the MCU 202 outputs motor control signals UH, VH, WH, UL, VL, and WL to reverse-rotate the stranding motor 76. Thereby, the stranding motor 76 rotates in the reverse direction, and thus an initial state restoration process in which the stranding mechanism 30 returns to the initial state starts.

[0198] In S74, the MCU 202 stands by until the stranding mechanism 30 returns to the initial state. It is possible to determine whether the stranding mechanism 30 has returned to the initial state based on the detection signal of the initial state detection sensor 136. If the stranding mechanism 30 returns to the initial state (becomes "Yes"), the process proceeds to S76.

[0199] In S76, the MCU 202 outputs a short-circuit braking signal as the motor control signals UH, VH, WH, UL, VL, and WL to stop the stranding motor 76. Thereby, braking is applied to the stranding motor 76. After S76, Figure 36 the process ends.

[0200] As described above, in one or more embodiments, the steel bar tying machine 2 includes a feeding motor 32, a current detection circuit 216 (an example of a current sensor) that detects the current flowing in the feeding motor 32, and an MCU 202 (an example of a control unit) that controls the operation of the feeding motor 32. The steel bar tying machine 2 can execute the following processes: a feeding process of sending out the wire W around the steel bar R by driving the feeding motor 32; a holding process of holding the vicinity of the front end of the wire W; a pulling-back process of pulling back the wire W by driving the feeding motor 32; a cutting process of cutting the wire W; and a stranding process of stranding the wire W. The MCU 202 is configured to determine the diameter of the steel bar R based on the historical value of the current value I flowing in the feeding motor 32 during the pulling-back process.

[0201] In the above-described pulling-back process, the wire W sent around the steel bar R is reduced in diameter and closely adheres to the steel bar R. At this time, when the wire W starts to closely adhere to the steel bar R and when the wire W finishes closely adhering to the steel bar R, the characteristics of the current value I flowing in the feeding motor 32 change. When the diameter of the steel bar R is large, the timing when the wire W starts to closely adhere to the steel bar R and the timing when the wire W finishes closely adhering to the steel bar R are earlier. On the contrary, when the diameter of the steel bar R is small, the timing when the wire W starts to closely adhere to the steel bar R and the timing when the wire W finishes closely adhering to the steel bar R are later. In the above-described steel bar tying machine 2, focusing on the fact that the characteristics of the current value I flowing in the feeding motor 32 during the pulling-back process of the wire W are different according to the diameter of the steel bar R, the diameter of the steel bar R is determined based on the historical value of the current value I flowing in the feeding motor 32. By adopting such a structure, it is possible to execute operations corresponding to the diameter of the steel bar R without providing a determination mechanism for determining the diameter of the steel bar R.

[0202] In one or more embodiments, the MCU 202 is configured to calculate the time change rate dI / dt of the current value I flowing through the feeding motor 32 after exceeding the peak value of the starting current of the feeding motor 32 in the retracting process, and determine the diameter of the steel bar R based on the timing when the time change rate dI / dt reaches the time change rate threshold α.

[0203] In the retracting process, the current value I flowing through the feeding motor 32 gradually decreases after increasing to the peak value of the starting current. Thereafter, the current value I flowing through the feeding motor 32 changes from decreasing to increasing at the timing when the wire W starts to closely adhere to the steel bar R, and changes from increasing to decreasing again at the timing when the wire W completes the close adhesion to the steel bar R. According to the above structure, at the timing when the current value I flowing through the feeding motor 32 changes from decreasing to increasing after exceeding the peak value of the starting current, that is, at the timing when the wire W starts to closely adhere to the steel bar R, the diameter of the steel bar R can be determined. By adopting such a structure, the operation of the latter half of the retracting process can be executed corresponding to the determined diameter of the steel bar R.

[0204] In one or more embodiments, the MCU 202 is configured to stop the feeding motor 32 when a stop condition is satisfied in the retracting process. The MCU 202 is configured to change the stop condition corresponding to the determined diameter of the steel bar R.

[0205] In the retracting process, when the diameter of the steel bar R is larger, since the wire W completes the close adhesion to the steel bar R earlier, it is necessary to stop the feeding motor 32 earlier accordingly. On the contrary, when the diameter of the steel bar R is smaller, the wire W completes the close adhesion to the steel bar R later, and it is necessary to stop the feeding motor 32 later accordingly. According to the above structure, since the stop condition is changed corresponding to the determined diameter of the steel bar R, the feeding motor 32 can be stopped at an appropriate timing.

[0206] In one or more embodiments, the MCU 202 is configured to determine the minimum value Imin of the current value I flowing through the feeding motor 32 after exceeding the peak value of the starting current of the feeding motor 32 in the retracting process, and calculate the increase amount ΔI of the current value I flowing through the feeding motor 32 with respect to the minimum value Imin. The stop condition includes the condition that the increase amount ΔI reaches the increase amount threshold ΔImax. The MCU 202 is configured to change the increase amount threshold ΔImax corresponding to the determined diameter of the steel bar R.

[0207] In the pulling-back process, when the diameter of the steel bar R is large, since the wire W starts to closely adhere to the steel bar R at an earlier timing, the current value I flowing in the feeding motor 32 does not decrease significantly after exceeding the peak value of the starting current. Therefore, the minimum value Imin of the current value I flowing in the feeding motor 32 after exceeding the peak value of the starting current is relatively large, and the increase amount ΔI of the current value I until the wire W completes the close adhesion to the steel bar R is small. On the contrary, when the diameter of the steel bar R is small, since the wire W starts to closely adhere to the steel bar R at a later timing, the current value I flowing in the feeding motor 32 decreases significantly after exceeding the peak value of the starting current. Therefore, the minimum value Imin of the current value I flowing in the feeding motor 32 after exceeding the peak value of the starting current is relatively small, and the increase amount ΔI of the current value I until the wire W completes the close adhesion to the steel bar R is large. According to the above structure, since the increase amount threshold ΔImax is changed corresponding to the determined diameter of the steel bar R, the feeding motor 32 can be stopped at an appropriate timing.

[0208] In one or more embodiments, the steel bar bundling machine 2 includes a feeding motor 32, a current detection circuit 216 (an example of a current sensor) that detects the current flowing in the feeding motor 32, and an MCU 202 (an example of a control unit) that controls the operation of the feeding motor 32. The steel bar bundling machine 2 can perform the following processes: a feeding process of feeding the wire W around the steel bar R by driving the feeding motor 32; a gripping process of gripping the vicinity of the front end of the wire W; a pulling-back process of pulling back the wire W by driving the feeding motor 32; a cutting process of cutting the wire W; and a twisting process of twisting the wire W. The MCU 202 is configured to stop the feeding motor 32 when a stop condition is satisfied in the pulling-back process. The MCU 202 is configured to change the stop condition corresponding to the historical value of the current value I flowing in the feeding motor 32 in the pulling-back process.

[0209] In the above steel bar bundling machine 2, focusing on the situation that the characteristics of the current value I flowing in the feeding motor 32 in the pulling-back process of the wire W are different according to the diameter of the steel bar R, the stop condition of the feeding motor 32 is changed based on the historical value of the current value I flowing in the feeding motor 32. By adopting such a structure, it is possible to perform operations corresponding to the diameter of the steel bar R without providing a discrimination mechanism for discriminating the diameter of the steel bar R.

[0210] In one or more embodiments, the MCU 202 is configured to calculate the time change rate dI / dt of the current value I flowing in the feeding motor 32 after exceeding the peak value of the starting current of the feeding motor 32 in the pulling-back process, and change the stop condition corresponding to the timing when the time change rate dI / dt reaches the time change rate threshold α.

[0211] Based on the above structure, the timing when the current value I flowing in the feeding motor 32 changes from decreasing to increasing after exceeding the peak value of the starting current, that is, the timing when the wire W starts to closely adhere to the steel bar R, the stop condition of the feeding motor 32 can be changed.

[0212] In one or more embodiments, the MCU 202 is configured to determine the minimum value Imin of the current value I flowing in the feeding motor 32 after exceeding the peak value of the starting current of the feeding motor 32 during the retracting process, and calculate the increase amount ΔI of the current value I flowing in the feeding motor 32 with respect to the minimum value Imin. The stop condition includes the condition that the increase amount ΔI reaches the increase amount threshold ΔImax. The MCU 202 is configured to change the increase amount threshold ΔImax corresponding to the timing when the time change rate dI / dt reaches the time change rate threshold α.

[0213] Based on the above structure, since the increase amount threshold ΔImax is changed corresponding to the timing when the time change rate dI / dt of the current value I flowing in the feeding motor 32 reaches the time change rate threshold α, the feeding motor 32 can be stopped at an appropriate timing.

Claims

1. A steel bar bundling machine, wherein, the steel bar bundling machine includes: a feeding motor; a current sensor that detects the current flowing in the feeding motor; and a control unit that controls the operation of the feeding motor, the steel bar bundling machine is capable of performing the following processes: a feeding process of feeding a steel wire around a steel bar by driving the feeding motor; a gripping process of gripping near the front end of the steel wire; a pulling-back process of pulling back the steel wire by driving the feeding motor; a cutting process of cutting the steel wire; and a twisting process of twisting the steel wire, the control unit is configured to determine the diameter of the steel bar based on the historical value of the current value flowing in the feeding motor during the pulling-back process.

2. The steel bar bundling machine according to claim 1, wherein, the control unit is configured to, during the pulling-back process, calculate the time change rate of the current value flowing in the feeding motor after exceeding the peak value of the starting current of the feeding motor, and determine the diameter of the steel bar based on the timing when the time change rate reaches a time change rate threshold.

3. The steel bar bundling machine according to claim 1, wherein, the control unit is configured to stop the feeding motor when a stop condition is satisfied during the pulling-back process, the control unit is configured to change the stop condition corresponding to the determined diameter of the steel bar.

4. The steel bar bundling machine according to claim 2, wherein, the control unit is configured to stop the feeding motor when a stop condition is satisfied during the pulling-back process, the control unit is configured to change the stop condition corresponding to the determined diameter of the steel bar.

5. The steel bar bundling machine according to claim 4, wherein, the control unit is configured to determine the minimum value of the current value flowing in the feeding motor after exceeding the peak value of the starting current of the feeding motor during the pulling-back process, and calculate the increase amount of the current value flowing in the feeding motor relative to the minimum value, the stop condition includes the condition that the increase amount reaches an increase amount threshold, the control unit is configured to change the increase amount threshold corresponding to the determined diameter of the steel bar.

6. A steel bar bundling machine, wherein, the steel bar bundling machine includes: a feeding motor; a current sensor that detects the current flowing in the feeding motor; and a control unit that controls the operation of the feeding motor, the steel bar bundling machine is capable of performing the following processes: a feeding process of feeding a steel wire around a steel bar by driving the feeding motor; a gripping process of gripping near the front end of the steel wire; a pulling-back process of pulling back the steel wire by driving the feeding motor; a cutting process of cutting the steel wire; and a twisting process of twisting the steel wire, the control unit is configured to stop the feeding motor when a stop condition is satisfied during the pulling-back process, the control unit is configured to change the stop condition corresponding to the historical value of the current value flowing in the feeding motor during the pulling-back process.

7. The steel bar bundling machine according to claim 6, wherein, the control unit is configured to calculate a time change rate of the current value flowing through the feeding motor after exceeding a peak value of a starting current of the feeding motor in the pulling-back process, and change the stop condition corresponding to a timing when the time change rate reaches a time change rate threshold value.

8. The steel bar bundling machine according to claim 7, wherein, the control unit is configured to determine a minimum value of the current value flowing through the feeding motor after exceeding the peak value of the starting current of the feeding motor in the pulling-back process, and calculate an increase amount of the current value flowing through the feeding motor with respect to the minimum value, the stop condition includes a condition that the increase amount reaches an increase amount threshold value, the control unit is configured to change the increase amount threshold value corresponding to the timing when the time change rate reaches the time change rate threshold value.

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