Working machine and method for manufacturing a spindle used in the working machine

Abstract

Durability and machinability are improved. A corner section 46C of a plate coupling section 46 is chamfered on a support section 43 of a spindle 41 of an impact tool 1. This prevents stress concentration at the corner section 46C and simultaneously increases the durability of the impact tool 1. A chamfered hole section 47, whose depth direction is front-to-back, extends from a rear surface of a rear support plate 44 to a rear section of a front support plate 45. Furthermore, when viewed from the front-to-back direction, part of an inner circumferential surface of the chamfered hole section 47 coincides with the corner section 46C.In this way, by performing a hole opening machining (machining) using a drill on the support section 43 from the rear side over the entire thickness direction of the plate coupling section 46, the corner section 46C can be chamfered.

Description

Technical field

[0001] The present invention relates to a machine and a method for manufacturing a spindle used in the machine. General state of the art

[0002] In a machine described in patent document 1 below, a reduction machine formed from a planetary gear mechanism transmits the driving force of a motor to a striking mechanism, and the torque and impact force are transferred to a front-end tool, such as a screwdriver bit or the like, attached to the striking mechanism. This striking mechanism comprises a spindle rotated by the driving force of the motor, a hammer coupled to the spindle by means of a cam mechanism, and an anvil rotatably connected to the hammer by means of a striking claw.

[0003] Idler wheels are rotatably mounted on the spindle, forming a reduction mechanism. Specifically, the spindle has a shaft section and a pair of circular, disk-shaped wall sections extending radially outwards from the shaft section, with the outer circumferential sections of the two wall sections coupled to each other by a coupling section. The idler wheels are mounted between the two wall sections. State-of-the-art documents, patent documents

[0004] Patent Document 1: JP 2018-86723 A Brief description of the invention; Problem of the present invention

[0005] Due to the number of idler wheels incorporated, the coupling section connecting the two wall sections of the spindle, when viewed from the axial direction, is essentially fan-shaped with its center point at a radially inner end section. Viewed from the axial direction, the coupling section thus has a corner section that is convex towards the axis of the spindle. This corner section therefore experiences a stress concentration, meaning that if the coupling section is damaged, the service life of the spindle (the machine) may be reduced.

[0006] However, the stress concentration at the corner section can be prevented by chamfering the corner section. In this case, chamfering must be performed on the corner section of the coupling section located between the two wall sections, which may reduce the spindle's machinability. Therefore, for a machine tool that uses a spindle, a design that improves durability and machinability is desirable.

[0007] In light of the foregoing, the present invention is based on the objective of providing a machine and a method for manufacturing a spindle used in the machine, with which durability and ease of use can be improved. Means of solving the task

[0008] In one or more embodiments of the present invention, a machine comprises a motor, a spindle rotated by the drive of the motor, and a front-end tool holding section which holds a front-end tool and is driven by the rotational force of the spindle, wherein the spindle is configured to have a first wall section extending radially outwards from the shaft section, a second wall section extending radially outwards from the shaft section and arranged axially opposite the first wall section, a coupling section which couples the first wall section and the second wall section to each other on a radially outer side of the shaft section between the first wall section and the second wall section, and has a chamfered corner section.which, when viewed from the axial direction, is convex towards the side of the wave section, and includes a chamfered hole section formed with a depth direction as the axial direction from one of the first wall section and the second wall section to the other of the first wall section and the second wall section, and of which part of an inner circumferential surface coincides with the corner section when viewed from the axial direction.

[0009] In one or more embodiments of the present invention, the machine in which the chamfer hole section extends through one of the first wall section and the second wall section, and the chamfer hole section formed in the other of the first wall section and the second wall section is formed in the form of a recess that opens towards one of the first wall section and the second wall section.

[0010] One or more embodiments of the present invention are a working machine in which the chamfer hole section passes through the first wall section and the second wall section.

[0011] One or more embodiments of the present invention are a machine in which the chamfer hole section is circular when viewed from the axial direction.

[0012] In one or more embodiments of the present invention, the machine in which the chamfer hole section, when viewed from the axial direction, is formed in the form of an elongated hole, the longitudinal direction of which is the circumferential direction of the spindle.

[0013] In one or more embodiments of the present invention, the working machine is configured such that it includes a pair of side surfaces which, when viewed from the axial direction, extend in a direction in which they increasingly approach each other towards the radially inner side of the shaft section, and a corner section which is formed at a part in which the pair of side surfaces intersect each other, wherein an R-approach section is formed at a boundary section between the side surfaces and inner circumferential surfaces of the first wall section and the second wall section.

[0014] In one or more embodiments of the present invention, a working machine is formed in which, when viewed from the axial direction, a part of the chamfered hole section overlaps with the shaft section.

[0015] In one or more embodiments of the present invention, the machine comprises a front-end tool located on one side of the spindle in the axial direction, the second wall section being arranged on one side of the first wall section in the axial direction, a thick section being provided on the second wall section, and the thick section being superimposed on the corner section when viewed from the axial direction.

[0016] In one or more embodiments of the present invention, the working machine is in which the coupling section is provided at three locations between the first wall section and the second wall section, wherein the coupling sections are arranged at uniform intervals in the circumferential direction of the shaft section.

[0017] In one or more embodiments of the present invention, a working machine is arranged in which three transmission elements are arranged between the first wall section and the second wall section, which transmit the driving force of the motor, wherein the chamfer hole section, when viewed from the axial direction with respect to the corner section, is arranged adjacent to the radially inner side of the shaft section, and the transmission elements and the coupling sections are arranged alternately in the circumferential direction of the shaft section.

[0018] One or more embodiments of the present invention comprise a method for manufacturing a spindle used in a machine tool, wherein the spindle is designed to include a shaft section, a first wall section extending radially outwards from the shaft section, a second wall section extending radially outwards from the shaft section and arranged axially opposite the first wall section, a coupling section that couples the first wall section and the second wall section to each other on the radially outer side of the shaft section between the first wall section and the second wall section and has a chamfered corner section, and a chamfered hole section.which is formed with a depth direction as the axial direction on the first wall section and the second wall section and of which part of an inner circumferential surface, viewed from the axial direction, coincides with the corner section, comprising a first step in which the shaft section and a projecting section extending radially outwards from the shaft section are formed, a second step in which the projecting section is machined from the radially outer side by a face milling cutter, thus forming the first wall section, the second wall section and the coupling section on the projecting section, and a third step in which the projecting section is machined from one side or the other in the axial direction by a drill or a face milling cutter, thus forming the chamfer hole section and chamfering the corner section. Effect of the invention

[0019] According to one or more embodiments of the present invention, durability and machinability can be improved. Brief description of the characters Fig. Figure 1 is a vertical sectional view of a striking tool according to the present embodiment. Fig. Figure 2 is a vertical sectional view showing the upper section of the impact tool. Fig. 1 shows enlarged. Fig. 3(A) is a right side view of a spindle made of Fig. 2, and Fig. 3(B) is a front sectional view showing the interior of a support section of the spindle of (A) (sectional view at line 3B-3B from Fig. 3(A)). Fig. Figure 4 is a perspective view from the oblique front right of a rear section of the support section in a broken-up state. Fig. 3(B). Fig. Figure 5 is a sectional view of a lower plate coupling section and a chamfer hole section made of Fig. 3(B) from the right. Fig. 6 is a Fig. 4. Corresponding perspective view of the rear section of the support section of a spindle of a comparative example. Fig. 7 is a Fig. 5 corresponding sectional view, which is a modified example of the one in Fig. The chamfered hole section shown in section 5 is shown. Fig. 8 is a Fig. 5 corresponding sectional view, which is a further variation example of the one in Fig. The chamfered hole section shown in section 5 is shown. Fig. 9 is a Fig. 3(B) corresponding sectional view, which is a modified example of the shape of the in Fig. 3(B) shows the chamfered hole section. embodiment of the invention

[0020] With reference to the figures, a striking tool 1 is described below as a working machine of the present embodiment. For the sake of simplicity, the arrows TOP, FRONT, and RIGHT shown in the figures denote a top, a front, and a right side of the striking tool 1, respectively. Unless otherwise specified, when the following description refers to an top-bottom direction, a front-back direction, and a left-right direction, this refers to the top-bottom direction, the front-back direction, and the left-right direction of the striking tool 1.

[0021] As in Fig. 1 and Fig. As shown in Figure 2, the impact tool 1 is designed as an electrically driven tool in which a rotational force and an impact force are transferred to a front-end tool 70 such as a screw bit or the like, which is attached to a front-end section of the impact tool 1, in order to perform tightening operations and the like.

[0022] The impact tool 1 is designed with a housing 10 forming the outer contour of the impact tool 1, a motor 20 housed in the housing 10, and a drive force transmission mechanism 30 that transmits the drive force of the motor 20 to the front-end tool 70. The individual design elements of the impact tool 1 are described below.

[0023] (Housing 10) The housing 10 is essentially formed in the shape of a hollow I. Specifically, the housing 10 comprises an upper housing section 10A, which forms the upper end section of the housing 10 and extends in a front-to-back direction; a handle section 10B, which extends downwards from a front-to-back central section of the upper housing section 10A; and a lower housing section 10C, which forms the lower end section of the housing 10. The housing 10 is formed by several housing elements, and the housing 10 is formed by assembling these housing elements.

[0024] A trigger 12 is provided at the upper end of the grip section 10B, the trigger 12 being designed to project forward from the grip section 10B and to be operated by pulling it backward. A switching mechanism 14 is provided on the rear side of the trigger 12 on the grip section 10B. The switching mechanism 14 has a switch (not shown), which is switched on and off by pulling the trigger 12.

[0025] A control unit 16 is provided in the lower housing section 10C. The switch of the switching mechanism 14 is electrically connected to the control unit 16 and outputs a signal to the control unit 16 corresponding to the operating state of the trigger 12. A battery 18 is also detachably attached to the lower housing section 10C. The battery 18 is electrically connected to the control unit 16, and electrical current is supplied to the motor 20 described below via the battery 18.

[0026] (Motor 20) The motor 20 is mounted in the rear end section of the upper housing section 10A and is electrically connected to the control unit 16. The motor 20 comprises a drive shaft 21, the axial direction of which is front-to-back, a rotor 22 rotatably coupled to the drive shaft 21 as an integral part, and a substantially cylindrical stator 23, which is arranged radially outside the rotor 22.

[0027] The rear end section of the drive shaft 21 is rotatably mounted by a first motor shaft bearing 24 fixed to the housing 10. The front end section of the drive shaft 21, in turn, is rotatably mounted by a second motor shaft bearing 26, the second motor shaft bearing 26 being fixed to a gearbox housing 25 located inside the upper housing section 10A. The gearbox housing 25 is essentially formed in the shape of a stepped cylinder, the axial direction of which is front-to-back, with the second motor shaft bearing 26 being essentially inserted into the central section of the gearbox housing 25. The front end section of the drive shaft 21 projects forward relative to the second motor shaft bearing 26 and is located inside the gearbox housing 25.

[0028] (Drive force transmission mechanism 30) The drive force transmission mechanism 30 is designed with a rotary impact mechanism 40, which transfers rotational force and impact force to the front end tool 70, and a reduction mechanism 32, which reduces the rotational force of the motor 20 and transmits it to the rotary impact mechanism 40.

[0029] (Reduction mechanism 32) The reduction mechanism 32 is designed as a planetary gear mechanism and is arranged inside the gearbox housing 25. Specifically, the reduction mechanism 32 is designed with a sun gear 33, which is fixed to the front end section of the drive shaft 21 of the motor 20, an annular ring gear 34 provided radially outwards from the sun gear 33, and several (in the present embodiment three) idler gears 35 serving as transmission elements, which are provided between the sun gear 33 and the ring gear 34.

[0030] The ring gear 34 is held against the gearbox housing 25 by a damper, and internal teeth are formed on the inner circumferential surface of the ring gear 34. The idler gears 35 are rotatably mounted on a support section 43, which serves as a projecting section of the spindle 41. Specifically, the idler gears 35 are located in a gearbox chamber 43A formed in the support section 43 (see Figure 1). Fig. 3(A)) is mounted and rotatably mounted on a needle roller 36 provided in the gearbox chamber 43A, with the front-back direction being the axial direction. The idler gears 35 are meshed with the sun gear 33 and the internal teeth of the ring gear 34. When the sun gear 33 rotates, the idler gears 35 rotate about the axis of the needle roller 36 and simultaneously circle the axis of the sun gear 33, resulting in the rotating design of the spindle 41. This design thus transmits the torque of the motor 20, reduced by the reduction mechanism 32, to the spindle 41, thereby operating the rotary impact mechanism 40.

[0031] (Rotary impact mechanism 40) The rotary impact mechanism 40 is designed with the spindle 41, a hammer 50 and an anvil 56 serving as a front-end tool holding section.

[0032] As in Fig. As shown in Figures 3(A) and (B), the spindle 41 has a substantially cylindrical spindle shaft 42 serving as a shaft section, the axial direction of which is front-to-back, with the spindle shaft 42 being arranged on the same axis as the drive shaft 21 of the motor 20. Specifically, the sun gear 33 discussed above is inserted into the rear end section of the spindle shaft 42, and the rear end section of the spindle shaft 42 is rotatably mounted by a shaft bearing 60 provided in the gearbox housing 25. A support section 43, extending radially outwards from the spindle shaft 42, is provided at a rear end section on the outer circumferential section of the spindle shaft 42, with the idler gears 35 discussed above being rotatably mounted on the support section 43. The design of the support section 43 will be described later.

[0033] A portion of the spindle shaft 42 located aft of the support section 43 is referred to as the rear shaft section 42A (an element that is broadly considered the first shaft section), and a portion of the spindle shaft 42 located aft of the support section 43 is referred to as the front shaft section 42B (an element that is broadly considered the second shaft section). The outer diameter of the rear shaft section 42A is slightly smaller than the outer diameter of the front shaft section 42B. A pair of spindle cam grooves 42C is formed in the outer circumferential surface of the front section of the front shaft section 42B. When viewed from the radial direction, the pair of spindle cam grooves 42C extends in a substantially V-shape.When viewed in cross-section from their longitudinal direction, the spindle cam grooves 42C are essentially formed in the shape of a semicircle that opens towards the radially outer side of the front shaft section 42B. Steel balls 52 are inserted into the front end section of the spindle cam grooves 42C in a rolling manner.

[0034] As in Fig. As shown in Figure 2, the hammer 50 is essentially formed in the form of a cylinder whose axial direction is front-to-back, with a through-hole 50A running through the middle section of the hammer 50 in the front-to-back direction. The front section of the front shaft section 42B of the spindle shaft 42 is guided through the through-hole 50A, so that the hammer 50 is rotatably mounted on the spindle 41.

[0035] A pair of hammer cam grooves 50B are formed in the inner circumferential surface of the through-hole 50A of the hammer 50. Viewed from the front, the hammer cam grooves 50B extend circumferentially around the hammer 50 and are open forwards. The rear end section of the hammer cam grooves 50B, viewed from the radially inner side of the hammer 50, is essentially V-shaped and open forwards. The two hammer cam grooves 50B are arranged 180 degrees apart circumferentially around the hammer 50. The steel balls 52 are inserted into the hammer cam grooves 50B so as to roll freely and rest against the rear end sections of the hammer cam grooves 50B.

[0036] In the rear surface of the hammer 50, in the radially central section, a rearwardly open receiving groove section 50D is formed. The receiving groove section 50D extends circumferentially around the hammer 50 and covers its entire circumference. A hammer spring 54, designed as a compression spring, is received in the receiving groove section 50D, and the hammer 50 is biased forward by the hammer spring 54. This holds the steel balls 52 in the front end section of the spindle cam grooves 42C and in the rear end section of the hammer cam grooves 50B, and rotatably couples the hammer 50 and the spindle 41 together in one piece. The design is such that the steel balls 52 roll in the spindle cam grooves 42C and hammer cam grooves 50B during operation of the rotary impact mechanism 40, so that the hammer 50 rotates relative to the spindle 41 and moves in a front-back direction.The rear end section of the hammer spring 54 is locked by a locking plate 62 arranged between the spindle 41 and the hammer 50.

[0037] Hammer claws 50E are integrally formed at several (three in the present embodiment) locations on the front surface of the hammer 50 (end surface on one side in the axial direction). The hammer claws 50E have a front-to-back thickness direction, are essentially formed in the form of a fan-shaped block that is convex towards the radially inner side of the hammer 50, and project forward from the hammer 50. The hammer claws 50E are arranged at regular intervals (of 120 degrees each) around the circumference of the hammer 50.

[0038] The anvil 56 is essentially formed in the form of a stepped cylinder open at the front and is arranged in front of the hammer 50. Specifically, a coupling shaft 56A is formed at the rear end section of the anvil 56, the diameter of which is smaller than that of the other parts, and the coupling shaft 56A is rotatably inserted into the front end section of the spindle shaft 42. The longitudinally central section of the anvil 56 is rotatably held by a sleeve 58 located at the front end section of the upper housing section 10A. The front-end tool 70 is attached to the inner section of the anvil 56 from the front in a manner that prevents it from rotating relative to the anvil 56.

[0039] Anvil claws 56B are provided at three locations on the outer circumferential section of the rear end of the anvil 56. The anvil claws 56B are essentially rectangular plates whose thickness is oriented front-to-back and project outwards in the radial direction of the anvil 56. The anvil claws 56B are arranged at regular intervals (of 120 degrees each) around the circumference of the anvil 56 and are positioned between the hammer claws 50E of the hammer 50. Thus, viewed from the front, the hammer claws 50E and the anvil claws 56B are arranged alternately around the circumference of the hammer 50.

[0040] When the hammer 50 rotates, the side surfaces of the hammer claws 50E come into contact with the side surfaces of adjacent anvil claws 56B in the direction of rotation, so that the hammer claws 50E and the anvil claws 56B engage in the circumferential direction of the hammer 50. This results in a configuration in which the rotational force of the hammer 50 is transferred to the anvil 56, and the anvil 56 rotates together with the front-end tool 70. When the rotational force (torque) required to rotate the front-end tool 70 exceeds a defined value, the hammer 50 moves backward relative to the anvil 56, such that the hammer claws 50E overcome the anvil claws 56B. When the hammer claws 50E overcome the anvil claws 56B, the hammer 50 rotates relative to the anvil 56, and by the hammer claws 50E striking the adjacent anvil claws 56B, the striking force is transferred from the hammer 50 to the anvil 56.

[0041] (Bearer section 43 of spindle 41) As in Fig. As shown in Figures 2 to 5, the support section 43 is formed with a rear support plate 44 serving as the first wall section, a front support plate 45 serving as the second wall section, plate coupling sections 46 serving as coupling sections at three points and a chamfered hole section 47.

[0042] The rear support plate 44 is essentially circular in shape with its thickness direction running from front to back and projects radially outwards from the front end section of the rear shaft section 42A. The front support plate 45, like the rear support plate 44, is essentially circular in shape with its thickness direction running from front to back and projects radially outwards from the rear end section of the front shaft section 42B. This results in the rear support plate 44 and the front support plate 45 being arranged opposite each other in the front-to-back direction at a defined distance, with the space between the rear support plate 44 and the front support plate 45 forming the gearbox chamber 43A for receiving the idler gears 35.The spindle shaft 42 is not provided in the gear chamber 43A, and the rear shaft section 42A and the front shaft section 42B are divided into a front and rear part at the support section 43, with the interior of the gear chamber 43A and the interior of the rear shaft section 42A and front shaft section 42B being connected.

[0043] The outer diameter of the rear support plate 44 and the outer diameter of the front support plate 45 are essentially the same. A thick section 45A is formed on a radially inner part of the front surface of the front support plate 45, the thickness of which is specified as greater than that of the other parts. The thickness of the thick section 45A of the front support plate 45 is slightly greater than that of the rear support plate 44.

[0044] The plate coupling sections 46 are arranged between the outer circumferential section of the rear support plate 44 and the outer circumferential section of the front support plate 45, coupling them together. The plate coupling sections 46 have a front-to-back thickness direction and are essentially formed in the form of a fan-shaped block that is convex towards the radially inner side of the spindle 41. Specifically, the plate coupling sections 46 are formed with a pair of inclined surfaces 46A, which form the two side surfaces of the plate coupling section 46 in the circumferential direction of the spindle 41, and an outer surface 46B, which forms the side surface of the plate coupling section 46 on the radially outer side of the spindle 41. The outer surface 46B is flush with the outer circumferential surface of the rear support plate 44 and the outer circumferential surface of the front support plate 45.Viewed from the front, the inclined surfaces 46A are inclined in a direction in which they increasingly approach each other towards the radially inner side of the spindle 41. Viewed from the front, the angle between the two inclined surfaces 46A is defined as an acute angle. The portion where the two inclined surfaces 46A intersect is formed as an acute corner section 46C. This corner section 46C is a chamfered corner, and the inner circumferential surface of the chamfered hole section 47 described below is flush with the corner section 46C. Therefore, the corner section 46C is not a so-called needle-sharp angle (an angle formed solely by lines), but rather an angle formed by a curved surface. Viewed from the front-to-back direction, the corner section 46C overlaps with the thick section 45A of the front support plate 45.An R-connection section 46D is formed at a boundary section between the inclined surfaces 46A and the inner circumferential surfaces of the rear support plate 44 and front support plate 45. The R-connection section 46D is formed in the shape of a circular arc and provides a smooth connection between the inclined surfaces 46A and the inner circumferential surfaces of the rear support plate 44 and front support plate 45.

[0045] In the rear support plate 44 and the front support plate 45, a through-hole bearing 48 is formed at three locations in the front-to-back direction. The bearing holes 48 are arranged between adjacent plate coupling sections 46 in the circumferential direction and at equal intervals around the spindle 41. The two end sections of the needle roller 36 are inserted into the bearing holes 48 in the front-to-back direction, thus supporting the needle roller 36 on the support section 43. The idler wheels 35, supported by the needle roller 36, are thus accommodated in the gearbox chamber 43A and arranged between adjacent plate coupling sections 46 in the circumferential direction. The idler wheels 35 and the plate coupling sections 46 are therefore arranged alternately next to each other around the spindle 41.

[0046] The chamfered hole section 47 is a hole whose depth direction is front-to-back. Viewed from the front-to-back direction, the chamfered hole section 47 is circular and extends from the rear surface of the rear support plate 44 to the rear section of the front support plate 45. This means that the chamfered hole section 47 is a hole running through the rear support plate 44 in a front-to-back direction and is designed as a concave blind hole that opens rearward in the front support plate 45.

[0047] The chamfered hole section 47, viewed from the front-to-back direction with respect to the plate coupling sections 46, is located adjacent to them on the radially inner side of the spindle 41, with a portion of the chamfered hole section 47 overlapping the corner section 46C of the plate coupling sections 46 before chamfering. Details will be described later, but the corner sections 46C are chamfered by machining a hole from the rear onto the support section 43 using a cutting tool such as a drill or the like, thus forming the chamfered hole section 47 in the rear support plate 44 and the front support plate 45, thereby chamfering the corner section 46C of the plate coupling sections 46. In this way, when viewed from the front-back direction, part of an inner circumferential surface of the chamfer hole section 47 coincides with the corner section 46C.In other words, the inner circumferential surface of the chamfered hole section 47 is flush with the corner section 46C. When viewed from the front-to-back direction, part of the chamfered hole section 47 also overlaps with the outer circumferential section of the front shaft section 42B of the spindle shaft 42.

[0048] (Method for manufacturing the spindle 41) In the manufacturing of the spindle 41, in a first step the spindle shaft 42 and the support section 43, which extends radially outwards from the spindle shaft 42 and does not have a gear chamber 43A (see the support section 43, which is in Fig. 3(A) is shown with the line interrupted by two points).

[0049] Next, in a second step, as described in Fig. Figure 3(A) shows that the central section of the support section 43, in the front-to-back direction, is machined from the radially outer side using a face milling cutter EM, thereby forming the rear support plate 44, the front support plate 45, and the plate coupling sections 46 on the support section 43 (second step). In this case, the machining operation on the support section 43 is carried out by appropriately changing the insertion direction of the face milling cutter EM into the support section 43. This forms the gearbox chamber 43A between the rear support plate 44 and the front support plate 45.In the second step, the R-approach section 46D is formed between the inclined surfaces 46A of the plate coupling sections 46 and the inner circumferential surfaces of the rear support plate 44 and front support plate 45, while the corner sections 46C of the plate coupling sections 46 are in the unchamfered state (see the radially inner end sections of the plate coupling sections 46, which are shown in . Fig. 3(B) with the line interrupted by two dots shown).

[0050] Next, in a third step, as described in Fig. Figure 5 shows that a hole formation operation is performed on the support section 43 using a drill DR, and the chamfer hole section 47 is formed in the support section 43, and the corner sections 46C of the plate coupling sections 46 are chamfered (third step). Specifically, the rear support plate 44 of the support section 43 is machined from the rear using the drill DR, thus forming the chamfer hole section 47 through the rear support plate 44. Then, the corner sections 46C of the plate coupling sections 46 of the support section 43 are machined to chamfer the corner sections 46C. Finally, the front support plate 45 of the support section 43 is machined from the rear to form the concave chamfer hole section 47. This chamfers the corner sections 46C along the entire thickness direction of the plate coupling sections 46.After or during the formation of the chamfered hole section 47 in the support section 43, a further drill is used to perform a hole formation operation on the support section 43 in order to form the bearing holes 48 in the support section 43.

[0051] (Mode of operation and effect) Next, the mode of operation and the effect of the present embodiment will be described.

[0052] When the motor 20 of the impact tool 1, designed as described above, is driven by the operator pulling the trigger 12, the rotational force of the motor 20 is transmitted to the support section 43 of the spindle 41 via the reduction mechanism 32, causing the spindle 41 to rotate about its axis. The rotational force of the spindle 41 is transmitted to the hammer 50 via the steel balls 52, the spindle cam grooves 42C, and the hammer cam grooves 50B, so that the hammer 50 rotates in unison with the spindle 41. As the hammer 50 rotates, the anvil 56 rotates together with the hammer 50 due to the engagement between the hammer claws 50E and the anvil claws 56B. This causes the front-end tool 70 to rotate together with the anvil 56, enabling a tightening operation to be performed on a workpiece.

[0053] If the torque required to rotate the front tool 70 during the tightening operation is low, the engagement state of the hammer jaws 50E and anvil jaws 56B is maintained. However, if, for example, towards the end of the tightening operation, the torque required to rotate the front tool 70 increases beyond a predetermined value, the rotation of the front tool 70 and the anvil 56 stops. Since the transmission of drive force from the motor 20 to the spindle 41 via the reduction mechanism 32 continues, the hammer 50 rotates relative to the anvil 56 due to the drive force of the motor 20, thus transferring torque and impact force to the front tool 70.

[0054] Specifically, the steel balls 52 roll in the hammer cam grooves 50B and spindle cam grooves 42C, and the hammer 50 moves backward against the preload force of the hammer spring 54 relative to the spindle 41 and the anvil 56. During this movement, the side surfaces of the hammer claws 50E slide against the side surfaces of the anvil claws 56B, causing the hammer 50 to move backward relative to the anvil 56. When the backward movement of the hammer 50 exceeds the degree of mutual overlap between the hammer claws 50E and the anvil claws 56B, the engagement between the hammer claws 50E and the anvil claws 56B is released.

[0055] After the engagement between the hammer claws 50E and the anvil claws 56B is released, the hammer claws 50E rotate so that they overcome the anvil claws 56B, while, due to the preload force of the hammer spring 54, the hammer 50 is momentarily pushed forward. This causes the hammer claws 50E to engage with the next anvil claw 56B. As a result, the rotational and impact force is transferred from the hammer 50 to the anvil 56. Consequently, a sufficient tightening force can be transferred from the front-end tool 70 to a tightening element such as a screw or the like.

[0056] In this way, the driving force of the motor 20 is transmitted via the spindle 41 to the hammer 50 and the anvil 56 of the impact tool 1, thus transferring rotational and impact forces to the front-end tool 70. The idler wheels 35 of the reduction mechanism 32 are mounted on the spindle 41 in the gear chamber 43A of the support section 43 and are rotatably mounted on the support section 43. The support section 43 has the rear support plate 44 and the front support plate 45, which are arranged opposite each other in the front-to-back direction, with the rear support plate 44 and the front support plate 45 being coupled by the plate coupling sections 46. The plate coupling sections 46 have the corner sections 46C, which are convex towards the spindle shaft 42 when viewed from the front-to-back direction.This creates the possibility that, during operation of the impact tool 1, the force supplied to the spindle 41 (the support section 43) could lead to a stress concentration at the corner sections 46C. If the corner sections 46C are damaged due to this stress concentration, there is a risk of reduced service life for the spindle 41 and the impact tool 1.

[0057] Therefore, the corner sections 46C of the plate coupling sections 46 are chamfered. This prevents stress concentration at the corner sections 46C and simultaneously increases the durability of the impact tool 1. The chamfered hole section 47 is also formed on the support section 43, with its depth direction running front-to-back. Specifically, the chamfered hole section 47 extends from the rear surface of the rear support plate 44 to the rear section of the front support plate 45. Thus, the chamfered hole section 47 runs through the rear support plate 44 and is formed in the rear section of the front support plate 45. Furthermore, when viewed from the front-to-back direction, part of the inner circumferential surface of the chamfered hole section 47 coincides with the corner section 46C.As discussed above, in the third step of the process for manufacturing the spindle 41, the corner section 46C can be chamfered by performing a hole-opening operation (machining) using the drill DR on the support section 43 from the rear side across the entire thickness direction of the plate coupling section 46. Consequently, the machinability of the spindle 41 can be improved. This also increases the durability and machinability of the impact tool 1.

[0058] The chamfer hole section 47 is circular when viewed from the front-to-back direction. Therefore, by performing the hole formation machining using the drill DR as discussed above, the chamfering of the corner sections 46C can be carried out easily. Furthermore, compared to a chamfer hole section 47 with an elongated cut surface, for example, the machining time for the chamfer hole section 47 can be reduced. Consequently, the machining capability of the spindle 41 can be further improved.

[0059] The chamfered hole section 47 is a hole extending in a front-to-back direction through the rear support plate 44 and is designed as a concave blind hole that opens rearward in the front support plate 45. This increases the strength of the support section 43 compared to forming the chamfered hole section 47 continuously through the rear support plate 44 and the front support plate 45.

[0060] The side surfaces of the plate coupling sections 46 are formed by the pair of inclined surfaces 46A, and the R-connection section 46D is formed at a boundary section between the inclined surfaces 46A and the inner circumferential surfaces of the rear support plate 44 and the front support plate 45. In this way, stress concentration at this boundary section can be prevented, while at the same time damage to the plate coupling sections 46 can be effectively prevented. With regard to this point, the description now proceeds by comparison with a [reference to be added]. Fig. Spindle 6, a comparative example, is shown. Fig. Section 6 describes parts formed in the same way as spindle 41 of the present embodiment, provided with the same reference numerals.

[0061] As shown in the view, on the spindle of the comparison example, the chamfer hole section 47 is not formed on the support section 43. Instead, a face mill is inserted into the gear chamber 43C, and the corner sections 46C are machined using the face mill to chamfer the corner sections 46C. Again, the R-approach section 46D is formed by the face milling operation at the boundary section between the corner sections 46C and the inner circumferential surfaces of the rear support plate 44 and front support plate 45. Therefore, a section where the R-approach section 46D of the inclined surfaces 46A and the R-approach section 46D of the corner sections 46C intersect (in Fig. 6 (part shown with arrow C) forms a comparatively acute angle. In the spindle of the comparison example, this easily leads to a stress concentration at this cutting section, so that there is a possibility of damage to the plate coupling sections 46.

[0062] In contrast, as in Fig. As shown in Figure 4, in the present embodiment, the chamfering hole section 47 extends in the front-to-back direction through the plate coupling sections 46 to chamfer the corner sections 46C. Therefore, at the section where the R-approach sections 46D of the inclined surfaces 46A and the corner sections 46C intersect, an acute angle (cutting section) is not formed as described above. According to the present embodiment, the R-approach section 46D can thus be formed at the boundary section between the corner sections 46C and the inner circumferential surfaces of the rear support plate 44 and the front support plate 45, thereby preventing stress concentration at the point where the R-approach section 46D intersects the corner section 46C.Consequently, a stress concentration at the boundary section between the inclined surfaces 46A and the inner circumferential surfaces of the rear support plate 44 and front support plate 45 can be prevented, while at the same time damage to the plate coupling sections 46 can be effectively prevented.

[0063] When viewed from the front-to-back direction, part of the chamfered hole section 47 overlaps with the outer circumferential section of the front shaft section 42B of the spindle shaft 42. Compared to an embodiment in which the chamfered hole section 47 is arranged, for example, radially outward in such a way that it does not overlap with the front shaft section 42B, the cross-sectional area of ​​the plate coupling sections 46 can be increased in this way. This effectively ensures the strength of the plate coupling sections 46.

[0064] The front-end tool 70 is located on the front of the spindle 41, and the front support plate 45 is positioned in front of the rear support plate 44. Since the impact tool 1 transfers torque and impact force to the front-end tool 70, the counterforce acting on the support section 43 during the transfer of torque and impact force to the front-end tool 70 is greater on the front support plate 45 than on the rear support plate 44. Therefore, the thick section 45A is formed on the radially inner part of the front surface of the front support plate 45, with the corner sections 46C superimposing on the thick section 45A when viewed from the front-to-back direction. In other words, a thin section is formed on the radially outer side of the front support plate 45 with respect to the corner sections 46C, and this thin section extends over the entire circumference of the front support plate 45.In this way, the strength of the boundary section between the front support plate 45 and the corner sections 46C, where a stronger counterforce acts, can be ensured at the support section 43, while at the same time a weight reduction of the spindle 41 can be promoted. In other words, damage to the corner sections 46C is effectively prevented, while at the same time a weight reduction of the spindle 41 can be promoted.

[0065] In the present embodiment, in the third step, the chamfer hole section 47 is formed in the support section 43 using the drill DR on the spindle 41; however, the chamfer hole section 47 can also be formed in the support section 43 using a face milling cutter. In this case, as in Fig. Figure 7 shows the bottom surface of the chamfered hole section 47 formed in the front support plate 45, which is flat.

[0066] In the present embodiment, the chamfered hole section 47 is formed as a hole extending in a front-to-back direction through the rear support plate 44 and is designed as a concave blind hole that is open to the rear in the front support plate 45, but, as shown in Fig. As shown in Figure 8, the chamfer hole section 47 can also be formed as a hole section extending through the rear support plate 44 and the front support plate 45. This further improves the machining capability of the spindle 41. In this case, the chamfer hole section 47 is located further outwards in the radial direction compared to the present embodiment.

[0067] In the present embodiment, in the third step of the spindle 41, the chamfered hole section 47 in the support section 43 is formed by machining the support section 43 from the rear with the drill DR. However, the chamfered hole section 47 in the support section 43 can also be formed by machining the support section 43 from the front with the drill DR. In this case, the chamfered hole section 47 is formed as a hole extending through the front support plate 45 and as a blind hole opening forward in the rear support plate 44.

[0068] In the present embodiment, the chamfer hole section 47 is circular when viewed from the front-to-back direction, but the shape of the chamfer hole section 47 is not limited to this shape. Thus, the chamfer hole section 47 can be, as in Fig. 9 shown, also formed as an elongated hole, the longitudinal direction of which is the circumferential direction of the spindle 41. Explanation of reference symbols 1 impact tool (working machine) 20 engine 35 Idler wheel (transmission element) 41 Spindle 42 Spindle shaft (shaft section) 43 Carrier section (preceding section) 44 rear support plate (first wall section) 45 front support plate (second wall section) 45A thick section 46 Plate coupling section (coupling section) 46A inclined surface (side surface) 46D R-approach section 47 chamfer hole section (hole section) 56 Anvil (front end tool holding section) 70 Front-end tool QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2018-86723 A

[0004]

Claims

[1] Working machine, comprising: an engine a spindle that is rotated by the drive of the motor, and a front-end tool holding section that holds a front-end tool and is driven by the rotational force of the spindle, the spindle is designed to include: a wave section a first wall section that extends radially outwards from the wave section, a second wall section that extends radially outwards from the wave section and is arranged opposite the first wall section in the axial direction of the wave section, a coupling section which couples the first wall section and the second wall section together on a radially outer side of the wave section between the first wall section and the second wall section and has a chamfered corner section which is convex towards the side of the wave section when viewed from the axial direction, and a chamfered hole section formed with a depth direction as axial direction from one of the first wall section and the second wall section to the other of the first wall section and the second wall section, and of which part of an inner circumferential surface coincides with the corner section when viewed from the axial direction. [2] Working machine according to claim 1, wherein the chamfer hole section extends through one of the first wall section and the second wall section and the chamfer hole section formed in the other of the first wall section and the second wall section is formed in the form of a depression which opens towards one of the first wall section and the second wall section. [3] Working machine according to claim 1, wherein the chamfering hole section passes through the first wall section and the second wall section. [4] Working machine according to claim 1, wherein the chamfer hole section is circular when viewed from the axial direction. [5] Working machine according to claim 1, wherein the chamfer hole section, when viewed from the axial direction, is formed in the form of an elongated hole, the longitudinal direction of which is the circumferential direction of the spindle. [6] Working machine according to claim 1, wherein the coupling section is designed to include a pair of side surfaces which, when viewed from the axial direction, extend in a direction in which they increasingly approach each other towards the radially inner side of the shaft section, and a corner section which is formed at a part in which the pair of side surfaces intersect each other, wherein an R-approach section is formed at a boundary section between the side surfaces and inner circumferential surfaces of the first wall section and the second wall section. [7] Working machine according to claim 1, wherein, when viewed from the axial direction, a part of the chamfer hole section overlaps with the shaft section. [8] Machine according to claim 1, wherein the front end tool is located on one side of the spindle in the axial direction, the second wall section is arranged on one side of the first wall section in the axial direction, a thick section is provided on the second wall section and the thick section overlaps with the corner section when viewed from the axial direction. [9] Working machine according to one of claims 1 to 8, wherein the coupling section is provided at three locations between the first wall section and the second wall section, the coupling sections being arranged at uniform intervals in the circumferential direction of the shaft section. [10] Working machine according to claim 9, wherein three transmission elements are arranged between the first wall section and the second wall section, which transmit the driving force of the motor, wherein the chamfer hole section is arranged adjacent to the radially inner side of the shaft section when viewed from the axial direction with respect to the corner section, and the transmission elements and the coupling section are arranged alternately in the circumferential direction of the shaft section. [11] Method for manufacturing a spindle for use in a machine tool, wherein the spindle is designed to include: a wave section a first wall section that extends radially outwards from the wave section, a second wall section that extends radially outwards from the wave section and is arranged opposite the first wall section in the axial direction of the wave section, a coupling section which couples the first wall section and the second wall section to each other on the radially outer side of the wave section between the first wall section and the second wall section and has a chamfered corner section, and a chamfered hole section formed with a depth direction as the axial direction on the first wall section and the second wall section, and of which part of an inner circumferential surface coincides with the corner section when viewed from the axial direction, comprising a first step in which the wave section and a projecting section are formed, extending radially outwards from the wave section, a second step in which the protruding section is machined from the radially outer side by means of a face milling cutter, thus forming the first wall section, the second wall section and the coupling section on the protruding section, and a third step in which the protruding section is machined from one side or the other in the axial direction by a drill or a face milling machine, thus forming the chamfered hole section and chamfering the corner section.

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