Magnetic attraction device

Abstract

To provide a magnetic attraction device which can detect presence or absence of a workpiece even when the workpiece has a hole or the workpiece is smaller than a bottom surface of a cylinder tube.SOLUTION: A magnetic attraction device 1 includes: a cylinder tube 7 which has a bottom surface serving as an attraction surface 3 for attracting a workpiece and a pressure chamber 5 inside; a piston 11 which has a permanent magnet 9 and vertically moves in the pressure chamber 5; a control part 13 which makes the attraction surface 3 attract the workpiece W by magnetic force of the permanent magnet 9 by moving the piston 11 to a lower end of the pressure chamber 5 in attracting the workpiece W; and a magnetic sensor 15 which detects a position of the piston 11. The control part 13 moves the piston 11 upward when the workpiece W is not attracted by the attraction surface 3 after the piston 11 is moved to the lower end of the pressure chamber 5, and determines whether or not the workpiece W is attracted by the attraction surface 3 depending on whether or not the magnetic sensor 15 detects upward movement of the piston 11.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a magnetic attraction device. [Background technology]

[0002] Patent Document 1 describes a magnetic chuck that attracts and holds a workpiece by the force of a permanent magnet. In the magnetic chuck of Patent Document 1, when the piston is at the bottom dead center, the attraction surface at the bottom end of the cylinder tube attracts the workpiece. The attracted workpiece is detected by a photoelectric sensor or a proximity sensor provided on the side of the cylinder tube. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-41872 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional magnetic chuck, since a photoelectric sensor is provided on the side surface of the cylinder tube, if there is a hole in the workpiece directly below the sensor where the light hits, the light is not reflected and it is not possible to detect the presence or absence of the workpiece. Similar problems also occur when the workpiece is smaller than the bottom surface of the cylinder tube or when a proximity sensor is provided instead of a photoelectric sensor. [Means for solving the problem]

[0005] One aspect of the present invention is a magnetic adhesion device comprising: a cylinder tube whose bottom surface is an adhesion surface for adsorbing a workpiece and which has an internal pressure chamber; a piston equipped with a permanent magnet and which moves up and down within the pressure chamber; a control unit which, when adsorbing the workpiece, moves the piston to a lower end of the pressure chamber to adsorb the workpiece to the adhesion surface using the magnetic force of the permanent magnet; and a sensor which detects the position of the piston; and if the workpiece is not adsorbed to the adhesion surface after the control unit has moved the piston to the lower end of the pressure chamber, the control unit moves the piston upward and determines whether or not the workpiece is adsorbed to the adhesion surface depending on whether or not the sensor detects that the piston has moved upward.

[0006] According to the magnetic attraction device of one aspect of the present invention, whether or not the workpiece is attracted to the attraction surface is determined based on whether or not the sensor detects that the piston has moved upward. Therefore, even if the workpiece has a hole or is smaller than the bottom surface of the cylinder tube, the presence or absence of the workpiece can be detected. Effect of the Invention

[0007] According to one aspect of the present invention, the presence or absence of a workpiece can be detected even if the workpiece has a hole or is smaller than the bottom surface of the cylinder tube. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing the structure of the magnetic adsorption device according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the structure of the magnetic adsorption device according to the first embodiment. [Figure 3A] FIG. 3A is a perspective view showing the structure of a discharge device including a magnetic adsorption device according to the first embodiment. [Figure 3B] FIG. 3B is a plan view showing the structure of the bottom surface of the discharge device including the magnetic adsorption device according to the first embodiment. [Figure 4]FIG. 4 is a flowchart showing a processing procedure of a workpiece carrying-out process by the carrying-out device equipped with the magnetic attraction device according to the first embodiment. [Diagram 5] FIG. 5 is a diagram for explaining the downward movement of the piston in the magnetic attraction device according to the first embodiment. [Figure 6] FIG. 6 is a diagram for explaining the operation of the magnetic attraction device according to the first embodiment when attracting a workpiece. [Figure 7] FIG. 7 is a diagram for explaining the upward movement of the piston in the magnetic attraction device according to the first embodiment. [Figure 8] FIG. 8 is a diagram for explaining the operation of the magnetic attraction device according to the first embodiment when workpieces are stacked. [Figure 9] FIG. 9 is a cross-sectional view showing the structure of the magnetic adsorption device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [First embodiment] [Magnetic adsorption device] Hereinafter, the magnetic adsorption device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a perspective view showing the structure of the magnetic adsorption device, and FIG. 2 is a cross-sectional view. As shown in FIGS. 1 and 2, the magnetic adsorption device 1 according to the present embodiment includes a cylinder tube 7 having a pressure chamber 5 therein, a piston 11 having a permanent magnet 9 and moving up and down in the pressure chamber 5, a control unit 13 that moves the piston 11 to the lower end of the pressure chamber 5 when adsorbing the workpiece W, and adsorbs the workpiece W to the adsorption surface 3 by the magnetic force of the permanent magnet 9, and a magnetic sensor 15 that detects the position of the piston 11. After moving the piston 11 to the lower end of the pressure chamber 5, if the workpiece W is not adsorbed to the adsorption surface 3, the control unit 13 moves the piston 11 upward, and judges whether the workpiece W is adsorbed to the adsorption surface 3 based on whether the magnetic sensor 15 detects that the piston 11 has moved upward.

[0010] The cylinder tube 7 is made of a paramagnetic metal such as an aluminum alloy, and has a rectangular parallelepiped shape as shown in Fig. 1. As shown in Fig. 2, the bottom surface of the cylinder tube 7 serves as an adsorption surface 3 that adsorbs the workpiece W, and a pressure chamber 5 is provided inside. The pressure chamber 5 has a cylindrical shape, and is separated into an upper space 17 and a lower space 19 by a piston 11 provided inside.

[0011] An upper supply / exhaust hole 21 that communicates with the upper space 17 and supplies / exhausts air, and a lower supply / exhaust hole 23 that communicates with the lower space 19 and supplies / exhausts air, are formed on one side of the cylinder tube 7. The upper supply / exhaust hole 21 is opened when the piston 11 is raised, and air is supplied to the upper supply / exhaust hole 21 when the piston 11 is lowered. The lower supply / exhaust hole 23 is opened when the piston 11 is raised, and air is supplied to the lower supply / exhaust hole 23 when the piston 11 is lowered.

[0012] Furthermore, two mounting grooves 25 (FIG. 1) are formed on the side opposite to the side on which the upper supply / exhaust hole 21 and the lower supply / exhaust hole 23 are formed, and the magnetic sensor 15 is attached to the mounting grooves 25. Since the mounting grooves 25 are formed in the vertical direction, the magnetic sensor 15 can be attached to the side surface of the cylinder tube 7 at a desired position in the vertical direction.

[0013] The piston 11 has a cylindrical shape and is provided with a ferromagnetic core yoke and the like in addition to the permanent magnet 9, and is provided so as to be able to move up and down inside the pressure chamber 5. The piston 11 also has a seal member 27 that contacts the inner surface of the pressure chamber 5, and separates the pressure chamber 5 into an upper space 17 and a lower space 19.

[0014] The magnetic sensor 15 is a sensor that detects the position of the piston 11 by detecting the magnetism of the permanent magnet 9, and when the piston 11 moving inside the cylinder tube 7 approaches and detects the magnetism of the permanent magnet 9, it outputs a detection signal to the control unit 13. As shown in Fig. 2, the magnetic sensor 15 is attached to the upper part of the side surface of the cylinder tube 7, so that when the piston 11 rises, it detects the magnetism of the permanent magnet 9 and outputs a detection signal to the control unit 13. However, the magnetic sensor 15 does not have to be attached to the upper part of the side surface of the cylinder tube 7, and may be attached to the lower side.

[0015] When adsorbing the workpiece W, the control unit 13 executes control to move the piston 11 to the lower end of the pressure chamber 5 and adsorb the workpiece W to the adsorption surface 3 by the magnetic force of the permanent magnet 9. Then, after moving the piston 11 to the lower end of the pressure chamber 5, the control unit 13 determines whether the workpiece W is adsorbed to the adsorption surface 3 based on whether the piston 11 moves upward and the magnetic sensor 15 detects the magnetism of the permanent magnet 9.

[0016] Specifically, the control unit 13 supplies air at a pressure P1 from the upper supply and exhaust hole 21 to the upper space 17, exhausts the air in the lower space 19 from the lower supply and exhaust hole 23 to move the piston 11 to the lower end of the pressure chamber 5, and then supplies air at a predetermined determination pressure P from the lower supply and exhaust hole 23 to the lower space 19, and moves the piston 11 upward when the workpiece W is not adsorbed to the adsorption surface 3. At this time, the determination pressure P is set to be smaller than the pressure that separates the piston 11 adsorbed to the workpiece W from the workpiece W, and larger than the minimum rising pressure that moves the piston 11 not adsorbed to the workpiece W upward.

[0017] That is, when the workpiece W is adhered, the piston 11 will not move upward even if air of the judgment pressure P is supplied, and when the workpiece W is not adhered, the piston 11 moves upward by discharging the air in the upper space 17 from the upper supply and exhaust hole 21 by supplying air of the judgment pressure P. Therefore, if the piston 11 does not move upward and the magnetism of the permanent magnet 9 is not detected by the magnetic sensor 15, it can be determined that the workpiece W is adhered. On the other hand, if the piston 11 moves upward and the magnetism of the permanent magnet 9 is detected by the magnetic sensor 15, it can be determined that the workpiece W is not adhered.

[0018] In this way, after moving the piston 11 to the lower end of the pressure chamber 5, the control unit 13 supplies air at the judgment pressure P and, if the piston 11 does not move upward, determines that the workpiece W is adsorbed to the suction surface 3, and if the piston 11 moves upward, determines that the workpiece W is not adsorbed to the suction surface 3.

[0019] The control unit 13 is configured by a computer having a memory, a processor such as a CPU (Central Processing Unit), and various interfaces. The memory and various interfaces are connected to the processor via a bus. The control unit 13 executes control to determine whether or not the workpiece W is adsorbed to the adsorption surface 3 by executing a program stored in the memory with the processor. The control unit 13 also controls a compressor (not shown) and the like to control the pressure of the air supplied to the pressure chamber 5.

[0020] [Export device] FIG. 3A is a perspective view showing the structure of the unloading device equipped with the magnetic adsorption device according to this embodiment, and FIG. 3B is a plan view showing the structure of the bottom surface of the unloading device. As shown in FIGS. 3A and 3B, the unloading device 31 includes an unloading arm 33, a magnetic adsorption device 1, and a plurality of adsorption pads 35. The unloading device 31 can move in the left-right direction X, the front-back direction Y, and the up-down direction Z by the operation of a driving unit (not shown). In addition, the unloading device 31 can rotate horizontally about a central axis extending in the up-down direction by the operation of the driving unit. Note that, although FIG. 3B shows only one magnetic adsorption device 1, multiple magnetic adsorption devices may be provided. When the workpiece is large or the workpiece is a non-magnetic material, the adsorption pad 35 and the magnetic adsorption device 1 are used in combination to adsorb the workpiece.

[0021] [Work removal processing] Next, a workpiece carrying-out process by the carrying-out device 31 including the magnetic attraction device 1 according to this embodiment will be described. Fig. 4 is a flowchart showing the processing procedure of the workpiece carrying-out process.

[0022] 4, in step S101, the carrying-out device 31 moves to the position of the workpiece W to be carried out and performs positioning. That is, the carrying-out device 31 moves to the position of the X and Y coordinates indicating the position of the workpiece W, and stops at a position directly above the workpiece W.

[0023] In step S103, the unloading device 31 descends from a position directly above the workpiece W to a position where the attraction surface 3 of the magnetic attraction device 1 provided on the unloading device 31 contacts the workpiece W.

[0024] In step S105, the magnetic adsorption device 1 adsorbs the workpiece W. When the discharge device 31 is lowered in step S103, the piston 11 is located at the upper end (top dead center) of the pressure chamber 5. Then, as shown in FIG. 5, the control unit 13 supplies air at pressure P1 from the upper supply and exhaust hole 21 to the upper space 17 and exhausts air from the lower space 19 from the lower supply and exhaust hole 23 to lower the piston 11. The pressure P1 is the pressure required to lower the piston 11. When the piston 11 moves to the lower end (bottom dead center) of the pressure chamber 5, the workpiece W is adsorbed to the adsorption surface 3 by the magnetic force of the permanent magnet 9.

[0025] In step S107, the unloading device 31 slightly rises to check whether the workpiece W is adsorbed on the adsorption surface 3. For example, the unloading device 31 rises by 30 mm.

[0026] In step S109, the control unit 13 supplies air of a determination pressure P for determining whether or not the workpiece W is adsorbed to the adsorption surface 3 in a slightly rising state from the lower supply and exhaust hole 23 to the lower space 19 as shown in FIG. 6. The determination pressure P is set to be smaller than the pressure that separates the piston 11 that is adsorbed to the workpiece W from the workpiece W and larger than the minimum rising pressure that moves the piston 11 that is not adsorbed to the workpiece W upward. In other words, the determination pressure P is a pressure at which the piston 11 does not move if the workpiece W is adsorbed, and the piston 11 moves upward if the workpiece W is not adsorbed. This determination pressure P is set in consideration of the magnetic force of the permanent magnet 9, the weight of the piston 11 and the permanent magnet 9, the sliding resistance when the piston 11 moves, and the like.

[0027] In step S111, the control unit 13 waits for a very short time, for example, 0.4 seconds, and monitors the movement of the piston 11 caused by the supply of air at the determination pressure P.

[0028] In step S113, the control unit 13 determines whether the piston 11 has risen, and if the piston 11 has risen, the process proceeds to step S115, and if the piston 11 has not risen, the process proceeds to step S121. When the workpiece W is not adsorbed, the piston 11 rises due to the air of the determination pressure P as shown in FIG. 7, so that the magnetic sensor 15 detects the magnetic force of the permanent magnet 9 provided on the risen piston 11 and outputs a detection signal. Therefore, when the control unit 13 receives a detection signal from the magnetic sensor 15 after the minute time of step S111 has elapsed, the control unit 13 determines that the piston 11 has risen. On the other hand, when the control unit 13 does not receive a detection signal from the magnetic sensor 15 after the minute time of step S111 has elapsed, the control unit 13 determines that the piston 11 has not risen.

[0029] In step S115, since the workpiece W is not adsorbed to the unloading device 31, the unloading device 31 rises to reattach the workpiece W.

[0030] In step S117, the control unit 13 judges whether the number of retries due to failure to adsorb the workpiece W is the fourth, which is the predetermined number of times. If the number of retries is not the fourth, i.e., if it is the third or less time, the process returns to step S101 to retry adsorbing the workpiece W, and if the number of retries is the fourth time, the process proceeds to step S119. Note that the number of retries does not have to be four, and may be any number other than four.

[0031] In step S119, since the control unit 13 has not been able to adsorb the workpiece W even after retrying three times, it issues an alarm and ends the workpiece carrying-out process according to this embodiment.

[0032] In step S121, the unloading device 31, which has adsorbed the workpiece W, transports the adsorbed workpiece W and moves it to the accumulation position.

[0033] In step S123, the control unit 13 determines whether or not the piston 11 has risen during the transport of the workpiece W, and monitors the state of the piston 11 even during the transport of the workpiece W. If the piston 11 has risen, the process proceeds to step S125, and if the piston 11 has not risen, the process proceeds to step S127.

[0034] In step S125, the control unit 13 determines that the workpiece W has fallen off during transportation, generates an alarm, and ends the workpiece carrying-out process according to this embodiment.

[0035] In step S127, the control unit 13 accumulates the workpieces W at the accumulation position to which the workpieces W have been moved. Specifically, as shown in Fig. 8, the control unit 13 supplies air with a pressure P2 from the lower supply and exhaust hole 23 to the lower space 19 in order to separate the piston 11 adsorbed to the workpieces W from the workpieces W, and exhausts the air in the upper space 17 from the upper supply and exhaust hole 21. This causes the piston 11 to rise, and the workpieces W are separated from the adsorption surface 3 and accumulated.

[0036] In step S129, the control unit 13 waits for a very short time, for example, 0.2 seconds, to confirm that the workpiece W has been reliably released. However, the very short time of 0.2 seconds may be changed.

[0037] In step S131, when the accumulation of the workpieces W is completed, the carrying-out device 31 rises and ends the workpiece carrying-out process according to this embodiment.

[0038] [Effects of the first embodiment] As described above in detail, the magnetic attraction device 1 according to this embodiment moves the piston 11 upward when the workpiece W is not attracted to the attraction surface 3 after the piston 11 is moved to the lower end of the pressure chamber 5, and judges whether the workpiece W is attracted to the attraction surface 3 based on whether the magnetic sensor 15 detects that the piston 11 has moved upward. This makes it possible to detect the presence or absence of the workpiece W even if the workpiece W has a hole or is smaller than the bottom surface of the cylinder tube.

[0039] In addition, the magnetic adsorption device 1 according to this embodiment supplies air at a predetermined determination pressure P to the lower space 19 after moving the piston 11 to the lower end of the pressure chamber 5, and moves the piston 11 upward if the workpiece W is not adsorbed to the adsorption surface 3. The determination pressure P is set to be smaller than the pressure that separates the piston 11 adsorbed to the workpiece W from the workpiece W, and larger than the minimum rising pressure that moves the piston 11 not adsorbed to the workpiece W upward. As a result, if the workpiece W is adsorbed, the piston 11 does not move, and if the workpiece W is not adsorbed, the piston 11 moves upward. Therefore, by supplying air at the determination pressure P, it is possible to determine whether the workpiece W is adsorbed or not.

[0040] Furthermore, the magnetic attraction device 1 according to this embodiment determines that the workpiece W is adsorbed to the attraction surface 3 if the piston 11 does not move upward after moving the piston 11 to the lower end of the pressure chamber 5, and determines that the workpiece W is not adsorbed to the attraction surface 3 if the piston 11 moves upward. As a result, it is possible to determine whether or not the workpiece W is adsorbed based on the movement of the piston 11, and therefore it is possible to detect the presence or absence of the workpiece W even if the workpiece W has a hole or is smaller than the bottom surface of the cylinder tube.

[0041] In addition, the carrying-out device 31 is equipped with the magnetic attraction device 1 according to this embodiment. As a result, the carrying-out device 31 is equipped with the magnetic attraction device 1 that can accurately detect the presence or absence of the workpiece W, so that the carrying-out device 31 can reliably carry out the carrying-out of the workpiece W.

[0042] [Second embodiment] A second embodiment to which the present invention is applied will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals, and detailed description will be omitted. As shown in FIG. 9, the magnetic adsorption device 50 according to this embodiment is different from the first embodiment in that it further includes an elastic member 52. The elastic member 52 is composed of a spring having an elastic force that moves the piston 11 that is not adsorbed to the workpiece W upward, and the elastic force is set to be smaller than the force that separates the piston 11 that is adsorbed to the workpiece W from the workpiece W. In other words, when the workpiece W is adsorbed, the piston 11 does not move, and when the workpiece W is not adsorbed, the piston 11 moves upward due to the elastic force of the elastic member 52. When the piston 11 moves upward, the piston 11 is detected by the magnetic sensor 15 in the same manner as in the first embodiment.

[0043] In the magnetic adsorption device 50 according to this embodiment, in step S105 in FIG. 4, when the workpiece W is adsorbed, air at pressure P1 is supplied from the upper supply and exhaust hole 21 as in the first embodiment, and air is exhausted from the lower supply and exhaust hole 23 to lower the piston 11. Thereafter, in the first embodiment, air at the determination pressure P is supplied in step S109, but in this embodiment, since the elastic member 52 is provided, it is not necessary to supply air at the determination pressure P. That is, in this embodiment, when the control unit 13 stops supplying air at pressure P1, if the workpiece W is not adsorbed to the adsorption surface 3, the piston 11 moves upward due to the elastic force of the elastic member 52. Therefore, in the magnetic adsorption device 50 according to this embodiment, if step S109 in FIG. 4 is deleted, the workpiece unloading process can be executed.

[0044] [Effects of the second embodiment] As described above in detail, the magnetic adsorption device 50 according to this embodiment further includes the elastic member 52 having an elastic force that moves the piston 11 upward when the workpiece W is not adsorbed. The elastic force is set to be smaller than the force that separates the piston 11, which is adsorbed to the workpiece W, from the workpiece W. When the workpiece W is not adsorbed to the adsorption surface 3 after the control unit 13 moves the piston 11 to the lower end of the pressure chamber 5, the elastic member 52 moves the piston 11 upward by the elastic force. As a result, if the workpiece W is adsorbed, the piston 11 does not move, and if the workpiece W is not adsorbed, the piston 11 moves upward. Therefore, it is possible to determine whether the workpiece W is adsorbed or not by the movement of the piston 11 caused by the elastic member 52.

[0045] As described above, the embodiment of the present invention has been described, but the description and drawings forming a part of this disclosure should not be understood as limiting this invention. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art. [Explanation of symbols]

[0046] 1, 50 Magnetic adsorption device 3 Adsorption surface 5. Pressure Chamber 7 Cylinder tube 9. Permanent Magnets 11 Piston 13 Control section 15 Magnetic Sensor 17 Upper space 19 Lower space 21 Upper ventilation hole 23 Lower exhaust port 25 Mounting groove 27 Sealing material 31 Unloading device 33 Ejection arm 35 Suction Pad 52 Elastic member P, P1, P2 pressure Double work

Claims

1. A cylinder tube with a pressure chamber inside and a bottom surface that is an adsorption surface for adsorbing a workpiece; A piston having a permanent magnet and moving up and down within the pressure chamber; a control unit that moves the piston to a lower end of the pressure chamber when the workpiece is attracted to the attraction surface by the magnetic force of the permanent magnet; a sensor for detecting a position of the piston; When the workpiece is not adsorbed to the adsorption surface after the piston is moved to the lower end of the pressure chamber, the control unit moves the piston upward, and determines whether the workpiece is adsorbed to the adsorption surface based on whether the sensor detects that the piston has moved upward. Magnetic adsorption device.

2. The piston separates the pressure chamber into an upper space and a lower space, the control unit supplies air at a predetermined determination pressure to the lower space after moving the piston to the lower end of the pressure chamber, and moves the piston upward when the workpiece is not adsorbed to the adsorption surface; The judgment pressure is set to be smaller than the pressure that separates the piston, which is attached to the workpiece, from the workpiece and larger than the minimum rising pressure that moves the piston, which is not attached to the workpiece, upward. The magnetic adsorption device according to claim 1 .

3. The piston further includes an elastic member having an elastic force that moves the piston upward when the piston is not attached to the workpiece, the elastic force is set to be smaller than a force that separates the piston, which is attached to the workpiece, from the workpiece; When the workpiece is not attracted to the attraction surface after the control unit has moved the piston to the lower end of the pressure chamber, the elastic member causes the piston to move upward by the elastic force. The magnetic adsorption device according to claim 1 .

4. The control unit determines that the workpiece is adhered to the adsorption surface when the piston does not move upward after moving the piston to the lower end of the pressure chamber, and determines that the workpiece is not adhered to the adsorption surface when the piston moves upward. The magnetic adsorption device according to any one of claims 1 to 3.

5. A discharge device comprising the magnetic adsorption device according to any one of claims 1 to 3.

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