Magnetic chuck

Abstract

A magnetic chuck is provided. The magnetic chuck (10) includes a cylinder (12) having a workpiece chucking surface (12c) that chucks a workpiece (W), a piston assembly (14) that includes a permanent magnet (42) and is movable within an internal space (25) of the cylinder, dividing the internal space of the cylinder into a first pressure chamber (112) and a second pressure chamber (114), a first supply / discharge port (26) formed in the cylinder and communicating with the first pressure chamber, a second supply / discharge port (76) formed in the cylinder and communicating with the second pressure chamber, and a communication passage (71) that communicates the first pressure chamber and the second pressure chamber.

Description

Technical Field

[0001] This invention relates to magnetic chucks. Background Technology

[0002] A known magnetic chuck connects a permanent magnet to a piston inside a cylinder, causing the permanent magnet and piston to move together (see Japanese Utility Model Application Publication No. 51-102174). In such a magnetic chuck, the permanent magnet approaches the workpiece following the displacement of the piston, which is subjected to fluid pressure. As the permanent magnet approaches the workpiece, the workpiece is attracted and held. Furthermore, if the piston moves away from the workpiece, the workpiece is released. Summary of the Invention

[0003] When adsorbing and maintaining a workpiece at a high temperature, damage to the components housed within the magnetic chuck is a concern. Ideally, damage to the components of the magnetic chuck should also be suppressed when adsorbing and maintaining a workpiece at a high temperature.

[0004] The purpose of this invention is to provide a magnetic chuck with good heat resistance.

[0005] One aspect of the magnetic chuck of the present invention comprises: a cylinder having a workpiece adsorption surface for adsorbing workpieces; a piston assembly including a permanent magnet and movable within the internal space of the cylinder, dividing the internal space of the cylinder into a first pressure chamber and a second pressure chamber; a first discharge port formed in the cylinder and communicating with the first pressure chamber; a second discharge port formed in the cylinder and communicating with the second pressure chamber; and a connecting passage connecting the first pressure chamber and the second pressure chamber.

[0006] According to the present invention, a magnetic chuck with good heat resistance can be provided.

[0007] The above-described objectives, features, and advantages can be readily understood from the following description of embodiments illustrated with reference to the accompanying drawings. Attached Figure Description

[0008] Figure 1 This is a front view showing the magnetic chuck of the first embodiment.

[0009] Figure 2 This is a cross-sectional view showing the magnetic chuck of the first embodiment.

[0010] Figure 3 This is a cross-sectional view showing the magnetic chuck of the first embodiment.

[0011] Figure 4 This is an exploded perspective view of the magnetic chuck of the first embodiment.

[0012] Figure 5This is a cross-sectional view showing the magnetic chuck of the second embodiment.

[0013] Figure 6 This is a cross-sectional view showing the magnetic chuck of the second embodiment.

[0014] Figure 7 This is a cross-sectional view showing the magnetic chuck of the third embodiment.

[0015] Figure 8 This is a cross-sectional view showing the magnetic chuck of the third embodiment.

[0016] Figure 9 This is a rear view showing the magnetic chuck of the fourth embodiment.

[0017] Figure 10 This is a cross-sectional view showing the magnetic chuck of the fourth embodiment.

[0018] Figure 11 This is a cross-sectional view showing the magnetic chuck of the fourth embodiment.

[0019] Figure 12 This is a cross-sectional view showing a portion of the magnetic chuck in a modified example of the fourth embodiment.

[0020] Figure 13 This is a block diagram showing a modified example of the fourth embodiment of the magnetic chuck. Detailed Implementation

[0021] The magnetic chuck of the present invention is described in detail below with reference to the accompanying drawings, as follows: Preferred embodiments are listed.

[0022] [First Implementation Method]

[0023] use Figures 1-4 The magnetic chuck of the first embodiment will be described. Figure 1 This is a front view showing the magnetic chuck of this embodiment. Figure 2 and Figure 3 This is a cross-sectional view showing the magnetic chuck of this embodiment. Figure 2 The text indicates that the piston assembly 14 is at top dead center. Figure 3 The text indicates that the piston assembly 14 is at bottom dead center. Additionally, in... Figure 3 The text indicates that the workpiece W is attracted to the magnetic chuck 10. Figure 4 This is an exploded perspective view showing the magnetic chuck of this embodiment. Furthermore, in this application specification, the magnetic chuck 10... Figure 1 The surface on the upper side of the paper is called the top surface, and the magnetic chuck 10 is placed on it. Figure 1 The surface below the paper is called the lower surface. The workpiece W is attracted to the lower surface of the magnetic chuck 10.

[0024] like Figure 2 and Figure 3 As shown, the magnetic chuck 10 of this embodiment includes a cylinder 12, a piston assembly 14, a base cover 18, and a latching yoke 20. The magnetic chuck 10 is, for example, mounted on the top arm of a robot (not shown).

[0025] A cylinder bore 24 is formed in the cylinder barrel 12. The cylinder bore 24 extends through the cylinder barrel 12. The cross-sectional shape of the cylinder bore 24 is, for example, circular. That is, the cross-sectional shape of the cylinder bore 24 in the direction perpendicular to the central axis C of the cylinder barrel 12 is, for example, circular. The central axis of the cylinder bore 24 coincides with the central axis C of the cylinder barrel 12. The cylinder barrel 12 is made of paramagnetic metals such as aluminum alloy, but is not limited thereto.

[0026] like Figure 1 As shown, the cylinder 12 includes a first end 12d and a second end 12e. The first end 12d and the second end 12e are located in opposite positions to each other. The first end 12d includes a workpiece adsorption surface 12c for adsorbing the workpiece W. Figure 2 and Figure 3 As shown, a fitting portion 22 is formed at the first end 12d of the cylinder 12 to fit into the outer casing 86 described later. The cross-sectional shape of the portion of the cylinder 12 other than the fitting portion 22 is, for example, rectangular. The cross-sectional shape of the fitting portion 22 in the cylinder 12 is, for example, circular.

[0027] A stepped portion 23 is formed at the top of the fitting portion 22 in the cylinder barrel 12 for mounting the second seal 96, which will be described later. In addition, a stepped portion 32 is formed on the upper side of the cylinder bore 24, which engages with the flange 20a formed on the latch yoke 20, which will be described later.

[0028] The piston assembly 14 includes a seal holder 38, a magnetic core yoke 40, a permanent magnet 42, a cover yoke 44, and an annular plate 45.

[0029] The seal holder 38 is formed in a disc shape. The material of the seal holder 38 may be a paramagnetic metal such as aluminum alloy, but is not limited thereto. A groove 39 is formed on the outer periphery of the seal holder 38. The groove 39 opens outward in the circumferential direction of the seal holder 38. A piston seal 46 is installed in the groove 39. The material of the piston seal 46 may be fluororubber, but is not limited thereto. The piston seal 46 slides in contact with the wall of the cylinder bore 24. A through hole 48 is formed in the center of the seal holder 38. An inwardly projecting flange 50 protruding toward the center of the through hole 48 is formed in the through hole 48. An annular recess 51 is formed on the upper surface of the seal holder 38. The annular recess 51 opens toward the upper surface of the magnetic chuck 10. The portion between the through hole 48 and the annular recess 51 is a flange 41. The flange 41 protrudes toward the upper surface of the magnetic chuck 10.

[0030] The magnetic core yoke 40 is generally cylindrical. The material used for the magnetic core yoke 40 may include, for example, steel, a strong magnetic material, but is not limited to this. A cylindrical protrusion 52 is formed at the center of the upper end of the magnetic core yoke 40. The cylindrical protrusion 52 protrudes towards the upper surface of the magnetic chuck 10. A bottomed threaded hole 54 is formed in the magnetic core yoke 40. The threaded hole 54 opens at the top of the cylindrical protrusion 52. A recess 56 is formed on the lower side of the magnetic core yoke 40. The recess 56 opens towards the lower surface of the magnetic chuck 10. The cross-sectional shape of the recess 56 is, for example, circular.

[0031] A cylindrical protrusion 52 is inserted into the through hole 48 formed in the seal holder 38. The cylindrical protrusion 52 is inserted into the lower part of the through hole 48. The cylindrical protrusion 52 engages with the through hole 48. The cylindrical protrusion 52 abuts against the inward flange 50 in the seal holder 38. A fixing screw 60 is inserted into the through hole 48. The fixing screw 60 is inserted from the upper part of the through hole 48. The fixing screw 60 is further inserted into the threaded hole 54 formed in the magnetic core yoke 40. The fixing screw 60 engages with the threaded hole 54. In this way, the seal holder 38 and the magnetic core yoke 40 are integrally connected.

[0032] A first seal 62 is installed at the root of the cylindrical protrusion 52. The first seal 62 seals the space between the seal holder 38 and the magnetic core yoke 40. The material of the first seal 62 may be, for example, fluororubber, but is not limited thereto.

[0033] The permanent magnet 42 is formed, for example, in a cylindrical shape. The permanent magnet 42 is located on the outer periphery of the magnetic core yoke 40. For example, a samarium cobalt magnet is used as the permanent magnet 42, but it is not limited to this. The permanent magnet 42 is surrounded by a sealing retainer 38, a magnetic core yoke 40, a cover yoke 44, and an annular plate 45. The permanent magnet 42 is magnetized, for example, radially. The inner circumferential side of the permanent magnet 42 is, for example, an N pole, and the outer circumferential side is, for example, an S pole. Alternatively, the inner circumferential side of the permanent magnet 42 may be an S pole, and the outer circumferential side may be an N pole. The permanent magnet 42 is, for example, divided circumferentially. That is, a cylindrical permanent magnet 42 is constructed by combining multiple fan-shaped (not shown) magnet pieces. Alternatively, the permanent magnet 42 may be constructed from a single component. The permanent magnet 42 is not limited to a cylindrical shape. For example, the permanent magnet 42 may also be formed in a square tube shape. That is, a cylindrical permanent magnet 42 can also be formed by combining multiple flat magnetic sheets.

[0034] The cover yoke 44 is formed in a cylindrical shape. The cover yoke 44 is located on the outer periphery of the permanent magnet 42. The material of the cover yoke 44 can be, for example, steel, a strongly magnetic material, but is not limited to this. The upper part of the outer periphery of the cover yoke 44 has a large diameter, and the lower part has a small diameter. That is, the cover yoke 44 includes a large diameter portion 64 and a small diameter portion 66. A step portion 65 exists between the large diameter portion 64 and the small diameter portion 66. Two annular grooves 68a and 68b are formed in the large diameter portion 64. The annular grooves 68a and 68b open radially outward toward the cover yoke 44. The annular grooves 68a and 68b are separated from each other in the direction along the central axis C of the cylinder 12. Wear rings 70a and 70b are respectively installed in the annular grooves 68a and 68b. The piston assembly 14 is guided and supported in the cylinder bore 24 via the wear rings 70a and 70b. For example, polytetrafluoroethylene (PTFE) can be used as the material for wear rings 70a and 70b. However, the materials used for wear rings 70a and 70b are not limited to such materials.

[0035] The bottom cover 18 includes a bottom magnetic yoke 80, an outer magnetic yoke 82, and a housing 86.

[0036] The material for the bottom yoke 80 may be, for example, steel, a strong magnetic material, but is not limited to this. The shape of the bottom yoke 80 may be, for example, cylindrical. When the piston assembly 14 descends, the bottom yoke 80 enters the recess 56 of the core yoke 40 (see reference). Figure 3 A lower flange 80a is formed at the lower part of the bottom yoke 80. The lower flange 80a protrudes radially outward from the bottom yoke 80.

[0037] An outer magnetic yoke 82 is provided on the outer side of the bottom magnetic yoke 80. The material of the outer magnetic yoke 82 may be, for example, steel, a strongly magnetic material, but is not limited to this. The outer magnetic yoke 82 is formed, for example, in a cylindrical shape. An upper flange 82a is formed on the upper side of the outer magnetic yoke 82. The upper flange 82a protrudes radially outward from the outer magnetic yoke 82. An outer peripheral recess 82b is formed on the outer peripheral surface of the lower side of the outer magnetic yoke 82. The outer peripheral recess 82b is recessed radially inward from the outer magnetic yoke 82. A stepped portion 82c is formed on the inner peripheral surface of the lower side of the outer magnetic yoke 82.

[0038] An annular connecting plate 84 is provided between the lower flange 80a of the bottom yoke 80 and the stepped portion 82c of the outer yoke 82. The outer yoke 82 is fixed to the bottom yoke 80 by the connecting plate 84. The connecting plate 84 is made of paramagnetic metals such as aluminum alloy, but is not limited to this.

[0039] The outer casing 86 is formed in a cylindrical shape, for example. The material of the outer casing 86 may be a paramagnetic metal such as aluminum alloy, but is not limited to this. A through hole 88 extending vertically is formed in the outer casing 86. The cross-section of the through hole 88 is circular. A lower flange 90 is formed on the lower side of the through hole 88. The lower flange 90 protrudes radially inward from the through hole 88. The fitting portion 22 of the cylinder 12 engages with the through hole 88 of the outer casing 86.

[0040] like Figure 4 As shown, four through bolts 94 are inserted into the through holes 35 formed in the outer casing 86. The top end of each through bolt 94 engages with a threaded hole (not shown) formed in the cylinder 12. In this way, the cylinder 12 and the outer casing 86 are connected and fixed to each other. The upper flange 82a of the outer magnetic yoke 82 is clamped between the end face of the fitting portion 22 of the cylinder 12 and the lower flange 90 of the outer casing 86. In this way, the outer magnetic yoke 82 is connected and fixed to the cylinder 12, etc.

[0041] As described above, a stepped portion 23 is formed at the top of the fitting portion 22 of the cylinder 12. A second seal 96 is installed in the gap between the stepped portion 23 and the upper surface of the outer magnetic yoke 82. The second seal 96 seals the cylinder 12 and the outer magnetic yoke 82. The material of the second seal 96 is, for example, fluororubber, but is not limited thereto.

[0042] A shock absorber (lower shock absorber 98) is installed between the lower end of the cylinder 12 and the upper surface of the outer magnetic yoke 82. The lower shock absorber 98 is formed in an annular shape. The material used for the lower shock absorber 98 may be, for example, fluororubber, but is not limited to this. The upper surface of the lower shock absorber 98 faces the annular recess 30 formed in the cylinder 12. When the piston assembly 14 descends to the bottom dead center, as... Figure 3 As shown, the stepped portion 65 of the magnetic yoke 44 abuts against the lower shock absorber 98. The lower shock absorber 98 serves to mitigate the impact generated when the piston assembly 14 moves within the internal space 25. That is, the lower shock absorber 98 serves to mitigate the impact when the piston assembly 14 descends to the bottom dead center. Figure 4As shown, a plurality of grooves 98a (recesses) are formed on the upper surface of the lower shock absorber 98, extending from the inner circumferential end of the lower shock absorber 98 to the outer circumferential end of the lower shock absorber 98. The grooves 98a are formed, for example, at equal intervals in the circumferential direction of the lower shock absorber 98. The grooves 98a serve to connect the first fluid supply / discharge port 28 (described later) to the cylinder bore 24. That is, the grooves 98a serve to connect the first supply / discharge port 26 (described later) to the first pressure chamber 112 (described later). When the piston assembly 14 is at bottom dead center, the first fluid supply / discharge port 28 also connects to the cylinder bore 24 via the grooves 98a. The grooves 98a also serve to connect the second connecting hole 74b (described later) to the cylinder bore 24. That is, the grooves 98a also serve to connect the first connecting passage 71A (described later) to the first pressure chamber 112.

[0043] The workpiece W is attracted to the lower surface of the magnetic chuck 10. Examples of workpiece W include, but are not limited to, iron plates.

[0044] The latching yoke 20 is formed in a disk shape. The material used for the latching yoke 20 may include, for example, steel, a strong magnetic material, but is not limited to this. A flange 20a is formed on the upper side of the latching yoke 20. The flange 20a protrudes radially outward from the latching yoke 20. The flange 20a engages with a stepped portion 32 formed on the upper side of the cylinder bore 24. A recess 102 is formed in the center of the latching yoke 20. The recess 102 opens toward the lower surface of the magnetic chuck 10. The cross-section of the recess 102 is, for example, circular. The recess 102 includes a small-diameter portion 102a and a large-diameter portion 102b. The small-diameter portion 102a is located on the upper side of the recess 102. The large-diameter portion 102b is located on the lower side of the recess 102. When the piston assembly 14 is raised, the head 60a of the retaining screw 60 is accommodated within the small-diameter portion 102a (see reference). Figure 2 An upper shock absorber 104 is installed in the large-diameter section 102b. The upper shock absorber 104 is formed in a ring shape. When the piston assembly 14 rises, as... Figure 2As shown, the flange 41 in the seal holder 38 abuts against the upper shock absorber 104. The upper shock absorber 104 serves to mitigate the impact when the piston assembly 14 rises. The upper shock absorber 104 is made of materials such as fluororubber, but is not limited to these. An annular protrusion 106 is formed at the lower end of the large-diameter portion 102b. The inner diameter of the annular protrusion 106 tapers downwards. When the piston assembly 14 rises, the annular protrusion 106 enters the annular recess 51 formed in the seal holder 38. A groove 21 is formed on the outer periphery of the latch yoke 20. The groove 21 opens radially outwards from the latch yoke 20. A latch yoke seal 27 is installed in the groove 21. The latch yoke seal 27 is made of materials such as fluororubber, but is not limited to these. A small-diameter portion 20b is formed on the lower side of the latch yoke 20. There is a gap 114a between the outer peripheral surface of the small diameter portion 20b in the latching yoke 20 and the wall surface of the cylinder bore 24. The gap 114a is part of the second pressure chamber 114, which will be described later.

[0045] A groove 12b is formed on the upper side of the cylinder 12. The groove 12b opens toward the central axis C of the cylinder 12. A retaining ring 16 is fitted into the groove 12b. The retaining ring 16 is an annular retaining ring used to prevent the latching yoke 20 from falling off in the axial direction of the cylinder 12. The axial direction of the cylinder 12 is along the central axis C. The retaining ring 16 can be made of, for example, spring steel, but is not limited to this.

[0046] The internal space 25 of the cylinder 12 is divided by the piston assembly 14 into a first pressure chamber 112 and a second pressure chamber 114. The first pressure chamber 112 is the pressure chamber located below the piston seal 46 relative to the seal holder 38. The second pressure chamber 114 is the pressure chamber located above the piston seal 46 relative to the seal holder 38. The first pressure chamber 112 is located between the second pressure chamber 114 and the workpiece adsorption surface 12c.

[0047] A first feed port 26 for supplying or discharging fluid into the first pressure chamber 112 is formed in the cylinder 12. The cylinder 12 includes a first side portion 12f and a second side portion 12g. The first side portion 12f and the second side portion 12g are located opposite each other with respect to the central axis C of the cylinder 12. The first feed port 26 is provided on the first side portion 12f of the cylinder 12. The cylinder 12 has a first side surface 13A and a second side surface 13B. The first side surface 13A and the second side surface 13B are located opposite each other. The first feed port 26 opens on the first side surface 13A of the cylinder 12. As the fluid, a gas such as air is used, but it is not limited to this. Liquids such as water and oil can also be used as the fluid. The temperature of the fluid is, for example, room temperature (around 25°C), but it is not limited to this. However, in order to adequately cool the magnetic chuck 10, it is preferable that the temperature of the fluid is sufficiently low relative to the temperature of the workpiece W.

[0048] A first fluid supply / discharge port 28 is formed inside the wall 12a of the cylinder 12. A first supply / discharge port 26 is connected to the upper end of the first fluid supply / discharge port 28. The first fluid supply / discharge port 28 extends axially along the cylinder 12 inside the wall 12a of the cylinder 12. An annular recess 30 is formed on the inner circumferential side of the fitting portion 22, opening toward the lower surface of the magnetic chuck 10. The lower end of the first fluid supply / discharge port 28 reaches the annular recess 30. The first supply / discharge port 26 communicates with the first pressure chamber 112 via the first fluid supply / discharge port 28. The first fluid supply / discharge port 28 has an opening 81b communicating with the first pressure chamber 112. The opening 81b communicating with the first pressure chamber 112 is provided on the first side portion 12f of the cylinder 12.

[0049] The cylinder 12 is provided with a second feed port 76 for supplying and discharging fluid into the second pressure chamber 114. Similar to the first feed port 26, the second feed port 76 is located on the first side portion 12f of the cylinder 12. The second feed port 76 opens on the first side surface 13A of the cylinder 12. The second feed port 76 is located above the first feed port 26.

[0050] A second fluid supply / discharge port 110 is formed inside the wall 12a of the cylinder 12. One end of the second fluid supply / discharge port 110 is connected to a second supply / discharge port 76. The second fluid supply / discharge port 110 extends inside the wall 12a of the cylinder 12 toward the cylinder bore 24. A gap 114a formed between the outer peripheral surface of the small-diameter portion 20b in the latch yoke 20 and the wall surface of the cylinder bore 24 communicates with the other end of the second fluid supply / discharge port 110. As described above, this gap 114a is part of the second pressure chamber 114. The second supply / discharge port 76 communicates with the second pressure chamber 114 via the second fluid supply / discharge port 110. The second fluid supply / discharge port 110 has an opening 81a communicating with the second pressure chamber 114. The opening 81a communicating with the second pressure chamber 114 is provided on the first side portion 12f of the cylinder 12.

[0051] A connecting passage 71 is formed in the cylinder 12, connecting the first pressure chamber 112 and the second pressure chamber 114. The connecting passage 71 includes a first connecting passage 71A. The first connecting passage 71A is formed inside the wall 12a of the cylinder 12. The first connecting passage 71A is formed independently of the internal space 25 of the cylinder 12. The first connecting passage 71A is disposed on the second side portion 12g of the cylinder 12. As described above, the first side portion 12f and the second side portion 12g are located in opposite positions relative to each other with reference to the central axis C of the cylinder 12. The first side portion 12f of the cylinder 12 has a first feed port 26 and a second feed port 76, and the second side portion 12g of the cylinder 12 has the first connecting passage 71A. The first feed port 26 and the second feed port 76 are disposed on the first side portion 12f of the cylinder 12, and the connecting passage 71 is disposed on the second side portion 12g of the cylinder 12 for the following reasons. That is, this is to suppress the stagnation of fluid in the first pressure chamber 112 and the second pressure chamber 114, so as to effectively cool the various parts of the magnetic chuck 10 through the fluid.

[0052] In the first connecting passage 71A, a flow regulating valve 72, more specifically a needle valve, is provided for adjusting the flow rate of the fluid flowing in the first connecting passage 71A. As described above, the second end 12e of the cylinder 12 is located opposite to the first end 12d, which includes the workpiece adsorption surface 12c. The flow regulating valve 72 is provided at the second end 12e. The flow regulating valve 72 is mounted in a recess 73 formed in the cylinder 12. The recess 73 opens radially outward toward the cylinder 12. The recess 73 opens at the second side surface 13B of the cylinder 12. The depth direction of the recess 73 is radial to the cylinder 12. The cross-section of the axial recess 73 of the cylinder 12 is, for example, circular. A stepped portion 73a is formed in the recess 73 for mounting a seal 75, described later. A seal 75 is installed in the gap between the stepped portion 73a and the flow regulating valve 72. The seal 75 seals the cylinder 12 and the flow regulating valve 72. The material used for the seal 75 may be, for example, fluororubber, but is not limited to this.

[0053] The first connecting passage 71A includes a first connecting hole 74a and a second connecting hole 74b. A gap 114a formed between the outer peripheral surface of the small-diameter portion 20b in the latch yoke 20 and the wall surface of the cylinder bore 24 communicates with one end of the first connecting hole 74a. The first connecting hole 74a, i.e., the connecting hole, has an opening 79a communicating with the second pressure chamber 114. The opening 79a communicating with the second pressure chamber 114 is located on the second side portion 12g of the cylinder 12. The other end of the first connecting hole 74a opens on the bottom surface of the recess 73. The central axis of the first connecting hole 74a coincides with the central axis of the flow regulating valve 72. The upper end of the second connecting hole 74b opens on the side surface of the recess 73. The second connecting hole 74b extends downwards from the interior of the wall 12a of the cylinder 12. The lower end of the second connecting hole 74b reaches the annular recess 30 formed in the cylinder 12. The first connecting passage 71A communicates with the first pressure chamber 112 via a groove 98a formed in the lower shock absorber 98. That is, the second connecting hole 74b has an opening 79b communicating with the first pressure chamber 112. The opening 79b communicating with the first pressure chamber 112 is provided on the second side portion 12g of the cylinder 12.

[0054] The flow regulating valve 72 includes a main body 72a and a core 72b. The main body 72a is generally cylindrical. The core 72b is generally cylindrical. The core 72b is surrounded by the main body 72a. The core 72b has a large-diameter portion 72b1 and a small-diameter portion 72b2. The small-diameter portion 72b2 is located at the top of the core 72b. The small-diameter portion 72b2, i.e., the top of the core 72b, is inserted into a first connecting hole 74a. If the core 72b is rotated, it will displace along its length. If the core 72b is displaced along its length, the size of the gap between the first connecting passage 71A and the core 72b changes, thereby adjusting the flow rate of the fluid in the first connecting passage 71A. To generate a sufficient differential pressure between the first pressure chamber 112 and the second pressure chamber 114 when driving the piston assembly 14, the clearance between the first connecting passage 71A and the mandrel 72b is set to be sufficiently small. An annular groove 72b3 is formed in the mandrel 72b. The annular groove 72b3 opens radially outward toward the mandrel 72b. A seal 77 is installed in the annular groove 72b3. The seal 77 seals the space between the main body 72a and the mandrel 72b. The material used for the seal 77 may be, for example, fluororubber, but is not limited to this.

[0055] The first feed port 26 and the first connecting passage 71A are connected via the first pressure chamber 112. When the piston assembly 14 is at bottom dead center, as... Figure 3 As shown, the first supply / discharge port 26 and the first connecting passage 71A are also maintained in a state where they are connected via the first pressure chamber 112.

[0056] The second feed port 76 is connected to the first connecting passage 71A via the second pressure chamber 114. When the piston assembly 14 is at top dead center, as... Figure 2 As shown, the second supply / discharge port 76 is also maintained in a state where the first connecting passage 71A is connected to the second pressure chamber 114.

[0057] Thus, the magnetic chuck 10 constitutes this embodiment.

[0058] Next, use Figure 2 and Figure 3 The operation of the magnetic chuck 10 in this embodiment will be explained. Figure 2 The state shown, i.e., the state in which the piston assembly 14 is at the top dead center (rising end), is set as the initial state.

[0059] When the piston assembly 14 is at top dead center, the piston assembly 14, which includes the permanent magnet 42, is attracted by the latching yoke 20 with a predetermined magnetic attraction.

[0060] Before the magnetic chuck 10 is used, such as during transport, the piston assembly 14 can be held at the top dead center position by the action of the latching yoke 20 even without supplying fluid to the magnetic chuck 10. This prevents accidental situations such as the magnetic chuck 10 attracting surrounding ferrous materials, ensuring safety.

[0061] Next, while maintaining the magnetic chuck 10 in its initial state, a robot (not shown) is driven to bring the magnetic chuck 10 into contact with the workpiece W. More specifically, the lower surface of the magnetic chuck 10 is brought into contact with the workpiece W.

[0062] Next, fluid is supplied to the second pressure chamber 114 and discharged from the first pressure chamber 112 by operating a switching valve (not shown). The supply of fluid to the second pressure chamber 114 is performed via the second supply / discharge port 76. The discharge of fluid from the first pressure chamber 112 is performed via the first supply / discharge port 26.

[0063] If fluid is supplied to the second pressure chamber 114 and fluid begins to be discharged from the first pressure chamber 112, a pressure differential is created between the first pressure chamber 112 and the second pressure chamber 114. Therefore, the force required to drive the piston assembly 14 downwards acts on the piston assembly 14 in accordance with the pressure differential between the first pressure chamber 112 and the second pressure chamber 114. The piston assembly 14 is held at top dead center during the phase where the force required to drive the piston assembly 14 downwards does not exceed the magnetic attraction force acting between the latch yoke 20 and the piston assembly 14. As described above, since the clearance between the mandrel 72b of the flow regulating valve 72 and the first communication channel 71A is set sufficiently small, the pressure in the second pressure chamber 114 is sufficiently high relative to the pressure in the first pressure chamber 112. If the force required to drive the piston assembly 14 downwards exceeds the magnetic attraction force acting between the latch yoke 20 and the piston assembly 14, the piston assembly 14 begins to descend.

[0064] As the piston assembly 14 descends, the magnetic attraction between the latching yoke 20 and the piston assembly 14 gradually decreases. On the other hand, the magnetic attraction between the bottom yoke 80 and the piston assembly 14, and the magnetic attraction between the outer yoke 82 and the piston assembly 14, gradually increase.

[0065] If the piston assembly 14 descends further, the bottom yoke 80 enters the recess 56 of the core yoke 40. Then, the stepped portion 65 of the cover yoke 44 abuts against the lower damper 98, and the piston assembly 14 reaches the bottom dead center (descending end). When the piston assembly 14 is at the bottom dead center, the magnetic flux density through the workpiece W is at its maximum, and the workpiece W is attracted and held by the magnetic chuck 10 with the maximum magnetic attraction.

[0066] The workpiece W is sometimes at room temperature, but sometimes at high temperature. When the workpiece W is attracted and held by the magnetic chuck 10, the heat of the workpiece W is transferred to the magnetic chuck 10. Materials used for the first seal 62, the second seal 96, the piston seal 46, the lower shock absorber 98, etc., such as fluororubber, may not be able to withstand significantly high temperatures. When the first seal 62, the second seal 96, the piston seal 46, the lower shock absorber 98, etc., are at significantly high temperatures, damage may be caused to the first seal 62, the second seal 96, the piston seal 46, the lower shock absorber 98, etc. In contrast, in this embodiment, since the first pressure chamber 112 and the second pressure chamber 114 are connected via the connecting passage 71 (first connecting passage 71A), fluid continues to flow in the first pressure chamber 112 even when the piston assembly 14 is at the bottom dead center. Therefore, according to this embodiment, the magnetic chuck 10 can be cooled by a fluid, which can suppress damage to the first seal 62, the second seal 96, the piston seal 46, the lower shock absorber 98, etc.

[0067] With the piston assembly 14 at bottom dead center, the workpiece W is conveyed to a predetermined position. That is, with the magnetic chuck 10 holding the workpiece W, the workpiece W is conveyed to the predetermined position. Then, an operation is performed to release the workpiece W from the magnetic chuck 10. This operation is performed by operating a switching valve (not shown). Specifically, fluid is supplied to the first pressure chamber 112 and fluid is discharged from the second pressure chamber 114. While fluid is supplied to the first pressure chamber 112 and discharged from the second pressure chamber 114, fluid also continues to flow in the first pressure chamber 112. Therefore, while fluid is supplied to the first pressure chamber 112 and discharged from the second pressure chamber 114, the magnetic chuck 10 is also cooled by the fluid.

[0068] If fluid is supplied to the first pressure chamber 112 and fluid begins to be discharged from the second pressure chamber 114, the force required to drive the piston assembly 14 upward is exerted on the piston assembly 14 due to the pressure difference between the first and second pressure chambers 112 and 114. The piston assembly 14 is at bottom dead center until the force required to drive the piston assembly 14 upward exceeds the magnetic attraction forces acting between the bottom yoke 80 and the piston assembly 14, and between the outer yoke 82 and the piston assembly 14. The piston assembly 14 begins to rise if the force required to drive the piston assembly 14 upward exceeds the magnetic attraction forces acting between the bottom yoke 80 and the piston assembly 14, and between the outer yoke 82 and the piston assembly 14.

[0069] The magnetic attraction force acting on the workpiece W gradually decreases as the piston assembly 14 rises, and the workpiece W is released from the magnetic chuck 10. The rising of the piston assembly 14 ends when the flange 41 of the sealing retainer 38 abuts against the upper shock absorber 104. That is, the piston assembly 14 reaches top dead center. For the piston assembly 14, in addition to the magnetic attraction force acting between the latching yoke 20 and the piston assembly 14, the differential pressure between the first pressure chamber 112 and the second pressure chamber 114 continues to be applied to the piston assembly 14, thus reliably holding the piston assembly 14 at top dead center. Therefore, the piston assembly 14 will not accidentally descend and attract the workpiece W. While the piston assembly 14 is held at top dead center, fluid also continues to flow within the first pressure chamber 112. Therefore, while the piston assembly 14 is held at top dead center, the magnetic chuck 10 is also cooled by the fluid.

[0070] Thus, according to this embodiment, the first pressure chamber 112 and the second pressure chamber 114 are connected via a connecting passage 71 (first connecting passage 71A). Therefore, according to this embodiment, each part of the magnetic chuck 10 is cooled by the fluid continuously flowing in the internal space 25 of the cylinder 12. Even when the piston assembly 14 is at bottom dead center, the fluid continues to flow in both the first and second pressure chambers 112 and 114. Therefore, according to this embodiment, when a high-temperature workpiece W is attracted by the magnetic chuck 10, damage to the first seal 62, the second seal 96, the piston seal 46, the lower shock absorber 98, etc., can be suppressed. Therefore, according to this embodiment, a magnetic chuck 10 with good heat resistance can be provided.

[0071] [Second Implementation]

[0072] Next, use Figure 5 and Figure 6 The magnetic chuck of the second embodiment will be described. Regarding... Figures 1-4 The same structural elements of the magnetic chuck in the first embodiment shown are labeled with the same symbols and are omitted or simplified in description. Figure 5 and Figure 6 This is a cross-sectional view showing the magnetic chuck of this embodiment. Figure 5 The text indicates that the piston assembly 14 is at top dead center. Figure 6 The text indicates that the piston assembly 14 is at the bottom dead center.

[0073] like Figure 5 and Figure 6 As shown, a groove 116 is formed on the wall of the internal space 25 of the cylinder 12. In this embodiment, the connecting passage 71 (second connecting passage 71B) connecting the first pressure chamber 112 and the second pressure chamber 114 is formed by the groove 116. In order to generate a sufficient differential pressure between the first pressure chamber 112 and the second pressure chamber 114 when driving the piston assembly 14, the depth and width of the groove 116 constituting the second connecting passage 71B are set to be sufficiently small. Similar to the first connecting passage 71A in the first embodiment, the second connecting passage 71B is formed on the second side portion 12g of the cylinder 12. As described above, the first side portion 12f and the second side portion 12g are located in opposite positions relative to each other with respect to the central axis C of the cylinder 12. The first side portion 12f of the cylinder 12 has a first feed port 26 and a second feed port 76, and the second side portion 12g of the cylinder 12 has the second connecting passage 71B.

[0074] The lower end of the groove 116 constituting the second connecting passage 71B reaches the lower shock absorber 98 with the groove 98a formed thereon. The first supply / discharge port 26 is connected to the second connecting passage 71B via the first pressure chamber 112. When the piston assembly 14 is at bottom dead center, as... Figure 6As shown, the first supply / discharge port 26 and the second connecting passage 71B are also maintained in a state where they are connected via the first pressure chamber 112.

[0075] The upper end of the groove 116 faces the outer peripheral surface of the small-diameter portion 20b in the latch yoke 20. As described above, a gap 114a is formed between the outer peripheral surface of the small-diameter portion 20b and the wall surface of the cylinder bore 24. As described above, the gap 114a is part of the second pressure chamber 114. The second feed port 76 and the second communication passage 71B are connected via the second pressure chamber 114. When the piston assembly 14 is at top dead center, as... Figure 5 As shown, the second supply / discharge port 76 and the second connecting passage 71B are also maintained in a state where they are connected via the second pressure chamber 114.

[0076] Furthermore, the above description uses the case where the second connecting path 71B is formed by one slot 116 as an example, but it is not limited to this. The second connecting path 71B can also be formed by multiple slots 116. For example, multiple slots 116 can be arranged at predetermined intervals in the circumferential direction of the cylinder bore 24.

[0077] Thus, a connecting passage 71 (second connecting passage 71B) can also be formed by a groove 116 formed on the wall of the internal space 25 of the cylinder 12. In this embodiment, the various parts of the magnetic chuck 10 are cooled by a fluid that continuously flows in the internal space 25 of the cylinder 12. That is, even when the piston assembly 14 is at bottom dead center, the fluid continues to flow in both the first pressure chamber 112 and the second pressure chamber 114. Therefore, when a high-temperature workpiece W is attracted by the magnetic chuck 10, damage to the first seal 62, the second seal 96, the piston seal 46, the lower shock absorber 98, etc., can be suppressed. Therefore, in this embodiment, a magnetic chuck 10 with good heat resistance can also be provided.

[0078] [Third Implementation Method]

[0079] Next, use Figure 7 and Figure 8 The magnetic chuck of the third embodiment will be described. Regarding... Figures 1-6 The same structural elements of the magnetic chuck in the first or second embodiment shown are marked with the same symbols and are omitted or simplified in description. Figure 7 and Figure 8 This is a cross-sectional view showing the magnetic chuck of this embodiment. Figure 7 The text indicates that the piston assembly 14 is at top dead center. Figure 8 The text indicates that the piston assembly 14 is at the bottom dead center.

[0080] like Figure 7 and Figure 8As shown, a circular hole-shaped recess 85 is formed in the sealing retainer 38, opening towards the upper surface of the magnetic chuck 10. The circular hole-shaped recess 85 opens at the bottom surface of the annular recess 51. The central axis of the circular hole-shaped recess 85 coincides with the central axis of the through hole 87a, which will be described later. Figure 7 and Figure 8 The image shows an example of a case where multiple circular recesses 85 are formed along the circumference of the piston assembly 14.

[0081] The piston assembly 14 also has a connecting passage 71 (third connecting passage 71C) that connects the first pressure chamber 112 and the second pressure chamber 114. The third connecting passage 71C is formed by interconnecting a through hole 87a through the seal holder 38, a through hole 87b through the permanent magnet 42, and a through hole 87c through the annular plate 45, but is not limited thereto. The third connecting passage 71C has an opening 83a communicating with the second pressure chamber 114 and an opening 83b communicating with the first pressure chamber 112. To generate a sufficient differential pressure between the first pressure chamber 112 and the second pressure chamber 114 when the piston assembly 14 is driven, the diameter of the third connecting passage 71C is set to be sufficiently small. Here, to generate a sufficient differential pressure between the first pressure chamber 112 and the second pressure chamber 114 when the piston assembly 14 is driven, the diameter of the through hole 87a is set to be sufficiently small. The third connecting passage 71C is formed at least between the central axis C of the cylinder 12 and the second side portion 12g. As described above, the first side portion 12f and the second side portion 12g are located in opposite positions relative to the central axis C of the cylinder 12. The first side portion 12f of the cylinder 12 has a first feed port 26 and a second feed port 76, and a third connecting passage 71C is disposed at least between the central axis C of the cylinder 12 and the second side portion 12g. Furthermore, in Figure 7 and Figure 8 The example shown is a case where multiple third connecting paths 71C are formed along the circumference of the piston assembly 14.

[0082] The first feed port 26 and the third connecting passage 71C are connected via the first pressure chamber 112. When the piston assembly 14 is at bottom dead center, as... Figure 8 As shown, the first supply / discharge port 26 and the third connecting passage 71C are also maintained in a state where they are connected via the first pressure chamber 112.

[0083] The second feed port 76 and the third connecting passage 71C are connected via the second pressure chamber 114. When the piston assembly 14 is at top dead center, as... Figure 7 As shown, the second supply port 76 and the third connecting passage 71C are also maintained in a state where they are connected via the second pressure chamber 114.

[0084] Thus, a connecting passage 71 (third connecting passage 71C) connecting the first pressure chamber 112 and the second pressure chamber 114 can also be formed in the piston assembly 14. In this embodiment, the various parts of the magnetic chuck 10 are cooled by a fluid continuously flowing in the internal space 25 of the cylinder 12. That is, even when the piston assembly 14 is at bottom dead center, the fluid continues to flow in both the first and second pressure chambers 112 and 114. Therefore, when a high-temperature workpiece W is attracted by the magnetic chuck 10, damage to the first seal 62, the second seal 96, the piston seal 46, the lower shock absorber 98, etc., can be suppressed. Therefore, in this embodiment, a magnetic chuck 10 with good heat resistance can also be provided.

[0085] [Fourth Implementation Method]

[0086] Next, use Figures 9-11 The magnetic chuck of the fourth embodiment will be described. Figure 9 This is a rear view showing the magnetic chuck of this embodiment. Figure 10 and Figure 11 This is a cross-sectional view showing the magnetic chuck of this embodiment. Figure 10 The text indicates that the piston assembly 14 is at top dead center. Figure 11 The text indicates that piston assembly 14 is at bottom dead center. (This is in contrast to...) Figures 1 to 8 The same structural elements of the magnetic chucks in the first to third embodiments shown are marked with the same symbols and are omitted or simplified in description.

[0087] In the magnetic chuck 10 of this embodiment, a directional control valve 134 is provided in the first connecting channel 71Aa.

[0088] Similar to the cylinder 12 described in the first to third embodiments, a connecting passage 71 is formed in the cylinder 12 to connect the first pressure chamber 112 and the second pressure chamber 114. The connecting passage 71 includes a first connecting passage 71Aa. A portion of the first connecting passage 71Aa is formed inside the wall 12a of the cylinder 12. The first connecting passage 71Aa is formed independently of the internal space 25 of the cylinder 12. Similar to the first connecting passage 71A described in the first embodiment, the first connecting passage 71Aa is provided on the second side portion 12g of the cylinder 12.

[0089] The first connecting path 71Aa includes a first connecting hole 74a. The first connecting hole 74a in this embodiment is the same as the first connecting hole 74a described in the first embodiment.

[0090] The first connecting passage 71Aa also includes a third connecting hole 74c. A hole 118 is formed inside the wall 12a of the cylinder 12. The hole 118 extends downwards from the wall 12a of the cylinder 12. The hole 118 penetrates the recess 73. The portion of the hole 118 located below the recess 73 constitutes the third connecting hole 74c. The upper portion of the hole 118 is closed by a sealing member 120. The upper end of the third connecting hole 74c opens on the side of the recess 73. The third connecting hole 74c extends downwards from the wall 12a of the cylinder 12.

[0091] The first connecting passage 71Aa also includes a fourth connecting hole 74d. The lower end of the third connecting hole 74c is connected to one end of the fourth connecting hole 74d. The other end of the fourth connecting hole 74d opens at the second side surface 13B of the cylinder 12.

[0092] The first connecting passage 71Aa also includes a fifth connecting hole 74e. The upper end of the fifth connecting hole 74e communicates with the threaded hole 130 described later. The lower end of the fifth connecting hole 74e reaches the annular recess 30 formed in the cylinder 12. Similar to the first connecting passage 71A described in the first embodiment, the first connecting passage 71Aa communicates with the first pressure chamber 112 via a groove 98a formed in the lower shock absorber 98. That is, the fifth connecting hole 74e has an opening 79b communicating with the first pressure chamber 112. The opening 79b communicating with the first pressure chamber 112 is provided on the second side portion 12g of the cylinder 12.

[0093] A flow path block 122 is installed on the wall 12a of the cylinder 12. The flow path block 122 is installed on the second side 12g of the cylinder 12. In other words, the flow path block 122 is installed on the back side of the magnetic chuck 10. The flow path block 122 has a side 123A and a side 123B. Side 123A and side 123B are located opposite to each other. Side 123A of the flow path block 122 is in contact with the second side 13B of the cylinder 12.

[0094] An internal flow path 124 is formed inside the flow path block 122. The first connecting path 71Aa also includes the internal flow path 124. The internal flow path 124 includes a sixth connecting hole 74f. A stepped portion 144 for mounting a seal 142 is formed on the side surface 123A of the flow path block 122. One end of the sixth connecting hole 74f opens in the stepped portion 144. The central axis of the sixth connecting hole 74f coincides with the central axis of the fourth connecting hole 74d. One end of the sixth connecting hole 74f communicates with the fourth connecting hole 74d. The other end of the sixth connecting hole 74f opens in the bottom surface of the recess 132 (described later). A seal 142 is mounted on the stepped portion 144. The seal 142 seals the second side surface 13B of the cylinder 12 with the side surface 123A of the flow path block 122. The material of the seal 142 may be, for example, fluororubber, but is not limited thereto.

[0095] The flow path 124 within the block also includes a seventh connecting hole 74g. A hole 126 is formed inside the flow path block 122. The hole 126 extends upward inside the flow path block 122. The hole 126 penetrates the through hole 146 (described later). The hole 126 reaches the side of the recess 132. The portion of the hole 126 located between the through hole 146 and the recess 132 constitutes the seventh connecting hole 74g. The lower portion of the hole 126 is closed by a sealing member 128. The upper end of the seventh connecting hole 74g opens into the side of the recess 132. The lower end of the seventh connecting hole 74g opens into the side of the through hole 146.

[0096] A threaded hole 130 is formed inside the wall 12a of the cylinder 12. The top end of the hollow bolt 154 (described later) is screwed into the threaded hole 130. One end of the threaded hole 130 communicates with the fifth connecting hole 74e. The other end of the threaded hole 130 opens on the second side 13B of the cylinder 12. The threaded hole 130 forms part of the first connecting passage 71Aa.

[0097] A recess 132 is formed in the flow path block 122. The recess 132 opens on the side 123B of the flow path block 122. The depth direction of the recess 132 is from the side 123B toward the side 123A. The bottom surface of the recess 132 forms a valve seat 132a for the valve core 134c described later to abut against.

[0098] A directional control valve 134 for controlling the direction of fluid flow is installed in the recess 132. A check valve 134A is used as the directional control valve 134. The check valve 134A has a support portion 134a, a spring 134b, and a valve core 134c. The valve core 134c is actuated relative to the support portion 134a. The direction of actuation of the valve core 134c is along the central axis of the support portion 134a. That is, the direction of actuation of the valve core 134c is the depth direction of the recess 132. The spring 134b elastically applies force to the valve core 134c towards the valve seat 132a. When the pressure in the sixth connecting hole 74f is higher than the pressure in the seventh connecting hole 74g, the following first and second forces are applied to the valve core 134c. The first force is the force applied to the valve core 134c corresponding to the pressure difference between the seventh connecting hole 74g and the sixth connecting hole 74f. The second force is the force applied to the valve core 134c by the spring 134b. The directions of the first force and the second force are opposite to each other. When the first force is greater than the second force, the one-way valve 134A opens. That is, when the pressure in the sixth connecting hole 74f is sufficiently higher than the pressure in the seventh connecting hole 74g, the one-way valve 134A opens. When the first force is less than the second force, the one-way valve 134A closes. Furthermore, when the pressure in the sixth connecting hole 74f is lower than the pressure in the seventh connecting hole 74g, the one-way valve 134A closes. The one-way valve 134A allows fluid to flow from the second pressure chamber 114 towards the first pressure chamber 112 via the first connecting passage 71Aa. The one-way valve 134A prevents fluid from flowing from the first pressure chamber 112 towards the second pressure chamber 114 via the first connecting passage 71Aa.

[0099] A stepped portion 136 is formed in the recess 132 for mounting a retaining ring (C-shaped retaining ring) 138. The retaining ring 138 is mounted in the stepped portion 136. The directional control valve 134 is fixed in the recess 132 by the retaining ring 138.

[0100] A seal 140 is installed on the directional control valve 134. The seal 140 seals the directional control valve 134 between the valve and the recess 132. The material of the seal 140 may be, for example, fluororubber, but is not limited thereto.

[0101] A through hole 146 is formed in the flow path block 122. The central axis of the through hole 146 coincides with the central axis of the threaded hole 130. A stepped portion 148 for mounting the seal 150 is formed on the side surface 123A of the flow path block 122. One end of the through hole 146 opens in the stepped portion 148. One end of the through hole 146 communicates with the threaded hole 130. A recess 152 for receiving the head 154a of the hollow bolt 154 is formed on the side surface 123B of the flow path block 122. The other end of the through hole 146 opens in the bottom surface of the recess 152.

[0102] The flow path block 122 is mounted to the wall 12a of the cylinder 12 using a hollow bolt 154. The hollow bolt 154 has a cavity 154b. The central axis of the cavity 154b is aligned with the central axis of the hollow bolt 154. A hole 154c is formed in the hollow bolt 154, leading to the cavity 154b. The central axis of the hole 154c intersects the central axis of the cavity 154b. One end of the cavity 154b communicates with the seventh connecting hole 74g via the hole 154c and the through hole 146. The other end of the cavity 154b communicates with the threaded hole 130. The cavity 154b forms part of the flow path 124 within the block.

[0103] A washer 156 is installed in the recess 152. The washer 156 seals the space between the hollow bolt 154 and the flow path block 122.

[0104] The thickness of the upper portion 122a of the flow path block 122 is thinner than the thickness of the rest of the flow path block 122. A through hole 158 is formed in the upper portion 122a of the flow path block 122. The central axis of the through hole 158 coincides with the central axis of the recess 73. The recess 73 is a threaded hole. The top end of the flow regulating valve 72 is screwed into the recess 73. The upper portion 122a of the flow path block 122 is mounted to the wall 12a of the cylinder 12 using the flow regulating valve 72.

[0105] When fluid is supplied to the second pressure chamber 114 and fluid begins to be discharged from the first pressure chamber 112, a pressure differential is generated between the first pressure chamber 112 and the second pressure chamber 114. That is, the force required to drive the piston assembly 14 in the direction from the second pressure chamber 114 towards the first pressure chamber 112 acts on the piston assembly 14 in accordance with the pressure differential between the first and second pressure chambers 112. The first pressure chamber 112 is connected to the seventh connecting hole 74g, and the second pressure chamber 114 is connected to the sixth connecting hole 74f. Therefore, when the force required to drive the piston assembly 14 acts in the direction from the second pressure chamber 114 towards the first pressure chamber 112, the force required to open the check valve 134A acts on the check valve 134A. That is, the force required to open the check valve 134A acts on the check valve 134A in accordance with the pressure differential between the first and second pressure chambers 112 and the second pressure chamber 114. The check valve 134A opens when the pressure in the second pressure chamber 114 is sufficiently higher than the pressure in the first pressure chamber 112. That is, the check valve 134A opens when the pressure in the sixth connecting hole 74f is sufficiently higher than the pressure in the seventh connecting hole 74g.

[0106] If fluid is supplied to the first pressure chamber 112 and fluid is discharged from the second pressure chamber 114, a pressure differential is generated between the first pressure chamber 112 and the second pressure chamber 114. That is, the force required to drive the piston assembly 14 in the direction from the first pressure chamber 112 toward the second pressure chamber 114 acts on the piston assembly 14 corresponding to the pressure differential between the first and second pressure chambers 112. As described above, the first pressure chamber 112 is connected to the seventh communication port 74g, and the second pressure chamber 114 is connected to the sixth communication port 74f. Therefore, the pressure in the sixth communication port 74f is lower than the pressure in the seventh communication port 74g. Therefore, when the force required to drive the piston assembly 14 acts in the direction from the first pressure chamber 112 toward the second pressure chamber 114, the one-way valve 134A closes. Furthermore, if the directional control valve 134 is closed, after the piston assembly 14 reaches top dead center (see reference...), Figure 10 During this stage, the workpiece W is released from the magnetic chuck 10, so the magnetic chuck 10 is not heated by the workpiece W. That is, during this stage, there is no need to cool the magnetic chuck 10 with fluid. Therefore, there is no particular problem even if the fluid does not flow into the first pressure chamber 112.

[0107] Thus, in this embodiment, when the force driving the piston assembly 14 acts in the direction from the first pressure chamber 112 toward the second pressure chamber 114, the directional control valve 134 is closed. According to this embodiment, since the directional control valve 134 is closed, fluid waste can be prevented.

[0108] (Modified Example)

[0109] Next, use Figure 12 and Figure 13 The magnetic chuck of a modified embodiment of this invention will be described. Figure 12 This is a cross-sectional view showing a portion of the magnetic chuck of this embodiment. Figure 12 The text indicates that the piston assembly 14 is at top dead center. Figure 13 This is a block diagram illustrating the magnetic chuck of this embodiment.

[0110] In the magnetic chuck 10 of this modified example, an electromagnetic directional control valve 134B is used as the directional control valve 134.

[0111] Similar to the cylinder 12 described in the first to third embodiments, a connecting passage 71 is formed in the cylinder 12 to connect the first pressure chamber 112 and the second pressure chamber 114. The connecting passage 71 includes a first connecting passage 71Ab. A portion of the first connecting passage 71Ab is formed inside the wall 12a of the cylinder 12. The first connecting passage 71Ab is formed independently of the internal space 25 of the cylinder 12. Similar to the first connecting passage 71A described in the first embodiment, the first connecting passage 71Ab is provided on the second side portion 12g of the cylinder 12.

[0112] The first connecting path 71Ab includes a first connecting hole 74a. The first connecting hole 74a in this embodiment is the same as the first connecting hole 74a described in the first embodiment.

[0113] The first connecting passage 71Ab also includes a third connecting hole 74c. A hole 118 is formed inside the wall 12a of the cylinder 12. The hole 118 extends downwards from the wall 12a of the cylinder 12. The hole 118 penetrates the recess 73. The portion of the hole 118 located below the recess 73 constitutes the third connecting hole 74c. The upper portion of the hole 118 is closed by a sealing member 120. The upper end of the third connecting hole 74c opens on the side of the recess 73. The third connecting hole 74c extends downwards from the wall 12a of the cylinder 12. The lower end of the third connecting hole 74c opens on the side of the port 160A, described later.

[0114] A port 160A is formed in the wall 12a of the cylinder 12. The port 160A opens on the second side 13B of the cylinder 12. The port 160A communicates with the third connecting hole 74c.

[0115] A port 160B is formed in the wall 12a of the cylinder 12. The port 160B is located below the port 160A. The port 160B opens in the second side 13B of the cylinder 12. The port 160B communicates with the fifth connecting hole 74e.

[0116] like Figure 13 As shown, the electromagnetic directional control valve 134B has ports 164A and 164B. Port 164A is connected to port 160A via flow path 166A. Port 164B is connected to port 160B via flow path 166B.

[0117] The electromagnetic directional control valve 168 has ports 170A, 170B, and 170C. Fluid is supplied to port 170A via flow path 172. Port 170B is connected to the second inlet / outlet port 76 via flow path 174A. Port 170C is connected to the first inlet / outlet port 26 via flow path 174B.

[0118] The control device 176 controls the magnetic chuck 10. The control device 176 includes, for example, an arithmetic unit (processing unit) and a storage unit (not shown). The arithmetic unit is, for example, a processor such as a CPU (Central Processing Unit). That is, the arithmetic unit is composed of processing circuitry. The program stored in the storage unit is executed by the arithmetic unit, thereby controlling the magnetic chuck 10.

[0119] The control device 176 switches the solenoid directional control valves 134B and 168 according to the signal supplied from the control device 176. The control device 176 switches the solenoid directional control valve 168 to supply fluid into the second pressure chamber 114 via the second inlet / outlet port 76. While fluid is being supplied into the second pressure chamber 114 via the second inlet / outlet port 76, the control device 176 switches the solenoid directional control valve 134B to allow fluid flow in the first connecting passage 71Ab. That is, in this case, the control device 176 opens the solenoid directional control valve 134B, allowing fluid flow in the first connecting passage 71Ab. Thus, fluid is introduced into the first pressure chamber 112 via the first connecting passage 71Ab.

[0120] Additionally, control device 176 switches solenoid directional control valve 168 to supply fluid to the first pressure chamber 112 via the first inlet / outlet port 26. While fluid is being supplied to the first pressure chamber 112 via the first inlet / outlet port 26, control device 176 switches solenoid directional control valve 134B to prevent fluid flow in the first connecting passage 71Ab. That is, in this case, control device 176 closes solenoid directional control valve 134B, preventing fluid flow in the first connecting passage 71Ab. This prevents fluid from flowing from the first pressure chamber 112 to the second pressure chamber 114 via the first connecting passage 71Ab.

[0121] In this variation, the directional control valve 134 is closed when the force driving the piston assembly 14 acts in the direction from the first pressure chamber 112 toward the second pressure chamber 114. Therefore, in this variation, fluid waste can also be prevented.

[0122] [Modified Implementation]

[0123] The above describes preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

[0124] For example, the first and second embodiments can be combined. That is, the magnetic chuck 10 can also have a first connecting path 71A and a second connecting path 71B.

[0125] Alternatively, the first and third embodiments can be combined. That is, the magnetic chuck 10 can also have a first connecting path 71A and a third connecting path 71C.

[0126] Alternatively, the second and third embodiments can be combined. That is, the magnetic chuck 10 can also have a second connecting path 71B and a third connecting path 71C.

[0127] Alternatively, the first, second, and third embodiments can be combined. That is, the magnetic chuck 10 can also have a first connecting path 71A, a second connecting path 71B, and a third connecting path 71C.

[0128] Alternatively, the fourth embodiment and the second embodiment can be combined. That is, the magnetic chuck 10 can also have a first connecting path 71Aa and a second connecting path 71B. Alternatively, a variation of the fourth embodiment can be combined with the second embodiment. That is, the magnetic chuck 10 can also have a first connecting path 71Ab and a second connecting path 71B.

[0129] Alternatively, the fourth and third embodiments can be combined. That is, the magnetic chuck 10 can also have a first connecting path 71Aa and a third connecting path 71C. Alternatively, a variation of the fourth embodiment can be combined with the third embodiment. That is, the magnetic chuck 10 can also have a first connecting path 71Ab and a third connecting path 71C.

[0130] Alternatively, the fourth, second, and third embodiments can be combined. That is, the magnetic chuck 10 can also include a first connecting path 71Aa, a second connecting path 71B, and a third connecting path 71C. Alternatively, variations of the fourth embodiment, the second embodiment, and the third embodiment can also be combined. That is, the magnetic chuck 10 can also include a first connecting path 71Ab, a second connecting path 71B, and a third connecting path 71C.

[0131] The above implementation methods can be summarized as follows.

[0132] The magnetic chuck (10) comprises: a cylinder (12) having a workpiece adsorption surface (12c) for adsorbing workpieces (W); a piston assembly (14) including a permanent magnet (42) and movable within the internal space (25) of the cylinder, dividing the internal space of the cylinder into a first pressure chamber (112) and a second pressure chamber (114); a first outlet (26) formed in the cylinder and communicating with the first pressure chamber; a second outlet (76) formed in the cylinder and communicating with the second pressure chamber; and a connecting passage (71) connecting the first pressure chamber and the second pressure chamber. With this structure, a connecting passage is formed connecting the first pressure chamber and the second pressure chamber, thus allowing fluid to continuously flow within both the first and second pressure chambers. Even when the piston assembly is at bottom dead center, fluid continues to flow within both the first and second pressure chambers. Therefore, even when a workpiece at high temperature is adsorbed by the magnetic chuck, damage to the structural elements of the magnetic chuck can be suppressed. Therefore, based on this structure, a magnetic chuck with good heat resistance can be provided.

[0133] Alternatively, the connecting path may include a first connecting path (71A, 71Aa, 71Ab), at least a portion of which is formed inside the wall (12a) of the cylinder. The first connecting path is formed independently of the internal space of the cylinder. The first connecting path has an opening (79b) communicating with the first pressure chamber and an opening (79a) communicating with the second pressure chamber.

[0134] Alternatively, the magnetic chuck may also include a shock absorber (98) that mitigates the impact generated when the piston assembly moves within the internal space, and the first communication path communicates with the first pressure chamber via a groove (98a) formed in the shock absorber.

[0135] Alternatively, the first outlet can communicate with the first pressure chamber via another groove (98a) formed in the shock absorber.

[0136] Alternatively, the magnetic chuck may also include a flow control valve (72) for adjusting the flow rate of the fluid flowing in the first connecting path. With this configuration, the flow rate of the fluid flowing in the first connecting path can be appropriately adjusted.

[0137] Alternatively, the cylinder may include a first end (12d) containing the workpiece adsorption surface and a second end (12e) opposite to the first end, with the flow regulating valve located at the second end. With this structure, the distance between the workpiece and the flow regulating valve can be sufficiently ensured, thus effectively suppressing damage to the seals or other components of the flow regulating valve.

[0138] Alternatively, the first connecting passage may include a connecting hole (74a) having an opening communicating with the second pressure chamber, the central axis of which coincides with the central axis of the flow regulating valve.

[0139] Alternatively, the first connecting passage (71Aa, 71Ab) may also include a directional control valve (134) that controls the direction of fluid flow. The first pressure chamber is located between the second pressure chamber and the workpiece adsorption surface. When the force driving the piston assembly acts in the direction from the second pressure chamber toward the first pressure chamber, the directional control valve opens; when the force driving the piston assembly acts in the direction from the first pressure chamber toward the second pressure chamber, the directional control valve closes. This structure prevents fluid waste.

[0140] Alternatively, the directional control valve may be a one-way valve (134A), which allows the fluid to flow from the second pressure chamber toward the first pressure chamber via the first connecting passage, and prevents the fluid from flowing from the first pressure chamber toward the second pressure chamber via the first connecting passage.

[0141] Alternatively, the magnetic chuck may also include a flow path block (122) mounted on the wall of the cylinder, the first connecting passage having an in-block flow path (124) formed inside the flow path block, and the one-way valve disposed on the flow path block.

[0142] Alternatively, the flow path block can be mounted to the wall of the cylinder using hollow bolts (154), with the hollow bolts forming part of the flow path within the block through their holes (154b). This structure facilitates the miniaturization of magnetic chucks, among other things.

[0143] Alternatively, the directional control valve may be an electromagnetic directional control valve (134B) that switches according to a signal supplied from the control device. When fluid is supplied to the second pressure chamber via the second outlet, the electromagnetic directional control valve is switched to allow the flow of the fluid in the first communication path. When fluid is supplied to the first pressure chamber via the first outlet, the electromagnetic directional control valve is switched to prevent the flow of the fluid in the first communication path.

[0144] Alternatively, the connecting path may include a second connecting path (71B), which is formed by a groove (116) formed on the wall of the internal space of the cylinder.

[0145] Alternatively, the communication path may include a third communication path (71C) formed in the piston assembly, the third communication path having an opening (83b) communicating with the first pressure chamber and an opening (83a) communicating with the second pressure chamber.

[0146] Alternatively, the cylinder may include a first side (12f) and a second side (12g) located opposite each other with respect to the central axis (C) of the cylinder. The first and second feed ports are disposed on the first side, and the connecting passage is disposed at least on the second side or between the second side and the central axis. With this structure, the structural elements of the magnetic chuck can be cooled more effectively, thus providing a magnetic chuck with better heat resistance.

Claims

1. A magnetic chuck (10), characterized in that, have: Cylinder (12), which has a workpiece adsorption surface (12c) for adsorbing workpiece (W); Piston assembly (14) includes a permanent magnet (42) and is movable within the internal space (25) of the cylinder, dividing the internal space of the cylinder into a first pressure chamber (112) and a second pressure chamber (114). The first supply port (26) is formed in the cylinder and communicates with the first pressure chamber; The second supply port (76) is formed in the cylinder and communicates with the second pressure chamber; A connecting passage (71), formed independently of the first and second feed ports, connects the first and second pressure chambers and, via the internal space, connects the first and second feed ports; and A flow regulating valve (72) having a mandrel that throttles the flow through the connecting passage. If the mandrel is rotated, the mandrel will be displaced along its length. The flow rate of the fluid flowing in the connecting passage is adjusted corresponding to the position of the mandrel in the length direction, which is determined by the amount of rotation of the mandrel. When fluid is discharged from the first pressure chamber via the first outlet, and the pressure in the first pressure chamber is less than the pressure in the second pressure chamber, the fluid supplied to the second pressure chamber via the second outlet is also supplied to the first pressure chamber via the connecting passage.

2. The magnetic chuck according to claim 1, characterized in that, The connecting path includes a first connecting path (71A, 71Aa, 71Ab). At least a portion of the first connecting passage is formed inside the wall (12a) of the cylinder. The first connecting path is formed independently of the internal space of the cylinder. The first connecting passage has an opening (79b) communicating with the first pressure chamber and an opening (79a) communicating with the second pressure chamber.

3. The magnetic chuck according to claim 2, characterized in that, The magnetic chuck also includes a shock absorber (98) that mitigates the impact generated when the piston assembly moves within the internal space. The first connecting path is connected to the first pressure chamber via a groove (98a) formed in the shock absorber.

4. The magnetic chuck according to claim 3, characterized in that, The first outlet communicates with the first pressure chamber via another groove (98a) formed in the shock absorber.

5. The magnetic chuck according to claim 2, characterized in that, The flow regulating valve has a main body, the mandrel is inserted into the main body in a displaceable manner, and the flow regulating valve is used to adjust the flow rate.

6. The magnetic chuck according to claim 5, characterized in that, The cylinder includes a first end (12d) containing the workpiece adsorption surface and a second end (12e) opposite to the first end. The flow regulating valve is provided at the second end.

7. The magnetic chuck according to claim 6, characterized in that, The first connecting passage includes a connecting hole (74a) having an opening communicating with the second pressure chamber. The central axis of the connecting hole is aligned with the central axis of the flow regulating valve.

8. The magnetic chuck according to claim 2, characterized in that, The first connecting passage (71Aa, 71Ab) also includes a directional control valve (134), which controls the direction of fluid flow. The first pressure chamber is located between the second pressure chamber and the workpiece adsorption surface. When the force required to drive the piston assembly acts in the direction from the second pressure chamber toward the first pressure chamber, the directional control valve opens. The directional control valve closes when the force required to drive the piston assembly acts in the direction from the first pressure chamber toward the second pressure chamber.

9. The magnetic chuck according to claim 8, characterized in that, The directional control valve is a one-way valve (134A). The one-way valve allows fluid to flow from the second pressure chamber toward the first pressure chamber via the first connection, and prevents fluid from flowing from the first pressure chamber toward the second pressure chamber via the first connection.

10. The magnetic chuck according to claim 9, characterized in that, The magnetic chuck also includes a flow path block (122), which is mounted on the wall of the cylinder. The first connecting path has an intra-block flow path (124) formed inside the flow path block. The one-way valve is located in the flow path block.

11. The magnetic chuck according to claim 10, characterized in that, The flow path block is mounted to the wall of the cylinder using hollow bolts (154). The hollow bolt forms part of the flow path within the block through its cavity (154b).

12. The magnetic chuck according to claim 8, characterized in that, The directional control valve is an electromagnetic directional control valve (134B) that switches according to a signal supplied from the control device. When the fluid is supplied to the second pressure chamber via the second inlet / outlet, the electromagnetic directional control valve is switched to allow the flow of the fluid in the first communication path; when the fluid is supplied to the first pressure chamber via the first inlet / outlet, the electromagnetic directional control valve is switched to prevent the flow of the fluid in the first communication path.

13. The magnetic chuck according to any one of claims 1 to 12, characterized in that, The connecting path includes a second connecting path (71B), which is formed by a groove (116) formed on the wall of the internal space of the cylinder.

14. The magnetic chuck according to any one of claims 1 to 12, characterized in that, The connecting passage includes a third connecting passage (71C) formed in the piston assembly. The third connecting passage has an opening (83b) communicating with the first pressure chamber and an opening (83a) communicating with the second pressure chamber.

15. The magnetic chuck according to any one of claims 1 to 12, characterized in that, The cylinder includes a first side (12f) and a second side (12g) located opposite each other with respect to the central axis (C) of the cylinder. The first and second water inlets / outlets are located on the first side. The connecting path is at least located on the second side or between the second side and the central axis.

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