Magnetic Gripper

Abstract

Visually determine whether the magnetic gripper is in a state where it can attract the workpiece. [Solution] The magnetic gripper 10 is a magnetic gripper for attracting a workpiece W, and comprises a permanent electromagnet 12 including a first permanent magnet 12a and a second permanent magnet 12b, a coil 14 wound at least around the outer circumference of the second permanent magnet 12b and capable of reversing the magnetization direction of the second permanent magnet 12b when an electric current flows through it, a yoke 16 housing the permanent electromagnet 12 inside, and a display sheet 30 having a medium made of photocrystals of magnetic particles and whose color changes in accordance with the reversal of the magnetization direction of the second permanent magnet 12b. By visually observing the color change shown on the display sheet through a window, it is possible to determine whether or not the magnetic gripper 10 is in a state where it can attract a workpiece W.

Description

Technical Field

[0001] The present disclosure relates to a magnet gripper.

Background Art

[0002] Japanese Patent Laid-Open No. 60-130106 discloses a permanent magnet type adsorption device. When a magnetic body is adsorbed, a low magnetic force magnet is magnetized in the same direction as a high magnetic force magnet, and when not adsorbed, the low magnetic force magnet is magnetized in the opposite direction to the high magnetic force magnet.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] From the appearance of a magnet gripper having a permanent magnet, the magnetic force generated by the permanent magnet cannot be visually detected. That is, there is a problem that it is impossible to determine whether the magnet gripper is in a state where it can adsorb a workpiece.

[0005] The present disclosure aims to solve the above-described problems.

Means for Solving the Problems

[0006] An aspect of the present disclosure is a magnet gripper that adsorbs a workpiece, including a permanent magnet including a first permanent magnet and a second permanent magnet, a coil wound around at least the outer periphery of the second permanent magnet and capable of reversing the magnetization direction of the second permanent magnet when an electric current flows, a yoke that houses the permanent magnet inside, and a display sheet having a medium using a photonic crystal made of magnetic particles, the color of which changes according to the reversal of the magnetization direction of the second permanent magnet.

Effects of the Invention

[0007] According to this disclosure, it is possible to determine whether or not the magnetic gripper is in a state where it can attract a workpiece. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing an example configuration of a magnetic gripper that attracts a workpiece. [Figure 2] Figures 2A and 2B schematically show examples of the configuration of a display sheet. [Figure 3] Figures 3A and 3B schematically show the magnetic flux corresponding to the magnetic force generated by a permanent electromagnet. [Figure 4] Figures 4A and 4B schematically illustrate other configurations of the magnetic gripper, respectively. [Modes for carrying out the invention]

[0009] Figure 1 is a schematic diagram showing an example configuration of a magnetic gripper 10 for attracting a workpiece W. The magnetic gripper 10 includes a permanent electromagnet 12, a coil 14, a yoke 16, a cover member 20, and a display sheet 30. The magnetic gripper 10 may also be provided with a connector for connecting to a power supply, an adapter for attaching the magnetic gripper 10 to a robot arm, etc., but these are omitted from the illustration in Figure 1. The permanent electromagnet 12 includes a first permanent magnet 12a and a second permanent magnet 12b. In this embodiment, as shown in Figure 1, the first permanent magnet 12a and the second permanent magnet 12b are arranged adjacent to each other.

[0010] Specifically, the cylindrical first permanent magnet 12a covers the outer surface of the cylindrical second permanent magnet 12b. That is, the second permanent magnet 12b is housed in the hollow part of the first permanent magnet 12a. The first permanent magnet 12a is a neodymium magnet containing, for example, neodymium in addition to iron. The second permanent magnet 12b is an alnico magnet containing, for example, aluminum, nickel, and cobalt in addition to iron.

[0011] The coil 14 is wound around at least the outer circumference of the second permanent magnet 12b. In this embodiment, as shown in Figure 1, the coil 14 is wound around the outer circumference of the first permanent magnet 12a, which is located further outside the second permanent magnet 12b. The coil 14 is electrically connected to a power supply (not shown). By applying a voltage to the coil 14 and causing a current to flow, the magnetization direction of the second permanent magnet 12b can be reversed.

[0012] The yoke 16 houses the permanent electromagnet 12 inside. The yoke 16 is made of ferromagnetic steel and allows magnetic flux corresponding to the magnetic force generated by the permanent electromagnet 12 to pass through it. The yoke 16 has a top yoke 16t, a bottom yoke 16b, and an outer yoke 16u. The top yoke 16t and the bottom yoke 16b are arranged in a direction intersecting the magnetization directions of the first permanent magnet 12a and the second permanent magnet 12b.

[0013] A non-magnetic material Nm is placed between the top yoke 16t and the outer yoke 16u. The non-magnetic material Nm is made of, for example, stainless steel. The top yoke 16t and the non-magnetic material Nm are held in place by the outer yoke 16u and a pad Rd positioned on the outer circumference of the outer yoke 16u.

[0014] Assume that the magnetization direction of the second permanent magnet 12b is opposite to that of the first permanent magnet 12a. In this case, by applying a voltage to the coil 14 and causing a current to flow through the coil 14 in a predetermined direction, the magnetization direction of the second permanent magnet 12b can be reversed to match that of the first permanent magnet 12a. If the workpiece W is a magnetic material, the workpiece W is attracted toward the top yoke 16t by the magnetic force generated by the permanent electromagnet 12 and is attracted to the magnetic gripper 10.

[0015] Even after the voltage applied to coil 14 is stopped and the current flowing through coil 14 ceases, the magnetic force attracting the workpiece W is maintained. Therefore, the workpiece W remains attracted to the magnetic gripper 10.

[0016] Subsequently, when a voltage is applied to the coil 14, a current flows through the coil 14 in the opposite direction to the predetermined direction described above, thereby reversing the magnetization direction of the second permanent magnet 12b to the opposite direction to that of the first permanent magnet 12a. As the magnetic force generated by the permanent electromagnet 12 no longer affects the workpiece W, the magnetic gripper 10's attraction to the workpiece W is released. Even after the voltage application to the coil 14 is stopped and the current flowing through the coil 14 stops, the magnetic gripper 10's attraction to the workpiece W remains released.

[0017] The outer yoke 16u extends in a direction intersecting the top yoke 16t and the bottom yoke 16b. In this embodiment, as shown in Figure 1, the outer yoke 16u surrounds and covers the permanent electromagnet 12 and the coil 14. The outer yoke 16u is in contact with the non-magnetic material Nm and the bottom yoke 16b. The cover member 20 surrounds and covers the outer yoke 16u. The cover member 20 also covers the bottom yoke 16b.

[0018] The display sheet 30 is provided on at least one of the outer surface of the top yoke 16t and the outer surface of the cover member 20 that covers the outer yoke 16u. That is, the display sheet 30 is provided on the outside of the yoke 16. In this embodiment, the display sheet 30 is provided on both the outer surface of the top yoke 16t and the outer surface of the cover member 20 that covers the outer yoke 16u.

[0019] The display sheet 30 comprises a medium using a photocrystal made of magnetic particles and a light-shielding sheet laminated on the medium. The medium contains a large number of magnetic particles in a dispersed state. When magnetic flux passes through the medium, the spacing between particles changes. This changes the wavelength of the reflected light when light incident on the medium from the outside is Bragg-reflected by the photocrystal made of particles. In other words, the color of the light reflected from the medium changes depending on whether or not magnetic flux passes through the medium. The stronger the magnetic flux passing through the medium, the shorter the wavelength of the reflected light from the medium becomes, so the color shown on the display sheet 30 approaches green, blue, or purple.

[0020] Depending on the reversal of the magnetization direction of the second permanent magnet 12b, there are cases where the magnetic flux corresponding to the magnetic force generated by the permanent electromagnetic magnet 12 passes through the medium and cases where it does not. Therefore, the color indicated by the display sheet 30 changes according to the reversal of the magnetization direction of the second permanent magnet 12b. In other words, the display sheet 30 is provided at a position where the color changes according to the reversal of the magnetization direction of the second permanent magnet 12b.

[0021] As will be described later using FIGS. 2A and 2B, the light shielding sheet has a window portion, and in regions other than the window portion, it shields external light so that it does not enter the medium. An operator can visually recognize the change in the color indicated by the display sheet 30 through the window portion. Thereby, it is possible to determine whether or not the magnet gripper 10 is in a state where it can adsorb the work W.

[0022] FIGS. 2A and 2B are diagrams schematically showing a configuration example of the display sheet 30. As described above, the display sheet 30 has a medium 30a and a light shielding sheet 30b. As shown in FIGS. 2A and 2B, the light shielding sheet 30b is laminated on the medium 30a and has a window portion 30t. The window portion 30t is formed by circularly cutting out a part of the light shielding sheet 30b.

[0023] The window portion 3透過する。これにより、マグネットグリッパ10がワークWを吸着可能な状態であるか否かが、より判別しやすくなる。窓部30tは、永電磁石12により生じる磁力に応じた磁束が媒体30aを通る場合に、より強力な磁束が媒体30aを通る位置に配置されることが好ましい。これにより,表示シート30が示す色の変化が、より明瞭になる。

[0024] FIGS. 3A and 3B are diagrams schematically showing the magnetic flux Mb corresponding to the magnetic force generated by the permanent electromagnetic magnet 12. In FIGS. 3A and 3B, illustration of the cover member 20 and the pad Rd among the magnet gripper 10 shown in FIG. 1 is omitted.

[0025] Figure 3A shows the magnetic flux Mb when the magnetization direction of the second permanent magnet 12b is opposite to that of the first permanent magnet 12a. Much of the magnetic flux Mb emanating from the first permanent magnet 12a enters the second permanent magnet 12b, and much of the magnetic flux Mb emanating from the second permanent magnet 12b enters the first permanent magnet 12a. In other words, a large amount of magnetic flux Mb is confined within the permanent electromagnet 12 and the yoke 16.

[0026] A portion of the magnetic flux Mb emanating from the first permanent magnet 12a returns to the first permanent magnet 12a through the yoke 16 rather than through the second permanent magnet 12b. However, the magnetic flux Mb passing through the first permanent magnet 12a, the second permanent magnet 12b, the top yoke 16t, the outer yoke 16u and / or the bottom yoke 16b hardly leaves the yoke 16. Therefore, as described above, the magnetic flux Mb hardly passes through the medium 30a of the unillustrated display sheet 30 located outside the yoke 16. Also, since the magnetic flux Mb hardly passes through the unillustrated workpiece W located outside the outer yoke 16u, the workpiece W is not attracted to the magnetic gripper 10.

[0027] Figure 3B shows the magnetic flux Mb when the magnetization direction of the second permanent magnet 12b is the same as the magnetization direction of the first permanent magnet 12a. Unlike Figure 3A, there is almost no magnetic flux Mb entering the second permanent magnet 12b from the first permanent magnet 12a. There is also almost no magnetic flux Mb entering the first permanent magnet 12a from the second permanent magnet 12b.

[0028] Much of the magnetic flux Mb emitted from the first permanent magnet 12a returns to the first permanent magnet 12a. Much of the magnetic flux Mb emitted from the second permanent magnet 12b returns to the second permanent magnet 12b. The magnetic flux Mb passing through the first permanent magnet 12a, the second permanent magnet 12b, the top yoke 16t, the outer yoke 16u and / or bottom yoke 16b is greater outside the yoke 16 compared to Figure 3A. The magnetic flux Mb thus outside the yoke 16 affects the workpiece W (not shown), which is a magnetic material, and the medium 30a of the display sheet 30 (not shown), which contains magnetic particles.

[0029] The display sheet 30 is provided on the outer surface of the top yoke 16t and the outer surface of the cover member 20 that covers the outer yoke 16u. Therefore, a strong magnetic flux Mb passes through the medium 30a of the display sheet 30. As the wavelength of the reflected light from the medium 30a becomes shorter, the color displayed on the display sheet 30 approaches green, blue, or purple. In addition, since a strong magnetic flux Mb passes through the workpiece W (not shown) located outside the outer yoke 16u, the workpiece W can be attracted to the magnetic gripper 10. Thus, by the color displayed on the display sheet 30, it is possible to determine at a glance whether or not the magnetic gripper 10 is in a state where it can attract the workpiece W.

[0030] The embodiments described above may be modified as follows. In the following modifications, explanations that overlap with the embodiments will be omitted.

[0031] (Variation 1) In the embodiment described above, the display sheet 30 is provided on the outer surface of the top yoke 16t and the outer surface of the cover member 20 that covers the outer yoke 16u, but is not limited to this. Figures 4A and 4B schematically show other configuration examples of the magnetic gripper 10, respectively. In the example shown in Figure 4A, the cover member 40 thinly covers the top yoke 16t. In that case, the display sheet 30 is provided on the outer surface of the cover member 40 that covers the top yoke 16t, rather than on the outer surface of the top yoke 16t.

[0032] In the example shown in Figure 4B, the cover member 20 does not completely cover the outer yoke 16u, leaving a portion of the outer yoke 16u exposed. Specifically, an example is shown where a predetermined range of the outer yoke 16u is exposed from the portion that contacts the top yoke 16t. In this case, the display sheet 30 is placed on the exposed outer surface of the outer yoke 16u, rather than on the outer surface of the cover member 20 that covers the outer yoke 16u.

[0033] In both the example shown in Figure 4A and Figure 4B, when a large amount of magnetic flux Mb is outside the yoke 16, a strong magnetic flux Mb passes through the medium 30a of the display sheet 30. Therefore, the color indicated by the display sheet 30 allows for a quick determination of whether or not the magnetic gripper 10 is in a state where it can attract the workpiece W.

[0034] (Modification 2) In the embodiment described above, the first permanent magnet 12a and the second permanent magnet 12b included in the permanent electromagnet 12 are arranged adjacent to each other. However, the first permanent magnet 12a and the second permanent magnet 12b do not have to be arranged adjacent to each other. For example, the first permanent magnet 12a and the multiple second permanent magnets 12b included in the permanent electromagnet 12 may be arranged such that the magnetization direction of the first permanent magnet 12a intersects with the respective magnetization directions of the second permanent magnets 12b.

[0035] When a voltage is applied to coil 14, a current flows through coil 14 in a predetermined direction, which reverses the magnetization direction of the second permanent magnet 12b. As a result, the magnet gripper 10 becomes unable to attract the magnetic workpiece W. In this case, most of the magnetic flux Mb emitted from the first permanent magnet 12a enters the second permanent magnet 12b, and most of the magnetic flux Mb emitted from the second permanent magnet 12b enters the first permanent magnet 12a. In other words, a large amount of magnetic flux Mb is confined within the permanent electromagnet 12 and the yoke 16. Therefore, almost no magnetic flux Mb escapes outside the yoke 16.

[0036] When a voltage is applied to coil 14 and a current flows through coil 14 in a predetermined direction, the magnetization direction of the second permanent magnet 12b can be reversed. As a result, the magnet gripper 10 becomes capable of attracting the magnetic workpiece W. In this case, there is almost no magnetic flux Mb entering the second permanent magnet 12b from the first permanent magnet 12a. There is also almost no magnetic flux Mb entering the first permanent magnet 12a from the second permanent magnet 12b.

[0037] Most of the magnetic flux Mb emitted from the first permanent magnet 12a returns to the first permanent magnet 12a. Most of the magnetic flux Mb emitted from the second permanent magnet 12b returns to the second permanent magnet 12b. Therefore, a large amount of magnetic flux Mb escapes outside the yoke 16. This magnetic flux Mb that escapes outside the yoke 16 affects the workpiece W, which is a magnetic material, and the medium 30a of the display sheet 30, which contains magnetic particles. In this case, the color indicated by the display sheet 30 allows for a quick determination of whether or not the magnetic gripper 10 is in a state where it can attract the workpiece W.

[0038] With regard to the embodiments and modifications described above, the following additional information is disclosed.

[0039] (Note 1) The magnetic gripper (10) of this disclosure is a magnetic gripper for attracting a workpiece (W), and comprises a permanent electromagnet (12) including a first permanent magnet (12a) and a second permanent magnet (12b), a coil (14) wound at least around the outer circumference of the second permanent magnet and capable of reversing the magnetization direction of the second permanent magnet when an electric current flows through it, a yoke (16) housing the permanent electromagnet inside, and a display sheet (30) having a medium (30a) made of a photocrystal of magnetic particles, the color of which changes according to the reversal of the magnetization direction of the second permanent magnet. With such a configuration, it is possible to determine whether or not the magnetic gripper is in a state where it can attract a workpiece.

[0040] (Note 2) The magnetic gripper described in Appendix 1, wherein the display sheet comprises the medium and a light-shielding sheet (30b) laminated on the medium, and the light-shielding sheet may have a window portion (30t) that transmits light incident on the medium and light reflected from the medium. With such a configuration, the color change shown by the display sheet becomes clearer.

[0041] (Note 3) The magnetic gripper is as described in Appendix 1 or 2, wherein the yoke includes a top yoke (16t) through which a magnetic flux (Mb) corresponding to the magnetic force generated by the permanent electromagnet passes, the workpiece is attracted toward the top yoke by the magnetic force, and the indicator sheet may be provided on the outer surface of the top yoke or on the outer surface of a cover member (40) covering the top yoke. With such a configuration, it is possible to determine at a glance whether the magnetic gripper is in a state where it can attract a workpiece by the color indicated by the indicator sheet.

[0042] (Note 4) The magnetic gripper is as described in Appendix 1 or 2, wherein the yoke includes a top yoke (16t) and an outer yoke (16u) through which a magnetic flux (Mb) corresponding to the magnetic force generated by the permanent electromagnet passes, the workpiece is attracted toward the top yoke by the magnetic force, the outer yoke extends in a direction intersecting the top yoke, and the indicator sheet may be provided on the outer surface of the outer yoke or on the outer surface of a cover member (20) covering the outer yoke. With such a configuration, it is possible to determine at a glance whether the magnetic gripper is in a state where it can attract a workpiece by the color indicated by the indicator sheet.

[0043] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of symbols]

[0044] 10...Magnetic gripper 12...Permanent electromagnet 14... Coil 16... Yoke 20, 40... Cover components; 30... Display sheet

Claims

1. A magnetic gripper for attracting a workpiece, A permanent electromagnet including a first permanent magnet and a second permanent magnet, A coil, which is wound at least around the outer circumference of the second permanent magnet and which can reverse the magnetization direction of the second permanent magnet when an electric current flows through it, A yoke housing the aforementioned permanent electromagnet on the inside, A display sheet having a medium made of photocrystals with magnetic particles, the color of which changes in accordance with the reversal of the magnetization direction of the second permanent magnet, A magnetic gripper equipped with a magnet.

2. A magnetic gripper according to claim 1, The display sheet comprises the medium and a light-shielding sheet laminated on the medium. The light-shielding sheet has a window portion that transmits light incident on the medium and light reflected from the medium, and is a magnetic gripper.

3. A magnetic gripper according to claim 1 or 2, The yoke includes a top yoke that passes a magnetic flux corresponding to the magnetic force generated by the permanent electromagnet, The workpiece is attracted toward the top yoke by the magnetic force, The display sheet is a magnetic gripper provided on the outer surface of the top yoke or the outer surface of the cover member covering the top yoke.

4. A magnetic gripper according to claim 1 or 2, The yoke includes a top yoke and an outer yoke that pass a magnetic flux corresponding to the magnetic force generated by the permanent electromagnet. The workpiece is attracted toward the top yoke by the magnetic force, The outer yoke extends in a direction intersecting the top yoke, The display sheet is a magnetic gripper provided on the outer surface of the outer yoke or the outer surface of the cover member covering the outer yoke.

Images