Holding device

Abstract

To provide a gripping device that is further reduced in size and weight than before.SOLUTION: The gripping device is provided with: a driving source (10); a planetary gear mechanism (22) that reduces a rotation speed of the driving source; and a carrier cam (240) in which a carrier part that transmits rotation output from a planetary gear (223) in the planetary gear mechanism is integrated with a cam part having cam grooves (241 and 242) that convert the rotation output from the carrier part to linear motion and transmit the linear motion to a pair of gripping parts (251 and 252). In the carrier cam, carrier pin holes (240ha and 240hb) through which a carrier pin (223j) protruding from the planetary gear is fixed to one surface (240a) at the driving source side are integrated with the cam grooves (241 and 242) through which cam followers (251c and 252c) protruding from the gripping parts are engaged with other surfaces (240b) of the gripping parts (251 and 252).SELECTED DRAWING: Figure 8

Description

Technical Field

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[0001] The present invention relates to a gripping device, and particularly to a motor-driven gripping device that grips a workpiece and performs positioning, length measurement, machining, etc. in automatic product assembly, automatic part machining, part transfer, inspection processes, and the like.

Background Art

[0002] Conventionally, for cost reduction and quality stabilization in production, automation of production lines has been promoted, and automation by robots has been introduced into many production lines due to its versatility.

[0003] In this type of robot, a gripping device for gripping a workpiece includes a gripping part having a plurality of claw parts and a driving part for driving the plurality of claw parts. The driving part and the gripping part are attached in series in this order to the tip of the arm in the robot (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0008] In the circumferential direction of the carrier cam, it is preferable that the carrier pin hole and the cam groove are formed at different positions from each other in the circumferential or radial direction of the carrier cam.

[0009] Preferably, the carrier pin hole is formed in a position that does not communicate with the cam groove.

[0010] Preferably, the carrier pin hole is formed between one cam groove and the other cam groove in the radial direction of the carrier cam. [Effects of the Invention]

[0011] According to the present invention, a gripping device that is even smaller and lighter than conventional devices can be realized. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing the overall external appearance of a gripping device according to one embodiment of the present invention. [Figure 2] This is a partial cross-sectional view showing a reduction gear and a hand portion of a gripping device according to one embodiment of the present invention, with a portion of them partially cut away. [Figure 3] This is a partial cross-sectional view showing the internal structure of the reduction gear and hand portion of a gripping device according to one embodiment of the present invention. [Figure 4] A perspective view showing the configuration of the carrier cam of the hand unit according to one embodiment of the present invention. [Figure 5] A three-view drawing showing the configuration of the carrier cam in the hand unit according to one embodiment of the present invention. [Figure 6] This is a partially cross-sectional view showing the configuration of a carrier cam according to one embodiment of the present invention. [Figure 7] This is a partially cross-sectional view showing the configuration of a carrier cam according to another embodiment of the present invention. [Figure 8] This is a plan view showing the configuration (1) of a carrier cam according to another embodiment of the present invention. [Figure 9] This is a plan view showing the configuration (2) of a carrier cam according to another embodiment of the present invention. [Modes for carrying out the invention]

[0013] (1) Outline of the embodiment First, a general overview of a typical embodiment of the invention disclosed in this application will be provided. In the following description, as an example, reference numerals on the drawings corresponding to the components of the invention are indicated in parentheses.

[0014] [1] A gripping device (1) according to a typical embodiment of the present invention comprises a drive source (10), a planetary gear mechanism (22) that reduces the rotational speed of the drive source (10), a carrier portion that transmits rotational output from the planetary gears (223) in the planetary gear mechanism (22), and a carrier cam (240) which is an integrated cam portion having cam grooves (241, 242) that convert the rotational output from the carrier portion into linear motion and transmit it to a pair of gripping portions (251, 252). The carrier cam (240) is characterized in that it comprises a carrier pin hole (240ha, 240hb) on one side (240a) on the drive source (10) side, to which a carrier pin (223j) protruding from the planetary gear (223) is fixed, and a cam groove (241, 242) on the other side (240b) on the gripping portion (251, 252) side, to which a cam follower (251c, 252c) protruding from the gripping portion (251, 252) is engaged.

[0015] 〔2〕In the gripping device (1), it is preferable that the carrier pin holes (240ha, 240hb) and the cam grooves (241, 242) are formed at different positions in the circumferential direction or the radial direction of the carrier cam (240).

[0016] 〔3〕In the gripping device (1), it is preferable that the carrier pin holes (240ha, 240hb) are formed at positions that do not communicate with the cam grooves (241, 242).

[0017] 〔4〕In the gripping device (1), it is preferable that the carrier pin holes (440ha, 440hb) are formed between one cam groove (441) and the other cam groove (442) in the radial direction of the carrier cam (440).

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely examples, and various forms can be adopted within the scope of the present invention.

[0019] <Overall configuration of the gripping device> First, the overall configuration of the gripping device according to an embodiment of the present invention will be described based on FIG. 1. FIG. 1 is a perspective view showing the overall external configuration of the gripping device in the assembled state. FIG. 2 is a partial cross-sectional view in which the reducer and the hand portion of the gripping device are partially cut. FIG. 3 is a partial cross-sectional view showing the internal structure of the reducer and the hand portion. FIG. 4 is a perspective view showing the configuration of the carrier cam of the hand portion according to an embodiment of the present invention. FIG. 5 is a three-view drawing showing the configuration of the carrier cam in the hand portion according to an embodiment of the present invention. FIG. 6 is a partially cut cross-sectional view showing the configuration of the carrier cam according to an embodiment of the present invention. FIG. 7 is a partially cut cross-sectional view showing the configuration of the carrier cam in another embodiment.

[0020] For the sake of explanation, in the diagram, arrows ab and b are defined as the up and down directions, with arrow a being the upper side and arrow b being the lower side. Also, arrows cd perpendicular to arrows ab (up and down directions) are defined as the horizontal direction, with arrow c being the left side and arrow d being the right side. Furthermore, arrows ef perpendicular to both arrows ab (up and down directions) and arrows cd (horizontal directions) are defined as the longitudinal or depth direction, with arrow e being the front side and arrow f being the back side. Note that these directions are not related to the direction of gravity and change according to the orientation of the robot device to which the gripping device 1 is attached.

[0021] As shown in Figures 1 to 7, the gripping device 1 comprises a motor 10 as a drive source, a reduction gear 20 attached to the motor 10, and a hand cover 30 attached to the reduction gear 20.

[0022] The motor 10 has a drive source inside its casing, which is, for example, an AC servo motor with an output of about 100W to 200W, and the output shaft 10a of the drive source protrudes from the casing. This motor 100 may be any other type of motor as long as position control and torque control are possible.

[0023] A reduction gear 20 is attached to the motor 10. The reduction gear 20 has a planetary gear mechanism 22 inside and reduces the rotation of the output shaft 10a of the motor 10 to a predetermined speed before transmitting it to the upper hand base 251 and the lower hand base 252, which will be described later as gripping parts.

[0024] The planetary gear mechanism 22 includes an internal gear 221 formed on the inner circumference side of the casing 21 of the reduction gear 20, a sun gear 222 attached to the output shaft 10a of the motor 10, and two planetary gears 223 that engage with both the sun gear 222 and the internal gear 221, and revolve around the sun gear 222 while rotating together with the sun gear 222. However, the planetary gear mechanism 22 is not limited to this configuration, and may have a configuration with three or four planetary gears 223. Furthermore, such planetary gear mechanisms 22 may be connected in series in two or more stages (for example, three stages, four stages, etc.).

[0025] The internal gear 221 is integrally formed with a portion of the inner circumferential surface of the casing 21 and is fixed integrally with the casing 21 without relative rotation with respect to the sun gear 222 and planetary gears 223.

[0026] Here, the internal gear 221 does not necessarily have to be integrated with the casing 21; the internal gear 221 and the casing 21 may be constructed as separate parts and fixed together. For example, the internal gear 221 may be made of heat-treated steel, and the casing 21 may be made of aluminum treated for rust prevention and weight reduction.

[0027] Furthermore, in the casing 21, a spacer 231 and a bearing 232 are installed between the motor 10 and the internal gear 221 on its inner circumferential surface.

[0028] The sun gear 222 has a through hole 222h with a keyway in its center, and is fixed integrally with the output shaft 10a of the motor 10 with a key 10ak fitted into it.

[0029] A cylindrical planetary gear support portion 233, which supports the rotation axis of the planetary gear 223, is fixed to the inner ring of the bearing 232. The planetary gear support portion 233 has a through hole 233h in the center that is large enough to accommodate the sun gear 222.

[0030] Furthermore, the shafts of two planetary gears 223 are integrally fixed around the outer circumference of the through hole 233h in the planetary gear support portion 233. In this case, the two planetary gears 223 are positioned opposite each other at 180-degree angles apart.

[0031] In other words, the planetary gear 223 can rotate together with the planetary gear support 233 as the sun gear 222 rotates. Furthermore, inside the planetary gear 223, a bearing 223g is integrally attached to the shaft of the planetary gear 223, and the planetary gear 223 rotates on its own axis and revolves around the sun gear 222 via the bearing 223g.

[0032] A planetary carrier 240 is integrally fixed to the carrier pin 223j at one end of the planetary gear 223 on the front side (direction of arrow e), i.e., the side facing the hand cover 30. Therefore, as the two planetary gears 223 revolve around the axis of rotation of the sun gear 222 in conjunction with the rotation of the sun gear 222, the planetary carrier 240 also rotates around the axis of rotation of the sun gear 222.

[0033] The planetary carrier 240 is rotatably supported on the casing 21 via bearings 239. In this case, the outer ring of bearing 239 is fixed to the inner circumferential surface of the casing 21, and the inner ring of bearing 239 is fixed integrally with the planetary carrier 240.

[0034] As shown in Figures 3 to 5, one side of the planetary carrier 240 facing the motor 10 is provided with closed-end carrier pin holes 240ha and 240hb (not shown in Figure 3), into which the tips of the carrier pins 223j of the two planetary gears 223 are fitted and fixed together. However, the carrier pin holes 240ha and 240hb do not necessarily have to be closed-end as described above; they may be through-holes as long as the planetary gears 223 and the planetary carrier 240 can be fixed together.

[0035] In other words, the tips of the carrier pins 223j of the two planetary gears 223 are integrally fixed to the carrier pin holes 240ha and 240hb of the planetary carrier 240, so that the planetary carrier 240 can rotate together with the revolution of the two planetary gears 223.

[0036] Furthermore, the planetary carrier 240 has two arc-shaped grooves, cam grooves 241 and 242, formed on the hand cover 30 side, opposite to the motor 10 side where the carrier pin 223j of the planetary gear 223 is fixed.

[0037] The two cam grooves 241 and 242 are arc-shaped grooves into which the cam follower 251c of the upper hand base 251 and the cam follower 252c of the lower hand base 252 engage, with the cam follower 251c of the upper hand base 251 and the cam follower 252c of the lower hand base 252, which are provided to be movable in the vertical direction (arrow ab direction).

[0038] In this case, the two cam grooves 241 and 242 are all formed from Archimedean spiral curves with the same curvature and groove length. Here, since the cam curves of cam grooves 241 and 242 are formed by Archimedean spirals, cam grooves 241 and 242 are perfectly identical in shape and point-symmetric with respect to the center of the planetary carrier 240.

[0039] The cam grooves 241 and 242 convert the rotational output from the planetary carrier 240 into linear motion and transmit it to the upper hand base 251 and lower hand base 252, which form a pair of gripping parts. The cam grooves 241 and 242 are bottomed grooves with a depth to which the cam followers 251c and 252c engage, but they do not penetrate the planetary carrier 240.

[0040] Even if the cam grooves 241 and 242 penetrate the planetary carrier 240, the cam follower 251c of the upper hand base 251 and the cam follower 252c of the lower hand base 252 can engage with them, thus the cam grooves still function. However, this is not practical because the lubricant of the reducer 20 would leak out through these penetrating cam grooves. In other words, it is preferable that the cam grooves 241 and 242 of the planetary carrier 240 are closed grooves.

[0041] Thus, the planetary carrier 240 has carrier pin holes 240ha and 240hb on one side facing the motor 10, into which the tips of the carrier pins 223j of the two planetary gears 223 are fitted, and on the other side facing the hand cover 30, there are two cam grooves 241 and 242.

[0042] In other words, the planetary carrier 240 is integrated to function not only as the carrier portion of the planetary gear 223, but also as a cam portion that drives the upper hand base 251 and the lower hand base 252 in the vertical direction. Therefore, since the planetary carrier 240 has both carrier and cam functions, it will be referred to as the "carrier cam 240" below.

[0043] As shown in Figure 5, two cam grooves 241 and 242 are formed on the other surface 240b of the carrier cam 240 so as to be point-symmetrical with respect to the center of the output shaft 10a. Additionally, two carrier pin holes 240ha and 240hb are formed on one surface 240a of the carrier cam 240 at positions that do not overlap with the two cam grooves 241 in the circumferential direction.

[0044] In other words, as shown in Figure 6, in the carrier cam 240, the two cam grooves 241 and 242 and the two carrier pin holes 240ha and 240hb are formed alternately, so that its thickness 240s can be made as thin as possible. To put it another way, the two carrier pin holes 240ha and 240hb are formed in positions that do not communicate with each other.

[0045] The upper hand base 251 has a gripping block 251b integrally fixed to the end of the cam follower 251c on the hand cover 30 side. Similarly to the upper hand base 251, the lower hand base 252 also has a gripping block 252b integrally fixed to the end of the cam follower 252c on the hand cover 30 side. The upper hand base 251 and the lower hand base 252 are gripping parts that grip objects to be gripped, such as workpieces.

[0046] These gripping blocks 251b and 252b are the parts to which arms for gripping a predetermined workpiece or jaws for clamping a predetermined workpiece are attached. Therefore, the upper hand base 251 and the lower hand base 252 move closer to each other to clamp and grasp an object to be gripped, such as a workpiece, and the gripped object can be released when the upper hand base 251 and the lower hand base 252 move further apart from each other.

[0047] The hand cover 30 is a roughly rectangular lid that covers the carrier cam 240, while exposing the gripping block 251b of the upper hand base 251 and the gripping block 252b of the lower hand portion 252, and is attached to the casing 21.

[0048] The hand cover 30 has two columnar guide parts 301 and 302 that guide the gripping blocks 251b and 252b in the vertical direction when the two gripping blocks 251b and 252b move in the vertical direction.

[0049] Furthermore, the hand cover 30 has elongated holes 303 and 304, which are through holes formed to extend vertically, through which the cam follower 251c of the upper hand base 251 and the cam follower 252c of the lower hand base 252 are inserted, respectively, between the two guide portions 301 and 302.

[0050] In the above configuration, the gripping device 1 can rotate the carrier cam 240 clockwise via the planetary gear mechanism 22 by rotating the output shaft 10a of the motor 10 in a clockwise direction (CW). At this time, the upper hand base 251 and the lower hand base 252, through which the cam followers 251c and 252c are inserted into the cam grooves 241 and 242 of the carrier cam 240, move closer to each other in the vertical direction along the elongated holes 303 and 304.

[0051] Conversely, the gripping device 1 can rotate the carrier cam 240 in a counterclockwise direction via the planetary gear mechanism 22 by rotating the output shaft 10a of the motor 10 in a counterclockwise direction (CCW). At this time, the upper hand base 251 and the lower hand base 252, through which the cam followers 251c and 252c are inserted in the cam grooves 241 and 242 of the carrier cam 240, move away from each other in the vertical direction along the elongated holes 303 and 304.

[0052] In this way, in the gripping device 1, the carrier cam 240, which is rotated by two planetary gears 223, is integrated so that it also serves as a cam that moves the upper hand base 251 and the lower hand base 252 in the vertical direction. This allows the gripping device 1 to be shortened in the longitudinal direction (arrow ef direction) and made more compact overall.

[0053] <Other Embodiments> In the above-described embodiment, two cam grooves 241 and 242 are formed on the other surface 240b of the carrier cam 240, and two carrier pin holes 240ha and 240hb are formed on one surface 240a of the carrier cam 240 at positions that do not overlap with the two cam grooves 241 in the circumferential direction.

[0054] However, the present invention is not limited to this, and as shown in Figure 7, the carrier cam 340 may have two cam grooves 241 and 242 formed on the other surface 340b, and two carrier pin holes 240ha and 240hb formed on one surface 340a of the carrier cam 240 at positions that overlap with the two cam grooves 241 in the circumferential direction. In short, the carrier cam 340 only needs to have at least both carrier and cam functions.

[0055] Furthermore, in the above-described embodiment, two cam grooves 241 and 242 are formed on the other surface 240b of the carrier cam 240, and two carrier pin holes 240ha and 240hb are formed on one surface 240a of the carrier cam 240 at positions that do not overlap with the two cam grooves 241 in the circumferential direction. However, the present invention is not limited to this, and the two carrier pin holes 240ha and 240hb may be formed at positions that do not overlap in the radial direction as well as the circumferential direction. Figure 8 is a plan view showing the configuration (1) of a carrier cam according to another embodiment of the present invention. Figure 9 is a plan view showing the configuration (2) of a carrier cam according to another embodiment of the present invention.

[0056] For example, as shown in Figure 8, the carrier cam 440 has two cam grooves 441 and 442. Since the cam curves of the cam grooves 441 and 442 are formed by the Archimedes spiral, the distance between the cam grooves 441 and 442 in the radial direction is constant. Therefore, carrier pin holes 440ha and 440hb, into which the tip of the carrier pin 223j of the planetary gear 223 is fitted, can be formed between the cam grooves 441 and 442 in the radial direction. In this case, the carrier cam 440 can be made smaller in the radial direction. Note that the carrier pin holes 440ha and 440hb may be through holes.

[0057] Here, the speed ratio of the reduction gear 20 using a planetary gear mechanism is determined by the number of teeth of the sun gear 222 and the internal gear 221. In other words, the distance between the centers of the sun gear 222 and the planetary gear 223 changes according to the number of teeth. Therefore, if the distance between the cam grooves is larger than the diameter of the tip of the carrier pin 223j in the planetary gear 223, it is possible to accommodate multiple speed ratios even if the displacement angle of the curves due to the cam grooves 441 and 442 is large (for example, 180 degrees or more).

[0058] Furthermore, as shown in Figure 9, for example, the carrier cam 540 has three cam grooves 541, 542, and 543. In this case as well, carrier pin holes 540ha, 540hb, and 540hc for which the tip of the carrier pin 223j of the planetary gear 223 is fitted can be formed radially between cam groove 541 and cam groove 542, between cam groove 542 and cam groove 543, and between cam groove 543 and cam groove 541. In this case as well, the carrier cam 540 can be made smaller radially. Note that the carrier pin holes 540ha and 540hb may be through holes.

[0059] The embodiments of the present invention are not limited to the gripping device 1, but include all aspects included in the concept and claims of the present invention. Furthermore, each component may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. For example, the shape, material, arrangement, size, etc., of each component in the embodiments may be appropriately changed depending on the specific specifications of the present invention. [Explanation of Symbols]

[0060] 1...Gripping device, 10...Motor, 10a...Output shaft, 20...Reduction gear, 21...Casing, 22...Planetary gear mechanism, 30...Hand cover, 221...Internal gear, 222...Sun gear, 223...Planetary gear, 231...Spacer, 232,239...Bearing, 233...Planetary gear support, 240...Carrier cam (planetary carrier), 240ha, 240hb...Carrier pin hole, 241,242...Cam groove, 251...Upper hand base, 252...Lower hand base, 251c, 252c...Cam follower, 251b,252b...Gripping block, 301,302...Guide part, 303,304...Slotted hole.

Claims

1. Power source and A planetary gear mechanism for reducing the rotational speed of the aforementioned drive source, A carrier cam is formed by integrating a carrier portion that transmits rotational output from the planetary gears in the planetary gear mechanism, and a cam portion having a cam groove that converts the rotational output from the carrier portion into linear motion by a guide portion that guides a pair of gripping portions in a predetermined straight-line direction and transmits it to the pair of gripping portions. Equipped with, The carrier cam has a carrier pin hole on one side facing the drive source, into which a carrier pin protruding from the planetary gear is fixed, and a cam groove on the other side facing the gripping portion, into which a cam follower protruding from the gripping portion is engaged. The cam groove is formed in a curved shape such that it approaches the axis of rotation as it is directed in either direction in the circumferential direction, relative to the arc of rotation of the carrier cam. In the circumferential direction of the carrier cam, the carrier pin hole and the cam groove are formed at different positions from each other in the circumferential or radial direction of the carrier cam. A gripping device characterized by the following features.

2. Power source and A planetary gear mechanism for reducing the rotational speed of the aforementioned drive source, A carrier cam is formed by integrating a carrier portion that transmits rotational output from the planetary gears in the planetary gear mechanism, and a cam portion having a cam groove that converts the rotational output from the carrier portion into linear motion by a guide portion that guides a pair of gripping portions in a predetermined straight-line direction and transmits it to the pair of gripping portions. Equipped with, The carrier cam has a carrier pin hole on one side facing the drive source, into which a carrier pin protruding from the planetary gear is fixed, and a cam groove on the other side facing the gripping portion, into which a cam follower protruding from the gripping portion is engaged. The cam groove is formed in a curved shape such that it approaches the axis of rotation as it is directed in either direction in the circumferential direction, relative to the arc of rotation of the carrier cam. The carrier pin hole is formed in a position that does not communicate with the cam groove. A gripping device characterized by the following features.

3. The carrier pin hole is formed between one cam groove and the other cam groove in the radial direction of the carrier cam. The gripping device according to feature 2.

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