WO2021044835A1

WO2021044835A1 - Workpiece gripping device

Info

Publication number: WO2021044835A1
Application number: PCT/JP2020/031047
Authority: WO
Inventors: 康彦可知
Original assignee: 康彦可知
Priority date: 2019-09-03
Filing date: 2020-08-18
Publication date: 2021-03-11
Also published as: JP2021037574A; JP7107508B2

Abstract

[Problem] To provide a workpiece gripping device for effectively utilizing an industrial robot in view of the workplace environment and the object being worked in the field by, for example, casting, forging, and thermal processing. [Solution] A workpiece gripping device in which an auxiliary finger 5 is added to a gripper 4 with which a hand portion 2 at the tip-end of a robot arm is equipped. The auxiliary finger is in a straight shape in a stand-by state to facilitate approach thereof to a target workpiece, and is formed in a generally rigid arc-like shape in a stage for gripping the workpiece as a drawing device 6 in the hand pulls a tip-end block via a drawing tool penetrating through each block. Finally, grippers 3, 4 are closed to support the workpiece from the lower surface side and the side surfaces thereof, thus making it possible to stably grip even a heavy workpiece.

Description

Work gripping device

The present invention relates to a work gripping device provided on a hand portion at the tip of an industrial robot arm.

Industrial robots are widely used in large-scale mass production factories such as the automobile industry and semiconductor industry, and contribute significantly to improving productivity, quality, and labor saving. Moreover, in many developed countries, it tends to be difficult to secure a labor force due to the effects of aging and population decline, and further expansion of the fields in which robots can be used is expected as one of the effective measures. In order to effectively utilize industrial robots, the most important requirement is to develop a work gripping device that can stably hold the target work in each work environment and handle it reliably according to the purpose of the work. .. In a large-scale mass production factory as described above, it is easy to summarize the specifications of the workpieces to be handled and the contents of processing in each stage, and the workpiece gripping device can be customized according to the application, so the conditions for introducing an industrial robot are in place. it is conceivable that.

Work sites such as casting, forging, and heat treatment have a high physical load because they handle heavy semi-finished products and products, and there are high heat, noise, and dangerous work, and it is difficult to keep the work environment clean. It is easy to be called a 3K workplace. Therefore, although it has been difficult to secure a stable labor force, the reason why the introduction of industrial robots has not been active is that a work gripping device that can meet the following conditions has not been established. (1) There are various varieties, shapes and sizes, and each of them is not quantitatively organized and is often mixed. (2) Since the workpieces are not always organized on the table and are often placed in the tray in a mixed manner, it is difficult to pick up the workpieces with a large-scale gripping device. (3) Mainly semi-finished products and finished products of metals such as steel, each of which has a relatively large weight. (4) It is used under conditions such as a work environment with a lot of oxide scale and dust, and a high temperature of the work. (5) Sometimes there is rough handling and durability is required.

There is a device for gripping a work by equipping the hand portion with a jig called a gripper that opens and closes in a horizontal plane. This is an effective method when there is little change in the shape and dimensions of the target work and a portion to be sandwiched by the jig can be stably secured. However, since the weight of the work is supported only by the frictional force between the jig and the surface of the work, a tightening force several times the weight of the work is required. Therefore, such a method is suitable for handling a relatively light workpiece. (See Patent Document 1)

If the shape of the work has a specific element suitable for gripping, a simpler method can be selected. For example, if there is always a recess of a certain size, a special fixing claw is provided at the tip of the gripper, if there is a flat part of a certain area, it is sucked with a vacuum pad, and an opening of a predetermined size is opened in the center. If there is a portion, there is a method of inserting a jig into the hole to expand and grip the portion. Both methods are suitable for workpieces with a relatively light weight. (See Patent Document 2)

When the material of the work is a magnetic material such as steel, there is a method of equipping the hand portion with an electromagnet and gripping the work by its suction force. According to the adsorption of magnetic force, the work can be gripped without being affected by the shape and the placed state, so that it is highly versatile and efficient. In addition, depending on the magnetic force, it can handle a large weight of several tons or more. However, the problem is that residual magnetism remains around the work that has been attracted, which makes it difficult to handle and arc weld smoothly in the subsequent processes, and causes adsorption of magnetic powder and malfunction of the sensor in terms of work and quality control. Various troubles occur. Therefore, this method is applied when the residual magnetism can be reduced by subsequently raising the temperature of the work to the magnetic transformation temperature or passing through a demagnetization system. (See Patent Document 3)

As a device for stably gripping workpieces having various shapes and dimensions, a gripping device having a three to five finger-shaped articulated mechanism like a human hand has also been developed. It is composed of a refraction mechanism that gently fits the outer shape of an object and an activator that manipulates them. Not only does it have a high degree of freedom in shape, but it also has the characteristic of being able to handle soft materials such as strawberries. However, at present, the weight that can be handled is limited to about 500 ml PET bottles, and since it is equipped with a large number of actuators and sensors that control them, it is equipped with a high temperature atmosphere, an environment with a lot of oxidation scale and dust, and sometimes a shock. It is a device that is difficult to handle with rough handling. (See Non-Patent Document 1)

JP-A-2004-05032112 Gripping control method and gripping device for robot hand

Japanese Patent Application Laid-Open No. 06-226673 Robot Hand

Japanese Patent Application Laid-Open No. 4-229605 Control method and device of adsorption electromagnet and control electromagnet

(B) The problem to be solved is that industrial robots cannot be fully utilized for handling relatively heavy works at sites such as casting, forging, and heat treatment. (B) The main reason for this was that a work gripping device suitable for the work environment and objects at the site had not been developed.

The present invention is a work gripping device provided in the hand portion at the tip of an industrial robot arm, which targets semi-finished products or finished products, each of which is relatively heavy in weight in an environment with a large amount of oxide scale and dust, and is arranged in a stand. It has a function to grip the work so that it can be handled stably even if it is placed in a mixed manner as well as when it is placed, and it does not depend on the method that uses the attractive force of the electromagnet. ..

An auxiliary finger is added to the gripper that opens and closes in the horizontal direction, which is generally provided in the hand part, and the whole is curved in an arc shape to become rigid so that it follows the lower surface of the work, and the tip is on the lower surface side of the work. It is a work gripping device that can support the weight from the lower surface side by entering.

The auxiliary finger is composed of one or more intermediate blocks and a tip block, and the block can be made of any material or manufacturing method as long as the necessary functions can be obtained. When viewed from the side, each block has a trapezoidal shape with a short side in contact with the work and a long side not in contact with the work, and is connected from the gripper to the tip block by hinges at the upper and lower ends on the long side. .. There is a hollow portion that penetrates from the gripper to the tip block via the intermediate block, and one traction tool penetrates them and is connected from the traction device in the hand to the pin of the tip block.

The traction tool means a chain, wire or rope, and the material and dimensions do not matter as long as the specifications can withstand the required tension. The traction device applies tension to the above-mentioned traction tool, and any device that can control the tension and traction amount required to maintain the curved shape of the auxiliary finger against the weight when gripping the work. , Warm wheels, rotary encoders, servo motors, power cylinders, etc., in any combination.

When gripping the work, the tip block is pulled by applying tension to the traction tool with a traction device. As a result, the short side of each block that has been opened is brought into close contact with each other in sequence, and the auxiliary finger becomes an arc shape with a concave side in contact with the work when viewed from the side surface, and the whole becomes rigid. The gripper is finally closed after the auxiliary fingers have secured the required rigidity.

The traction tool of the auxiliary finger is relaxed without applying strong tension except when gripping, that is, in the standby state, the short side side of all blocks is opened and the whole hangs down by its own weight, but the spring provided on the connecting hinge Due to the mechanism and the angle stopper, all blocks have the function of aligning the long side in a straight line and holding the state.

Auxiliary fingers are provided on at least two opposing grippers among the grippers provided on the hand portion. When a plurality of grippers are divided into functions for long sides and short sides so as to correspond to the projected shape of the work, it is effective to provide auxiliary fingers on the opposing grippers for the short sides.

When making the auxiliary finger compatible with a workpiece smaller than the size assumed in the design, a wedge-shaped shim is fitted in the opening on the short side of the intermediate block to reduce the overall amount of curvature when gripping. It can be dealt with.

After selecting the workpiece to be gripped and determining the gripping procedure based on the information from the visual sensor, the robot arm adjusts the orientation and height of the hand, and the gripper mechanism adjusts the opening, and the auxiliary finger in the standby state. Close to both sides of the work. The adjustment in the height direction required in the process of changing the auxiliary finger from the standby state to the arc shape is controlled by the robot arm. The gripping of the work is completed by closing all the grippers after the auxiliary fingers form an arc shape and secure the rigidity.

In the work gripping device of the present invention, an auxiliary finger is connected to a gripper provided on the hand portion at the tip of the robot arm, which forms an arc shape to maintain rigidity. It can be inserted on the lower surface side, and then the gripper can be finally closed. As a result, the weight is not only supported by the frictional force of the side surface by the gripper, but also from the lower surface side along the work, so unstable movement such as slipping and rocking is prevented even for various heavy works. It can be gripped in a stable state.

The auxiliary fingers are not integrated, but have a structure in which a large number of blocks are connected by hinges. As a result, the required space before and after the finger in the standby state, that is, when not gripping, can be suppressed to be significantly smaller than in the case of integration, so that the work can be easily picked up even when the gap between the works is narrow.

The mechanism for forming the curved shape of the auxiliary finger is simple, and the finger part does not require a complicated link mechanism, pneumatic or hydraulic cylinders, or even a large number of sensors. Therefore, since the whole can be realized in a slim shape, it is easy to bring the auxiliary fingers close to each other even when the workpieces are miscellaneously placed and the gap between the workpieces is narrow, and the workpiece is placed on a dedicated stand when introducing the robot. There is no need to align the robots, which saves time and effort and does not squeeze the storage space.

The activator that curves the auxiliary finger in an arc shape is mainly a traction device, and can be installed in the hand remote from the work. Therefore, since the finger portion close to the work does not have a delicate mechanism or a large number of sensors, it is not easily broken by an impact and can easily withstand disturbances such as radiant heat of the work. In addition, it is not easily affected by the oxide scale and a dirty environment with a lot of dust, and the simple mechanism makes it easy to clean when it gets dirty and easy to maintain in the event of a failure.

The work gripping device is effective for stably gripping a work having a diameter equal to or larger than the diameter of the arc formed by the two opposing auxiliary fingers. When handling a workpiece smaller than that, it is possible to reduce the radius formed by applying a wedge-shaped shim between the blocks.

If the work gripping device is changed according to the size, weight, arrangement, etc. of the target work, replace it with another hand. The change of actuator connection required at that time is completed only by the electric system, and it is quick and convenient because there is no need to change the connection of hydraulic or pneumatic pipes.

Since it is not an adsorption method using an electromagnet, no residual magnetism remains on the workpiece being handled.

FIG. 1 is an operation explanatory view of a work gripping device using an auxiliary finger. FIG. 2 is an operation explanatory view of a finger of a type in which an arc-shaped hook rotates around a fulcrum. FIG. 3 is an operation explanatory view of a type of finger in which an arcuate hook that is divided into multiple parts and connected is rotated around a fulcrum. FIG. 4 is a side view showing a gripping state of the auxiliary fingers (concentric circle type). FIG. 5 is a side view showing the standby state of the auxiliary fingers (concentric circle type). FIG. 6 is a side view showing a gripping state of the auxiliary finger (concentric circle type). FIG. 7 is a side view showing a standby state of the auxiliary finger (concentric circle type). FIG. 8 is a side view showing a state in which a wedge-shaped shim is applied between blocks and gripped.

Embodiments of the invention will be described with reference to the drawings based on the examples. FIG. 1 is an operation explanatory view of a work gripping device using the auxiliary finger of the present invention. In (1), various workpieces placed in the yard are recognized by a visual sensor, selection of the target workpiece 1 to be gripped, and analysis for accurately grasping the workpiece (overall shape of the workpiece, position of the center of gravity, horizontal direction). Tilt, tilt in the vertical plane, gripping procedure, etc.). (2) shows a stage in which the robot arm adjusts the height and controls the angle of the hand 2 at the tip so that it can be easily grasped and approaches the target work 1. The illustrated hand 2 has two long-side grippers 3 and two short-side grippers 4 that open and close in the horizontal direction, and the short-side gripper is provided with an auxiliary finger 5. At this stage, both grippers are approaching the work but have not yet pinched it.

(3) shows the operating state of the auxiliary finger 5 by paying attention only to the gripper for the short side. In (3) -1 and (3) -2, the traction tool 15 (roller chain in this case) penetrating the inside of the auxiliary finger 5 is towed by the hoisting mechanism 6 while lowering the height of the hand 2 with the robot arm to assist. The steps until the entire finger is formed into an arc shape are shown. (3) -3 is a stage in which the work is subsequently restrained by the opening / closing mechanism of the short side gripper 4. (3) -4 indicates a stage in which the opening / closing mechanism of the long side gripper 3 is operated to complete the gripping of the work 1.

FIG. 2 is an operation explanatory view of an example in which an arc-shaped auxiliary finger is embodied. An auxiliary finger of the type that allows the tip to enter the lower surface of the work by rotating the arc-shaped hook connected to the fixed block by a hinge by 90 degrees in the work direction when gripping the work, and can support the weight of the work from the lower surface as well. There are advantages. However, in the standby state, the rear part of the hook protrudes more than the vertical line, so that it is difficult to insert the auxiliary finger when the distance between the workpieces is narrow. If it is attempted to reduce the overhang so that it can be easily inserted, the radius of the arc of the finger must be reduced, so that the effect of stably gripping the work cannot be sufficiently obtained. The same applies to the following figures, but here only the auxiliary fingers on one side are shown, and the opposing auxiliary fingers arranged symmetrically are omitted.

FIG. 3 is an operation explanatory view of an auxiliary finger of a type in which an arcuate hook that rotates around a fulcrum as shown in FIG. 2 is divided into multiple parts (two parts in the figure) instead of being integrated. The shape when the work is gripped is the same as that in FIG. 2, but in the standby state, the number of hooks can be significantly reduced as compared with the case where the rearward overhang is not divided. Therefore, even when the space between the workpieces is small, the auxiliary finger can be easily inserted and the workpiece can be easily gripped. However, in order to take advantage of these advantages, a simple actuator has the function of holding the multi-divided hooks in a straight line in the standby state and forming a rigid integrated arc-shaped hook with many hooks when gripping the work. And it needs to be realized by the mechanism.

FIG. 4 and subsequent views are side views of the auxiliary fingers embodying the type in which the arcuate hook is divided into many parts. FIG. 4 shows an example in which the arc-shaped hook is divided into three intermediate blocks 11 and one tip block 12, and all the blocks form an integral arc-shaped hook having rigidity with the short side inside. However, it shows the state of gripping the work. The finger tip block is provided with an acute-angled guide so that it can easily enter the lower part of the work. In the example shown here, the envelopes on the outer surface side opposite to the inner surface side in contact with the work of the block group when the finger is viewed from the side are concentric circles, and the thickness seen from the side surface from the first block to the tip block is It is almost constant.

The auxiliary fingers are continuous with the gripper 10, and a plurality of (three in this case) intermediate blocks 11 and tip blocks 12 are connected by hinges 13. In the gripped state of the work, tension is applied to the attracting tool 15 (roller chain in the figure) that penetrates each block and is connected to the pin 14 of the tip block, and the short side side of each block that was open during standby is in close contact. , Form an integral arc-shaped hook with rigidity as a whole. The necessary conditions for this are that the block has a short side and a long side, that the long side is connected by a hinge, and that the block has a surface that is attracted and brought into close contact with a traction tool. It does not have to be trapezoidal, and may be E-shaped.

FIG. 5 is a side view of the standby state of the auxiliary finger. In the standby state, the inspection tool 15 relaxes and the intermediate block 11 and the tip block 12 hang down in the vertical direction due to their own weight, but the long side side of each block is aligned linearly by the spring and angle stopper equipped on the hinge 13. It is controlled. Sections AA show a cross section of the intermediate block 11, and cross sections BB show a cross section of the tip block 12. The tip block is provided with a pin 14 for connecting the traction tool.

The cross-sectional view of the embodiment is rectangular as a whole, but the necessary condition for satisfying the function is that the side in contact with the work has a necessary area suitable for gripping, and the opposite side can be equipped with a hinge. The space through which the traction tool penetrates is secured, and the strength required for gripping the work is secured as a whole. If these conditions are met, the cross section as a whole may be inverted Δ-shaped or T-shaped. I do not care. In the figure, the wall thickness on both sides of the block is reduced as an example of a device for reducing the total weight of the auxiliary fingers.

FIG. 6 is a side view in which the auxiliary finger grips the work, but unlike FIG. 4, the envelope of the arc on the inner surface side and the opposite side in contact with the work of the block group is an example of a concentric circle type. The moment for supporting the weight of the work with the auxiliary fingers is secured, but if it is insufficient, the phenomenon that the lower surface of the fixed block and the upper surface of the uppermost intermediate block cannot be secured first appears. If the block shape of the auxiliary finger is a concentric circle type, the arm length from the top hinge to the traction tool can be longer than in the case of the concentric circle type, so the tension applied to the traction tool required to support the work weight can be reduced. There are advantages.

FIG. 7 is a side view of the standby state of the auxiliary finger of FIG. Since it is a concentric circle type, the thickness gradually decreases from the upper end of the intermediate block to the tip block. Sections AA, BB, and CC show such a situation. Other explanations are similar to those in Fig. 5, so they are omitted here.

FIG. 8 is a side view showing a state in which a wedge-shaped shim is installed between the fixed block and the uppermost intermediate block to grip the work. This figure is an example of an auxiliary finger designed assuming that the short side of the work is 200 mm or more. For example, by applying a wedge-shaped shim of about 13 degrees as shown in the figure, the work can be gripped stably. The range can be expanded to 140 mm or more. Further, if the same wedge-shaped shim is applied between the next blocks, the range of the work that can be stably gripped can be expanded to 90 mm or more.

1 work 2 hand part 3 long side gripper 4 short side gripper 5 auxiliary finger 6 traction device 10 gripper 11 intermediate block 12 tip block 13 hinge 14 pin 15 traction tool 20 wedge type shim

Claims

It is a device with auxiliary fingers added to the gripper mechanism provided in the hand part at the tip of the arm of an industrial robot. It is composed of multiple hollow blocks, and when each block is viewed from the side, the side in contact with the work is It has a trapezoidal shape with a short opposite side and a long side, and they are connected by a hinge only at the upper and lower ends on the long side. By applying tension to the traction tool that penetrates the inside of the gripper and block and reaches the block at the tip, the short side is pulled and the entire shape is formed into an arc shape with the required rigidity, thereby forming the lower surface side of the work. A work gripping device that features a function that allows it to enter and be supported from below.
When the plurality of blocks constituting the auxiliary finger rotate in the direction of gripping the work, that is, in the direction in which the gaps on the short sides are in close contact with each other and formed in an arc shape due to the traction tension, the angles are freely changed by the connecting hinges. However, when the pulling tension relaxes and the finger shifts to the standby state, the block group is returned to a straight line by the spring mechanism, and the long side side of each block is aligned in a straight line by the angle stopper provided on the hinge. The work gripping device according to claim 1, wherein the work gripping device has a function of being able to maintain the state of the work.