RU2813430C1 - Stack gripper - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention relates to gripping devices, in particular to devices for gripping stacks. Device for gripping stacks comprises a power drive and a gripping unit. At the same time, power drive is configured to control the gripping unit so as to clamp the stack. Gripping unit comprises two gripping elements comprising a plurality of fingers, which are parallel plates made with possibility of rotation on axis on gripping element when gripping stack. Each finger is made independently spring-loaded, and pin springs are located above said axis.

EFFECT: higher product stacks grip and hold reliability.

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Description

Field of technology to which the invention relates

The invention relates to the field of gripping devices, in particular, devices for gripping stacks.

State of the art

A device and method for capturing, molding and laying thin glass panels is known (RU2715162C1, publ. 2020.02.25). The known solution relates to a device and method for gripping, forming and laying thin glass panels. The device includes a frame with a top and a bottom that is designed to face a glass panel less than 1 mm thick and that is provided with a plurality of gripping pins that are arranged substantially parallel to each other and the end facing the glass panel is provided with a suction cup, the gripping pins being independently movable from each other along the direction of their extension in order to adapt the location of the suction cups to the intended shape of the glass panel. The device allows you not only to grab, carry and lay thin glass panels, but also to mold them, which expands its functionality.

However, this solution, although it contains spring-loaded independent fingers, cannot be effectively used for gripping stacks of products.

An industrial robot clamp is known (CN216577961U, publ. 2022-05-24). The known solution discloses an industrial robot gripper including a bottom plate and a movable plate, the bottom plate including: a clamping device including a drive unit, a pressure plate, a pressure air cushion and a shock-absorbing assembly. The angle of the clamping plate can be adjusted by adjusting the adjusting component so that it can adapt to the object being clamped. The clamping device is suitable for gripping objects of various shapes, such as blocks, round pipes and the like. The range of application is expanded due to the clamping air cushion and shock-absorbing unit. Damage to the object is eliminated and the reliability of gripping an object of complex shape is improved.

However, this solution cannot be effectively used for gripping stacks of products, since it is adapted for gripping a single object.

The robot hand is known (JP2008100323A, 2008-05-01). A known solution is a two-fingered robotic arm having a mechanism that prevents the object being grasped from falling, even if the command value to the actuator for driving the fingers becomes zero. The technical implementation of the robot's fingers is as follows: each finger contains three phalanges connected to each other by a leaf spring. The fingers are covered with non-slip elastic material on the side in contact with the object being grasped. The object to be grasped is grasped by the linear movement of the first phalanx due to the rotation of the rotary shaft 9 of the actuator 10. When the first phalanx comes into contact with the object to be grasped, the first leaf spring and the second leaf spring are deformed, causing the second phalanx to come into contact with the object to be grasped. The proposed robot's hand can reliably grasp an object of complex shape due to the tension of leaf springs.

This solution uses leaf springs, which have a relatively small operating range, and is also adapted to gripping a single object rather than stacks.

Disclosure of the Invention

In one aspect of the invention, a stack gripping device is disclosed, comprising:

- power drive;

- capture block;

characterized by the fact that

the power drive is configured to control the gripping unit so as to clamp the stack,

- the gripping unit contains two gripping elements containing a plurality of fingers,

the fingers are parallel plates designed to rotate on a single axis on the gripping element,

each finger is spring-loaded.

In additional aspects, it is disclosed that the side of each finger in contact with the stack is coated with an anti-slip coating; the springs of the outer fingers can be made more rigid; finger springs are located above the rotation axis; fingers have a U-shaped profile; fingers have an inclination to the vertical from 2 to 10 degrees.

The main problem solved by the claimed invention is the creation of a stack gripping device that reliably holds stacks of products of differing lengths.

The essence of the invention lies in the fact that the gripping unit contains a plurality of fingers installed with the ability to rotate independently relative to each other on a common axis so that the fingers independently grip objects, in particular, stacked products. In this case, the fingers are spring-loaded so that it is possible to clamp the products.

The technical result achieved by the solution is to increase the reliability of gripping and holding a stack of products.

Brief description of drawings

Fig.1. shows part of the gripper block with multiple spring-loaded fingers.

Carrying out the invention

Part of the capture block is shown in Fig. 1, in which:

101 – frame;

102 – fingers;

103 – springs;

104 – rotation axis.

All elements of the claimed device are connected to each other structurally and functionally through assembly operations. The device is manufactured at the manufacturer's factory. Figure 1 shows only part of the gripping block, the other part is made symmetrically. The gripping unit contains at least a frame 101, fingers 102 mounted on it, and power drive elements are also installed on it. The gripping unit is connected to the remaining parts of the claimed device, which provides at least the possibility of moving the gripping unit relative to the stack being grabbed.

The frame 101 contains an elongated horizontal frame, at both ends of which fingers 102 are installed for gripping products. The frame 101 can have different designs, adapted for the capture and movement of certain products. The part of the frame 101 on which the pins 102 (frame) are mounted must be of such length and width as to be able to cover the stack of products, that is, it must be longer and wider than the stack.

In this description, a stack means at least one row of homogeneous products, for example, pipes, rolls, timber. In practice, these products have slightly different lengths, which does not allow them to be grasped with one flat grip. Since such a grip will only clamp the longest product.

To solve this problem, it has been proposed to create a gripper with multiple fingers, each of which can adapt to the length of the product it grips. Thus, at least one finger grips one product of a row, adjacent fingers grip adjacent products.

A stack may contain two or more rows of products, which can also be captured by the claimed solution. In the space between the fingers of two hands (for simplicity, the set of fingers on one side is called a hand here) you can place a stack approximately the length of the fingers. Since there may be longer items in the upper rows that will prevent the lower rows from being captured, the claimed solution provides additional options to overcome these problems.

The proposed frame 101 contains a horizontal frame with a movable part on which fingers 102 are fixed. The movable part is configured to move along the frame to increase and decrease the space between the fingers 102. Before grasping products using a power drive (not shown in Fig. 1), the space between the fingers 102 is increased and decreased. the distance between the fingers is 102, and to grip products this distance is reduced.

The power drive may be a servo drive, a stepper motor, a hydraulic power drive, etc. The moving part can move along the frame on guides of any type, which is not the essence of the claimed solution.

The fingers 102 are elongated plates with stiffening ribs along both long edges of the plate, that is, they have a U-shaped profile, preferably the height of the ribs decreases towards the ends of the fingers. Stiffening ribs are needed to ensure sufficient compression force and reliable grip of products. Preferably, the axis 104 on which the fingers rotate is located at the top of the fingers, which allows for secure gripping of a stack of products of varying lengths. That is, all other things being equal, the closer the rotation axis 104 is to the upper edge of the fingers, the greater the difference in the lengths of the gripped products is allowed.

Mounted at the top of the pins (above the pivot axis 104) are springs 103, with each pin 102 having its own independent spring 103. These springs 103 allow each pin 102 to independently clamp items in a stack. It is preferable to locate the springs 103 at the very top of the pins 102 so that they work in compression, since the tensile work causes the springs 103 to become detached from the pins 102 or the frame 101, which can cause failure of the corresponding pins.

The parameters of the fingers 102 are selected based on the parameters of the gripped products. The greater the weight of the products, the greater the load the fingers 102 must cope with, that is, the appropriate material must be selected, sufficient thickness must be determined, restrictions must be placed on the length of the fingers 102, etc. The greater the difference in the lengths of the products to be grasped, the greater the length of the fingers 102 must be. Without creative effort, one skilled in the art will be able to select the material, length, thickness of the fingers 102, etc., to ensure reliable operation of the inventive device.

The number of fingers 102 is selected based on the length of the product to be grasped, its shape, and the requirements for gripping force. The more fingers 102 are used, the better the adaptation to the shape of the individual product in the stack. It is preferable to have at least three fingers per product to ensure a secure grip by adapting to possible unevenness in the end of the product being grasped.

The shape and parameters of the fingers 102 can vary depending on the parameters of the object being grasped: the fingers 102 can be of uniform width, tapering, widening, can be curved or straight, can contain spikes, grooves, projections perpendicular to the fingers, etc.

The frame 101 includes a part that is fixed to the floor and a part to which the fingers are attached. The features of the 101 framework are not disclosed in detail here, since this is not relevant to the essence of the solution. The frame 101 may include means for moving the captured stack, but this is also not the essence of the claimed solution.

The frame 101 contains a power drive that spreads the fingers of the gripping unit before the actual gripping and brings the fingers together during the gripping process. The gripping unit contains a plurality of fingers with elements for fastening the fingers to the frame. When the fingers move together (closer to each other), some of them come into contact with the products in the stack earlier, some later. Thanks to the springs 103, after the first fingers have already clamped the products, the other fingers still continue to close until they grasp the products that are located between them.

There are limitations to the ability to grip products that differ greatly in length, however, in practice, products in one stack differ in length by no more than 5%; the claimed design of the gripping device can compensate for such a difference due to the correct choice of the lengths of the fingers 102.

Description of the device operation

The device for grabbing stacks is controlled manually by the operator or operates in an automated or automatic mode based on signals from a control unit that analyzes data from sensors.

When a stack of products is placed in a given location, the gripper moves the frame 101 to an area above the stack, spreading the fingers 102 to a distance greater than the maximum length of the products in the stack. Then the frame 101 is lowered to the level necessary to grip the stack with fingers 102, the fingers 102 are brought together until all covered products are captured and the stack is raised.

The moment when the stack is picked up can be monitored visually by the operator or by a computer vision system. In another embodiment, a system of strain gauges on each finger may be used. As soon as the pressure at each load cell exceeds a threshold value, the gripping stops and the lifting of the stack begins.

In another embodiment, the maximum value on any of the load cells is monitored; as soon as the maximum threshold is exceeded on any of the load cells, the capture stops. A combination of the proposed options or a combination of the proposed and other options known from the prior art for monitoring the moment of completion of the capture can be used.

The movement of the captured stack is carried out within the working area of the device for capturing stacks. It can load stacks onto a conveyor, into a container, etc.

Embodiment 1

In one embodiment, the side of each finger 102 that contacts the stack is coated with an anti-slip coating, such as silicone, rubber, ribbed or studded material.

In some embodiments, the fingers 102 contain rubber pneumatic cushions, which allow the fingers 102 to better adapt to the shape of the product being covered and provide uniform compression of the products.

Option 2

In one embodiment, the outer finger springs are made more rigid. This allows you to more reliably grab the outermost products in the stack, which increases the reliability of gripping and moving the stack, since the outermost elements bear an increased load, and the likelihood that they will fall out during movement is higher.

Option 3

In one embodiment, the fingers are inclined from 2 to 10 degrees from the vertical, that is, the lower ends of the fingers 102 of the two hands are closer to each other compared to the upper ends. This allows you to more reliably grab the products, since with the same gripping force it is easier to slip out of vertical fingers than from inclined ones, and this design also better grips a stack in which the products of the top row are longer than the products of the bottom row.

At the same time, at angles greater than 10 degrees, the likelihood increases that one of the ends of the captured product will move upward, because of this the second end will slip out of the grip and the entire product will fall out.

The embodiments are not limited to the embodiments described herein, but other embodiments without departing from the spirit and scope of the present invention will become apparent to one skilled in the art based on the information set forth in the specification and knowledge of the prior art.

Elements referred to in the singular do not exclude the plurality of elements unless specifically stated otherwise.

The functional connection of elements should be understood as a connection that ensures the correct interaction of these elements with each other and the implementation of one or another functionality of the elements. Particular examples of functional communication may be communication with the ability to exchange information, communication with the ability to transmit electric current, communication with the ability to transmit mechanical motion, communication with the ability to transmit light, sound, electromagnetic or mechanical vibrations, etc. The specific type of functional connection is determined by the nature of the interaction of the mentioned elements, and, unless otherwise indicated, is provided by widely known means, using principles widely known in the art.

The methods disclosed herein contain one or more steps or actions to achieve the described method. The steps and/or actions of the method can replace each other without going beyond the scope of the claims. In other words, unless a specific order of steps or acts is specified, the order and/or use of specific steps and/or acts may be varied without departing from the scope of the claims.

While exemplary embodiments have been described in detail and shown in the accompanying drawings, it is to be understood that such embodiments are illustrative only and are not intended to limit the broader invention, and that the invention is not intended to be limited to the specific arrangements and structures shown and described. since various other modifications may be apparent to those skilled in the art.

The features mentioned in the various dependent claims, as well as the implementations disclosed in various parts of the description, can be combined to achieve beneficial effects, even if the possibility of such combination is not explicitly disclosed.

Claims (13)

1. A device for grabbing stacks, containing: - power drive; - capture block; characterized by the fact that the power drive is configured to control the gripping unit so as to clamp the stack, the gripping unit contains two gripping elements containing a plurality of fingers, the fingers are parallel plates designed to rotate on an axis on the gripping element when gripping a stack, each finger is independently spring-loaded, and the finger springs are located above said axis. 2. The device according to claim 1, in which the side of each finger in contact with the stack is covered with an anti-slip coating. 3. The device according to claim 1, in which the springs of the outer fingers are made more rigid. 4. The device according to claim 1, in which the fingers have a U-shaped profile. 5. The device according to claim 1, in which the fingers are inclined to the vertical from 2 to 10 degrees. 6. The device according to claim 1, in which the number of fingers is set so that each product in the stack is grasped by at least three fingers.