DD219720A1 - WORKPIECE GRIPS FOR HANDHELD HOLDERS - Google Patents

Abstract

The invention is applicable to hydraulically operated jaws with rectilinear gripper jaws for industrial robots and handling devices. The aim of the invention is to provide a workpiece gripper, which is equipped with optimal safety technology, it has low mass and is inexpensive to produce. It is an object of the invention to bring about by reducing the components required for function and safety as well as optimal arrangement of a compression spring with a flat characteristic a reduction in mass, cost and the required sealing points, while improving the safety function. According to the invention this is achieved in that the piston arranged for the closing operation is combined with the spring-loaded pressure piston of the security element to form a component. This piston combination is advantageously designed as a stepped piston with a Kolbenflaechenverhaeltnis A: a 1.2 ... 2. At the end of the closing process of the workpiece gripper increasing oil pressure leads to an axial displacement of the piston combination, wherein the compression spring of the security element is stretched. If the oil pressure in the supply line to the gripper drops as a result of pipe rupture, the force stored by the pressure spring produces a relatively high oil pressure by displacement of the piston combination, since the stepped piston acts as a pressure converter.

Description

Workpiece gripper for handling devices Field of application of the invention

The invention is applicable to workpiece grippers of industrial robots, especially in jaw grippers with rectilinearly moving gripper jaws.

Characteristic of the known technical solutions -

There are hydraulically driven workpiece gripper for handling devices are known which are equipped with rectilinearly movable gripper jaws, which serve as a drive of the gripper jaws in the housing of the gripper mounted plunger (DD-WP 0154 432). To ensure the tensioned state of the gripper, even in case of power failure, e.g. By burst pipe, special security elements are provided. This can be z. B. be a spring disc brake (DD-WP 0154 433), which mechanically holds the gripper jaws on intermediate links such as pinion and racks.

Also known is a special circuit arrangement for the hydraulic actuation of jaws (DD-WP 158 718), in which a pilot-operated check valve is provided, which prevents a flow back of the pressure oil after completion of the clamping operation. Although the arrangements described block the clamping state of the gripper jaws that has just been assumed, they have the disadvantage that the tension force is no longer present when the system changes its position as a result of external forces or losses due to leakage.

There are therefore also known variants of workpiece grippers, bsi where the clamping force is maintained in the event of an accident by a hydraulic pressure accumulator (TGL 39 506). The preferably equipped with disc springs and single piston safety element is arranged separately and communicates with the actuating piston for the clamping movement of the workpiece gripper only in line connection. The steep characteristic of the disc springs is unfavorable for the holding function of the gripper in case of power failure. The disadvantage is further characterized in that the relatively large;

Sicherheitsseiemente must be located directly on the workpiece gripper, which leads to an increase in the moving mass of the same i and thus to a reduction in the workpiece material to be handled.

Other known designs of workpiece grippers are not optimally designed due to the lack of security elements directly on the gripper (DD-WP 0152 087).

Object of the invention

The invention aims to provide a hydraulically actuated workpiece gripper, which is equipped with optimum safety technology, it has low mass and konstengünstig is produced. , '

Explanation of the essence of the invention

To eliminate the shortcoming of the known technical solutions, the invention has the object, by reducing the components required for the function and safety and optimal arrangement of a compression spring with a flat characteristic reduction in mass, the cost * and the number of required sealing points to bring about while improving the safety function. <

According to the invention this is achieved in that the piston provided for the closing operation is combined with the spring-loaded pressure piston of the pressure accumulator to form a component. This piston combination is advantageously designed as a stepped piston with a piston area ratio A: a = 1.2 ... 2. At the end of the closing process of the gripper leads the rising

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Oil pressure to an axial displacement of the piston combination upwards, wherein the compression spring is tensioned. If the oil pressure in the supply line to the gripper decreases ^ then stored in the compression spring force by displacement of the piston combination down an oil pressure. Viewed without efficiency, the magnitude of the oil pressure corresponds to the spring force divided by the difference between the large piston area A and the small piston area a of the piston combination. By favorable choice of Kdlbenflächenverhältnis A / a in the range 1.2 ... 2, a high oil pressure can be maintained with a spring with a relatively small force, since the stepped piston acts as a pressure booster. This makes it possible to form the compression spring with a large ratio of outside diameter to wire diameter, which desirably leads to a small force change in the range of Nutzstoffbeitshubes. In addition, a compression spring of large diameter, but short length to accommodate cheap in the gripper.

embodiment

The invention will be explained below with reference to the drawing of an embodiment. The workpiece gripper consists of a housing 1, with which the jaw 2 is firmly connected. The counter-jaw 3 is linearly displaceable on guide column 4. For opening the gripper piston 5, for closing piston 6 is arranged. Both pistons are designed as one-sided plunger and provided with seals 24,25. Through the central bores 7.8 of the piston 5.6, the pressure oil can flow into the cylinder chambers 19,20. Ally with the housing is the security element 9, which consists of a combination of unblockable check valve 10 and a pressure accumulator '. This pressure accumulator is formed by a pressure piston 11, which is sealed in the housing 1 with seal 26 and loaded by compression spring 14. According to the invention, the piston 6 is joined together with the pressure piston 11 to the piston combination 6/11. A collar 12 in the recess 13 limits the axial stroke of the piston combination 6/11. Between compression spring 14 and piston combination ^+! on 6/11 the spring plate 18 is arranged oscillating.

The operation of the workpiece gripper is the following: So that the workpiece gripper closes, 21 pressure oil must be supplied to the pressure port. This flows via blocking element 16 in the pressure chamber 15, further through transverse bore 17 and central bore 8 in the cylinder chamber 20 and pushes the counter-jaw 3 down. At the same time the existing oil in the cylinder chamber via central bore 7, line 22 and pressure port 23 is discharged. .. |

When jaw 2 and jaw 3 have engaged the workpiece, the oil pressure increases. As a result, the piston combination 6/11 is displaced upwards as far as the collar 12 and the recess 13 allow; the compression spring 14 is tensioned. If, in the event of a malfunction in the hydraulic system, the oil pressure in the pressure port 21 drops, blocking element 16 prevents the oil in the pressure chamber 15 from flowing to the pressure port 21. The tensioned compression spring 14 presses on the piston combination 6/11 and generates an oil pressure, which is dependent on the spring force of the compression spring 14 and the area difference (A-a). Thus, a sufficient clamping force of the workpiece gripper is maintained even in case of failure of the hydraulic system, which changes only slightly in the range of the intended stroke range of the piston combination 6/11 by the flat characteristic of the compression spring 14 used.

If the workpiece gripper open, so must be supplied to the pressure port 23 pressure oil. Djes flows via pipe 22 to the cylinder chamber 19. At the same time, the blocking element 16 is opened via piston 27, so that the oil can flow out of the cylinder chamber 20. ''''': · .-: · - · ^: ·.

Claims (4)

Invention claims: ' 1.5. the piston combination (6/11) is designed as a stepped piston, wherein the larger piston with the piston surface A inherhalb * the counterjaw (3) and the smaller piston with the piston surface a in the security element (9) dense, but displaceable is arranged. , , ' 1.4. the piston rod side end of the Kolbenkombinatipn (6/11), and the compression spring (14) are in a pressure chamber (15) which on the one hand by the locking element (16) of the pilot-operated Rückschlagveritiles (10) is completed, on the other hand by transverse bores (17) and central bore (8) of the piston combination (6/11) is in line communication with cylinder space (20), 1.3. in the axial direction behind the Kolbenkombinatidn (6/11) a compression spring (14) is arranged, 1.2. the piston combination (6/11) has a collar (12) which is located in the recess (13) of the housing (1), which is designed so that a limited axial movement of the piston combination (6/11) is possible, 1.1. the piston (6) provided for the clamping operation of the workpiece gripper and the pressure piston (11) are combined to form a piston combination (6/11), 1. workpiece gripper for handling devices, consisting essentially of - a housing,. ". '. - A tightly connected to the housing jaw - A counter-jaw, which is linearly displaceable on a guide - Two mounted in the housing, acting on the counter-jaw piston with a central bore for the pressure oil supply - A security element to ensure the tensioned state of the workpiece gripper in case of power failure, consisting of a combination of unblockable check valve and spring-loaded pressure piston, characterized in that; : 2. workpiece gripper according to item 1, characterized in that the designed as a stepped piston piston combination (6/11) is designed / that on counter-jaw (3) acting piston surface A 1.2 ... 2 times the size of the pressure chamber (15) acting Kolbehfläche has a. '·' Γ 3.2. the compression spring (14) has a large ratio of outer diameter / wire diameter, whereby a low spring stiffness is conditional. 3.1. the compression spring (14) is designed as a helical spring, 3. workpiece gripper according to item 1 and 2, characterized in that 4. workpiece gripper according to item 1 to 3, characterized in that the frictional connection between the compression spring (14) and the Kolbenkombihation (6/11 (, by a spring plate (18) is formed on the piston rod side end of the piston combination (6 / 11) pendulum supports. 1 page drawings, ·