JPH0112635B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of accurately positioning the reference part of a workpiece gripped by a hand, thereby ensuring reliable transfer of the workpiece to and from a counterpart machine, and at the same time, when transferring the workpiece, the grip center of the counterpart machine and the center of the workpiece can be accurately positioned. To provide a handling device that can smoothly transfer a workpiece without causing any inconvenience such as dropping the workpiece even if there is some deviation between the two.

A handling device that has a hand that grips a workpiece by bringing a pair of opposing gripping members close to each other and releasing the workpiece by moving them apart, transfers the workpiece to a machine such as a lathe, and also receives the workpiece from the machine. It has been widely used as an automated device for

An important point in this type of handling device is that it is possible to accurately position the workpiece so that when it is gripped by the hand, the reference part of the workpiece is always at a fixed position when viewed from the reference point, for example, the center point of the base of the hand, and that it can be repeatedly It must be highly accurate, and must be such that the workpiece does not move or fall off in the gripping member during the process of loosening the gripping force on the side currently gripping and then gripping the receiving side. Two points in particular are worth mentioning.

However, in most conventional handling devices, a pair of gripping members are moved toward and away from each other in a centripetal synchronized state, and although in principle the center of gripping the workpiece is always at a constant position when viewed from a reference point,
It is natural for an actuator for moving a gripping member, such as a hydraulic cylinder, to grip a workpiece at an intermediate position before the piston reaches the end position. Unless they match, it is not possible to maintain the gripping center in a fixed position, and therefore, in order to improve positioning accuracy, the hand must have a precise structure, resulting in an unavoidable problem of increased costs.

Furthermore, with such a structure, if an external force greater than or equal to the gripping force of the gripping member is applied to the workpiece in the opposite direction to the gripping force (this occurs when the gripping center of the hand and the gripping center of the other machine do not match). ), the force that tries to spread one gripping member will naturally act on the other gripping member that moves synchronously in the expanding direction, causing the workpiece to drift between the gripping members and cause axial deviation. This is undesirable because it can lead to accidents in which the workpiece becomes detached from the hand and the gripping part of the other machine and falls off, making it impossible to accurately transfer the workpiece to and from the other machine. .

The present invention has been made in view of the fact that the conventional handling devices have various problems. In the hydraulically driven handling device, the reciprocating actuators 5, 6 have hands 1 connected to the reciprocating actuators 5, 6, respectively, so as to be able to move forward and backward toward and away from each other on one axis X.
are pistons 20, 21 movable on one axis X
and a cylinder 2 enclosing the pistons 20 and 21.
2 and 23, and rods 24 and 25 respectively disposed on the end face on the moving direction side of the first piston 20 and the end face on the opposite moving direction side of the second piston 21 during the gripping operation. The double-acting cylinders 5, 6 are formed of rod double-acting cylinders 5, 6.
via the rods 24, 25, the gripping members 3, 4
while connecting the first piston 20 to the second piston 21 so that the area of action for the hydraulic pressure on the head side of the first piston 20 is
The acting area on the rod side of the first piston 20 is formed to be larger than the acting area on the rod side, and the acting area on the rod side of the first piston 20 is formed to be smaller than the acting area on the head side of the second piston 21, Hydraulic circuit 2 shared by both double-acting cylinders 5 and 6
, by operating the switching valve 7 on the grip side, the first piston 20
Hydraulic pressure is simultaneously applied to the head side of the double-acting cylinder 5 having the second piston 21, and to the rod side of the double-acting cylinder 6 having the second piston 21. It is characterized by being formed into a meter-out circuit whose speed is controlled by a flow rate control valve 8.

In the present invention configured as described above, when the switching valve 7 is operated to switch to the gripping side, the hydraulic pressure applied to both the double-acting cylinders 5 and 6 gradually increases to reach the pressure that operates the double-acting cylinder 5 with the smaller load. Then, as the first piston 20 moves, the pressure becomes constant,
When the piston 20 reaches the end of the cylinder 22 and finishes moving, the oil pressure starts to rise again, and when it reaches the pressure that activates the double-acting cylinder 6, which has a large load, the second piston 21 starts moving, and the pressure remains constant. and moves until the gripping operation is completed.

When the gripping operation is completed, the gripping operation continues with a constant pressure.

In this way, the gripping position is always held constant.

On the other hand, even if an external force acts on the workpiece being gripped, and this force exceeds the piston pressing force of the double-acting cylinder 5, causing the gripping member 3 to move backward in the opposite direction to the gripping direction, the double-acting cylinder 6 Since hydraulic pressure is applied to advance the gripping member 4 in the gripping direction, the gripping member 4 moves along with the workpiece while remaining in contact with the workpiece.
The grip on the workpiece continues without being released.

Therefore, the workpiece will not fall off during delivery.

Embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

In FIG. 1, 1 is a hand, 2 is a hydraulic circuit, and the hand 1 has a pair of gripping members 3 and 4 provided oppositely connected to reciprocating actuators 5 and 6, respectively. The gripping members 3 and 4 are movable toward and away from each other at the top.

The gripping members 3 and 4 are clamped in contact with the circumferential surface of the cylindrical workpiece W, thereby gripping the workpiece W.
Each of the gripping members 3 and 4 is fixed to each rod end of the reciprocating actuator 5 and 6.

Thus, the reciprocating actuators 5, 6 include pistons 20, 21 that are movable on one axis X, and cylinders 22, 23 that enclose the pistons 20, 21.
and rods 24, 2 disposed on the end face of the first piston 20 in the moving direction and the end face of the second piston 21 in the opposite moving direction during the gripping operation.
a pair of single-rod double-acting cylinders 5,
6, the double-acting cylinders 5, 6 are connected to the gripping members 3, 4 via rods 24, 25, respectively, while the area of action for the hydraulic pressure on the head side of the first piston 20 is connected to the second piston 20. The working area on the rod side of the first piston 20 is formed to be larger than the working area on the rod side of the piston 21, and the working area on the rod side of the first piston 20 is formed to be smaller than the working area on the head side of the second piston 21. , the illustrated example uses double-acting cylinders of the same shape and capacity.

Next, regarding the hydraulic circuit 2, the double acting cylinder 5,
Both cylinders 5 and 6 are operated simultaneously.
A switching valve 7 for switching the flow of pressure oil, which is a circuit shared by the
Flow control valves such as variable throttle valves 8 and 9, check valve 1
0 and 11 as controllers.

The solenoid valve 7 is a two-position type that operates the hand 1 toward the release side by energizing the solenoid S _A , and conversely operates the hand 1 toward the gripping side by energizing the solenoid S _B. is equipped with check valves 10 and 11 in parallel, and the variable throttle valve 8 has a function of controlling the moving speed of the rod by adjusting the amount of pressure oil in the reservoir line during grip side operation by energizing the solenoid S _B. Therefore, hydraulic circuit 2
is formed into a meter-out circuit.

Note that the present invention requires that the speed be controlled by a flow rate control valve commonly provided on the outlet sides of both double-acting cylinders 5 and 6 when the cylinder is operated to the gripping side. The meter-out circuit is necessary for the grip-side operation, and is not necessarily required for the release-side operation.

Next, the operation of the handling device with the above configuration will be explained. Solenoid S _B is energized, hydraulic circuit 2 is set on the gripping side, and speed control is performed using a meter-out circuit with variable throttle valve 8 on the reservoir line side. When this is done, the piston of the double-acting cylinder 5 first moves to the right, causing the gripping member 3 to move rightward in FIG. When the piston moves to the left and both gripping members 3 and 4 grip the workpiece W under a predetermined pressure, the piston stops moving.

Thus, in the process of operation of both double-acting cylinders 5 and 6, it is natural that the double-acting cylinder 5 operates first, rather than simultaneously, for the following reasons.

That is, the outlet side pressures of the double-acting cylinders 5 and 6 are kept at the same pressure by the variable throttle valve 8, and the piston area facing the outlet side of both cylinders 5 and 6 is larger for the double-acting cylinder 6. It is larger than the double acting cylinder 5.

Therefore, when comparing the reaction forces when moving the pistons of double-acting cylinders 5 and 6, the double-acting cylinder 6
indicates a larger value.

On the other hand, double-acting cylinder 5 has a larger piston area facing the inlet side of double-acting cylinders 5 and 6, and the same amount of oil pressure is applied to it, so double-acting cylinder 5 has a larger force pushing the piston. Needless to say, it is.

From the relationship between these acting forces and reaction forces, it is easily understood that the double acting cylinder 5 operates first, and then the double acting cylinder 6 operates.

When the workpiece W is gripped by both gripping members 3 and 4, pressure is applied to the piston of the double-acting cylinder 5 on the head side, and pressure is applied to the piston of the double-acting cylinder 6 on the rod side. The acting force of the double-acting cylinder 5 is large corresponding to the cross-sectional area of Accurate positioning is necessarily guaranteed, and positional errors due to repeated operations do not occur at all.

In addition, if you want to set the position of the central axis from the base of the handling device to remain unchanged even if the cross-sectional diameter of the cylindrical workpiece W changes, set the radius based on the maximum diameter of the workpiece W. A spacer 12 (see FIG. 3) having a thickness corresponding to the difference may be attached to the gripping member 3.

With the workpiece W being gripped by the hand 1 in this way, a leftward force F as shown in FIG. Even if the force is stronger and the gripping member 3 moves backward, the double-acting cylinder 6 applies pressure to the rod side of the piston, so the gripping member 4 moves to the left along the workpiece W.

Therefore, the gripping by the gripping members 3 and 4 is not released, and when the workpiece W is transferred to and from the gripping portion of a mating machine such as a lathe, the gripping center line L ₁ of the gripping portion and the hand 1 In many cases, a deviation as shown in FIG. 2 occurs between the gripping center line L ₂ of the workpiece W and the gripping center line L 2 of the workpiece W, as shown in FIG. 3,
It is possible to stably transfer the workpiece W without causing it to fall off from the workpiece 4.

However, if a force in the opposite direction to the leftward force F is applied, there is a risk that the grip will be released, so it is preferable to take this into consideration at the time of device design to prevent such force from being applied.

Next, FIG. 3 shows the specific structure of the hand 1 according to the device of the present invention, in which single-rod type double-acting cylinders 5 and 6 are arranged in parallel on the hand base 13, and the tip of each rod is are connected to base materials 14 and 15 to which gripping members 3 and 4 are respectively fixed.

Note that 16 in FIG. 3 is a guide member that is integrally fixed to the hand base 13, and guide rods 17 and 18 protruding from each base material 14 and 15 can be slid into through holes provided at corresponding locations. This is to hold the gripping members 3 and 4 so that they can move correctly along one axis X without being biased.

Reference numeral 12 denotes a positioning spacer, which has a thickness that corresponds to the change in the radius of the workpiece W, and is interposed between the base material 14 and the gripping member 3, so that the center of the gripped workpiece can be As mentioned above, the purpose is to maintain the position at a relatively constant position.

The illustrated hand 1 has a helical thread groove cut in the tip of the guide rod 17 on the opposite side to the base material 14, and a nut is screwed into this portion to adjust its in/out dimension so that it comes into contact with the guide member 16. By appropriately determining the position, this nut can be replaced by the spacer 12.

Since the present invention has the configuration and operation as described above, when it is operated in the direction of gripping a workpiece, pressure is applied to the head side of the first piston 20, which has a larger area of action. The double-acting cylinder 5 first operates to move the gripping member 3 to a certain position corresponding to the cylinder end, and then the double-acting cylinder 6 operates to move the gripping member 4 to the position where it contacts the workpiece. As a result, the gripped workpiece is positioned at a location corresponding to the end of the double-acting cylinder 5, and accurate positioning is achieved.

This allows accurate alignment during transfer between the handling device and a machine tool such as a lathe to which the work is transferred.

Furthermore, as is clear from the explanation based on FIG. , 4 continue to grip the work while accompanying the movement of the work, this eliminates the inconvenience of the work falling off from the hand 1 during handover, and also prevents damage to each part of the hand 1, the work, and the machine tool. It has excellent effects such as not giving any mechanical shock.

[Brief explanation of drawings]

FIG. 1 is a schematic structural diagram of an example of the device of the present invention, FIG. 2 is an explanatory diagram of the operation, and FIG. 3 is a cross-sectional structural diagram of a hand according to an example of the device of the present invention. DESCRIPTION OF SYMBOLS 1... Hand, 2... Hydraulic circuit, 3, 4... Gripping member, 5, 6... Single rod type double acting cylinder, 7
...Switching valve, 8...Flow control valve, 20...First piston, 21...Second piston, 22...Cylinder, 23...Cylinder, 24...Rod, 2
5... Rod, X... One axis.

Claims (1)

[Claims] 1 A pair of gripping members 3 and 4 provided facing each other are connected to reciprocating actuators 5 and 6, respectively, and a single axis
Hand 1 that can move forward and backward toward and away from each other at the top
In a hydraulically driven handling device having
The reciprocating actuators 5 and 6 include pistons 20 and 21 that are movable on one axis X, and the piston 2
cylinders 22 and 23 enclosing the pistons 0 and 21, and rods 24 respectively disposed on the end face on the moving direction side of the first piston 20 and on the end face on the opposite moving direction side of the second piston 21 during the gripping operation. , 25, and the double acting cylinders 5, 6 are connected to the rods 24, 2.
5 to the gripping members 3 and 4, respectively, and the first piston 20 on the head side has a working area for hydraulic pressure larger than the working area on the rod side of the second piston 21. In addition, the working area on the rod side of the first piston 20 is formed to be smaller than the working area on the head side of the second piston 21, and the hydraulic circuit is common to both the double-acting cylinders 5 and 6. 2, when the switching valve 7 is operated on the grip side, hydraulic pressure is simultaneously applied to the head side of the double-acting cylinder 5 having the first piston 20 and to the rod side of the double-acting cylinder 6 having the second piston 21, and A handling device characterized in that it is formed in a meter-out circuit whose speed is controlled by a flow rate control valve 8 provided in common on the outlet sides of both double-acting cylinders 5 and 6.