JPH0366998B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a hydraulically operated pressing device.

B. Purpose of the Invention Prior Art A stroke performed by a hydraulically operated pressing device such as a hydraulic press, a hydraulic shearing device, a hydraulic oil pump, etc. is a stroke _L1 until the presser hits the object to be pressed, and an action stroke that occurs subsequent to the stroke _L1 . L ₂ and stroke _{L 1 do} not need to occur at the same speed, and the feed speed can be increased for strokes in no-load conditions and strokes in near-no-load conditions. desirable. In order to operate the device under these conditions, 1. Install one hydraulic pump with a large capacity and control its discharge volume. 2. Install a low-pressure pump with a large capacity and a high-pressure pump with a small capacity. Possible methods include controlling and using them with an appropriate control system, 3. Attaching an appropriate boosting mechanism to the hydraulic cylinder device, and operating the boosting mechanism as necessary. Adoption of means tends to increase the external dimensions of the device system and complicate the control system, and the cost required for installing the means tends to increase.

Problems to be Solved by the Invention The problem to be solved by the present invention is to develop a hydraulically operated pressing device that avoids the drawbacks listed in 1, 2, and 3 above.

B. Means for Solving the Constituent Problems of the Invention The hydraulically operated pressing device according to the invention includes a piston-cylinder device in which a piston is a presser containing oil, and a plunger that is moved in the axial direction by screw feeding. It is slidably fitted into the cylinder head and the top of the piston of the piston/cylinder device, and the diameter of the oil holding space of the pusher is made larger than the diameter of the plunger, so that the plunger slides against the top of the piston/cylinder device. During the transition period until the movable fitting is released and the oil holding space of the presser communicates with the space between the cylinder head and the top surface of the piston of the piston-cylinder device, A relief valve is provided that opens when the oil exceeds a specified value to provide the communication, and also supplies oil between the cylinder head of the piston-cylinder device and the top surface of the piston, and discharges oil from the space. An oil tank is provided to receive oil, and when the plunger of the piston-cylinder device enters the oil holding space of the pusher, it is in a closed state, and when the plunger is integrated with the piston, it is in the open state during fast forwarding and fast returning. A suction/return device that takes a state is interposed on the flow path between the tank and the piston/cylinder device, and the speed change range includes a point where the rotational speed of the output shaft is 0, and the rotation of the output shaft as the load torque increases. The present invention is characterized in that a continuously variable friction transmission whose speed decreases toward zero is provided on the screw feed drive system.

Effect The device according to the present invention described above is a “friction continuously variable transmission in which the speed change range includes a point where the rotational speed of the output shaft is 0, and the rotational speed of the output shaft is decreased toward 0 as the load torque increases.” The characteristics of are used to drive the presser, and the distance the presser travels until it hits the object to be pressed.
Since the load torque is small, L ₁ is performed at high speed by increasing the rotational speed of the output shaft of the friction continuously variable transmission, while the pusher performs work while exerting force on the pressed object. _L2 is performed by lowering the rotational speed of the output shaft of the friction continuously variable transmission so as to increase the pressing force exerted by the presser on the object to be pressed. The rotational speed of the output shaft of the friction continuously variable transmission is a function of the magnitude of the reaction force exerted on the presser by the object to be pressed, and changes automatically according to the nature and state of the object to be pressed. That is,
Comparing when the deformation resistance of the pressed object is small and when the deformation resistance of the pressed object is large, the rotational speed of the output shaft of the friction continuously variable transmission is higher in the former state than in the latter state. big. The device according to the present invention includes a friction continuously variable transmission in which the speed change range includes a point where the rotational speed of the output shaft is 0, and the rotational speed of the output shaft decreases toward 0 as the load torque increases, as shown in FIG. Since it has a "torque-rotation speed characteristic," this characteristic is utilized to downsize the device.

Embodiment In FIG. 1, the reference numeral 1 designates a piston-cylinder device in which a piston is a pusher 2 containing oil therein, and the reference numeral 3 designates a cylinder head of the piston-cylinder device 1. Reference numeral 5 denotes a plunger that is moved in the axial direction by a screw feed to apply a pressing thrust to the pusher 2, and this plunger 5 is drivingly connected to an output shaft 9 of a friction continuously variable transmission 8 whose driving source is an electric motor 4. . Reference numeral 6 denotes a rod for preventing rotation of the feed nut 7 which is threadedly fitted into the plunger 5. The feed nut 7 is slidably fitted into the cylinder head 3 of the piston-cylinder device 1 and the top portion 2a of the pusher 2. Reference numeral 10 denotes a feed threaded rod that is provided integrally with the output shaft 9 of the frictionally continuously variable transmission 8 and is fitted into the feed nut 7.

11 is a space between the cylinder head 3 of the piston/cylinder device 1 and the top surface 12 of the presser 2 as a piston, 13 is an oil holding space in the presser 2, and 14 is provided between these spaces. The relief valve 15 is an oil tank. A valve 16 is provided on the flow path that communicates the space 11 between the cylinder head 3 and the top 2a of the presser 2, which serves both for sucking in oil and for returning oil.

As shown in FIG. 1, when the plunger 5 is slidably fitted to the top 2a of the pusher 2 and the relief valve 14 is closed, the oil held in the space inside the pusher 2 is released. It is not possible to move into the space 11 between the cylinder head 3 and the top 2a of the piston. This state is plunger 5
A state in which the presser 2 and the presser 2 are integrated and the oil is introduced into the space 11 through the valve 16 for suction and refilling in the oil tank 15 to start rapid forwarding, that is, the presser 2 depends only on the screw feed. is about to be sent. The force (load resistance) that the pressed object 19 exerts on the presser 2 during rapid forwarding in this state is extremely small, and therefore, during rapid forwarding, the hydraulic pressure in the space 13 inside the presser 2 is sufficient to open the relief valve 14. Not reaching a sufficient value.

When the presser 2 is rapidly forwarded and collides with the object to be pressed, the suction and deflation valve 16 is automatically closed due to the increase in oil pressure in the space 11, and the object to be pressed 1 is automatically closed.
The oil pressure in the space 13 inside the presser 2 increases due to the resistance exerted by the presser 9 on the presser 2 . When this increase in oil pressure exceeds a predetermined value, the relief valve 14 opens and the presser 2
The oil held within can now be moved to the space 11 between the cylinder head 3 and the top 12 of the piston, and the pressure by the booster mechanism that causes the plunger 5 to enter the space 13 within the pusher 2 is started. Ru. When this pressing is performed, the friction continuously variable transmission 8
As the load torque applied to the conical surface increases, the speed change ring 17 of the continuously variable friction transmission 8 automatically moves in the direction of decreasing the rotational speed of the output shaft 9 (in the direction of moving the point of frictional engagement with the conical surface toward the larger diameter side of the conical surface). Move to. The relief valve 14 remains open until the sliding fit between the plunger 5 and the pusher 2 is released and a communication path is formed between the spaces 11 and 13 as shown in FIG. be. That is, the operation of the relief valve 14 is transient. FIG. 2 shows the shape of the pressed object 19 before deformation.
9 is shown in its desired deformed shape.

When the intended pressing of the pressed object 19 is completed, the operating circuit of the electric motor 4 is switched as if the output shaft 9 of the friction continuously variable transmission 8 is reversed, and the oil tank 15 is opened by the lever 20 linked to this switching operation. and piston cylinder device 1
A valve 16 interposed between the two is opened to reset the fast forwarding device. This reset is performed when the plunger 5 is reset to the top 2a of the presser 2 as shown in FIG.
This occurs as a process including a first step in which the pusher 2 comes into a sliding fit, and a second step in which, following the first step, the plunger 5 pulls up the pusher 2 to return it to the state shown in FIG. Note that 21 is an engaging portion that acts when the presser 2 is pulled up.

The oil tank 15, the electric motor 4, and the continuously variable friction transmission 8 can be provided on the side of the piston-cylinder device 1, if necessary, and in that case, the threaded rod 10 is driven via a belt or chain. .

As a continuously variable friction transmission, the speed change range includes the point where the rotational speed of the output shaft is 0, and the rotational speed of the output shaft decreases as the load torque increases.The rotation of the speed change ring is transmitted to the output shaft. There are two types: a "ring rotating type" in which the rotation of the speed change ring is restricted and a "ring non-rotating type" in which the rotation of the orbital ring is transmitted to the output shaft. The friction continuously variable transmission is of the ring rotating type. FIG. 1 shows a cam 22 for moving the speed change ring 17 so as to reduce the rotational speed of the output shaft as the output torque increases, a follower 23 of this cam 11, and a speed change in the direction of increasing the speed of the output shaft 9. A control mechanism is shown including a spring 24 which exerts a force tending to move ring 17.
FIG. 4 shows the outline of the working surface of the cam 22. In this figure, the position of the follower 23 shown by the solid line is the position when the speed change ring 17 selects "high speed", and the position of the follower 23 shown by the dotted line is the position where the speed change ring 17 makes the rotational speed of the output shaft 9 zero. It is.

FIG. 5 is for explaining that the friction continuously variable transmission 8 includes the point where the rotational speed of the output shaft 9 becomes 0 in its speed change range. In this figure, 25 is a conical rotor, 26 is an input A friction transmission wheel on the shaft, 27 is a friction transmission wheel on the output shaft. The friction transmission wheel 26 is frictionally engaged with a transmission surface 28 having an arcuate cross section on the conical rotor 25, and the friction transmission wheel 27 is frictionally engaged with a flat transmission surface 29 on the conical rotor 25. The rotational speed of the output shaft 9 becomes 0 when the speed change ring 17 is moved to the position shown by the solid line and the effective radii a, b,
This is when the relationship a:b=c:d holds between c and d. Note that a is the effective radius of the conical surface, b is the effective radius of the flat transmission surface 29, c is the effective radius of the speed change ring 17, and d is the effective radius of the friction transmission wheel 27. When the cam follower 23 is in the position shown by the solid line in FIG. 4, the speed change ring 17 is in the position shown by the solid line in FIG. 5, and at that time, the load torque applied to the output shaft 9 is shown by T _nax in FIG. Takes a value. On the other hand, when the cam follower 23 is in the position shown by the dotted line in FIG. 4, the speed change ring 17 is in the position shown by the dotted line in FIG.
Take the value indicated by T _h in the figure or a value close to it.

The presser 2 is sent at an extremely high speed corresponding to the load torque T _h until it collides with the object 19 to be pressed. The pressing stroke is performed at a low speed while receiving a large thrust according to the size.

C. Effects of the Invention The pressing device according to the present invention is characterized by "frictionally continuously variable transmission in which the speed change range includes a point where the rotational speed of the output shaft is 0, and the rotational speed of the output shaft is decreased toward 0 as the load torque increases. The machine makes full use of its characteristics to perform fast forwarding and fast reversing, and the power consumed to feed the presser is extremely small. The control system provided in this device is small and can have a simple structure. The pressing device according to the invention has a relatively small overall external dimension and is easy to use.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing one example of a pressing device according to the present invention, FIGS. 2 and 3 are vertical sectional views showing a part of the device shown in FIG. 1 in a different state, and FIG.
, 5 and 6 are drawings for explaining the friction continuously variable transmission provided in the device shown in FIG.
FIG. 4 shows the outline of the control cam, FIG. 5 shows the position of the speed change ring that sets the rotation speed of the output shaft to zero, and FIG. 6 shows the "torque-rotation speed" characteristic of the transmission. DESCRIPTION OF SYMBOLS 1... Piston/cylinder device, 2... Pusher, 2a... Top of pusher, 3... Cylinder head, 4... Electric motor, 5... Plunger, 6... Rotating rod, 7... Feed. Nut, 8...Friction continuously variable transmission, 9...Output shaft, 10...Feed screw rod,
11...Space, 12...Top surface of presser, 13...
Oil holding space in the presser, 14...Relief valve, 15...Oil tank, 16...Valve, 17...
...Speed ring, 18...Communication path, 19...Pressed object, 20...Lever, 21...Engaging portion, 22...
Cam, 23... Follower, 24... Spring, 25...
Conical trochanter, 26, 27...Friction transmission wheel, 28,
29...Transmission surface.

Claims (1)

[Claims] 1. A piston/cylinder device is provided in which a pusher containing oil is used as a piston, and a plunger that is moved in the axial direction by a screw feed is slidably fitted into the cylinder head of the piston/cylinder device and the top of the piston. , the diameter of the oil holding space of the pusher is made larger than the diameter of the plunger, and the slidable engagement of the plunger with the top of the piston cylinder device is released, so that the oil holding space of the pusher becomes larger than the diameter of the plunger. A relief valve is provided that opens when the oil in the presser exceeds a predetermined value during the transition period until the space between the cylinder head of the cylinder device and the top surface of the piston reaches a state where it communicates with the space between the cylinder head of the cylinder device and the top surface of the piston to effect the above-mentioned communication. , an oil tank for supplying oil between the cylinder head and the top surface of the piston of the piston/cylinder device and receiving oil discharged from the space is provided, and the piston/cylinder is placed in the oil holding space in the pusher. The flow between the tank and the piston/cylinder device is controlled by a suction/return system, which is closed when the plunger of the device enters, and is open when the plunger moves integrally with the piston for fast forwarding and fast reversing. The above-mentioned screw feed drives a friction continuously variable transmission which is placed on the road and whose speed range includes a point where the rotational speed of the output shaft is 0, and the rotational speed of the output shaft is decreased toward 0 as the load torque increases. A hydraulically operated pressing device characterized by being provided on the system.