JP2585046B2 - Knockout upper limit holding hydraulic circuit for bottom knockout device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bottom knockout device for pushing out a molded product in a mold from the bottom of the mold, and more particularly to a knockout upper limit for holding a knockout pin after knockout at an upper limit position. It relates to a holding hydraulic circuit.

(Prior art) Fifth example of a knockout device in a forging press
The outline will be described with reference to the drawings. An upper cam 1 is fixed to a wheel shaft or a crankshaft of an eccentric wheel for operating a forging press piston, and a lower lever 6 is connected via a rod 4 to the other end of an upper cam lever 3 that follows the upper cam 1. A lower cam 9 is fixed to the cam shaft 8 directly below the mold. A plurality of knockout pins 11 are arranged on the knockout lever 10, and the knockout pins 11 move into and out of the bottom of the press die 20 by swinging of the lower cam 9 via the knockout lever. The lower lever 6 is fixed to the cam shaft 8 of the lower cam 9. By adjusting the spacer or the turnbuckle 5 interposed in the intermediate portion of the rod 4, the length of the rod 4, that is, the lower lever 6 and the cam shaft 8,
The swing angle of the lower cam 9 is changed, and the stroke amount of the knockout pin 11 is adjusted. After knocking out, it is necessary to hold the knockout pin 11 at the stroke end of the knockout pin 11, that is, the knockout upper limit position for a certain period of time.For this reason, conventionally, an upper limit holding cylinder device 24 is provided below the tip of the knockout lever 10 below. , The cylinder device 24 biases the knockout lever at the upper limit position.
10 is supported from below by a piston rod 25.
In order to change the stroke for holding the knockout upper limit in accordance with the stalk adjustment of the knockout pin 11, adjust the adjustment screw 28 that contacts the tip of the piston rod to the knockout lever 10
The effective stroke of the cylinder device 24 was changed by adjusting the length of the adjusting screw 28 projecting downward.

(Problem to be Solved by the Invention) In the conventional bottom knockout device described above,
Adjustment of the knockout upper limit holding position is performed by adjusting the effective stroke of the cylinder device that pushes up the tip of the knockout lever, but this work must be performed every time the stroke of the knockout pin is changed, and the forging press is operated several times. Since the operation is performed while adjusting the predetermined stroke while operating the adjusting screw, there is a disadvantage that much time and labor are required.

An object of the present invention is to provide a knockout upper limit holding hydraulic circuit that can secure a desired knockout upper limit holding by following the stroke amount of the knockout pin without any need to adjust the upper limit holding cylinder device even when the stroke of the knockout pin is changed. is there.

(Means for Solving the Problems) The present invention provides an upper cam fixed to a crankshaft or an eccentric shaft, an upper cam lever following the upper cam, and a lower cam lever connected to one end of the upper cam lever via a rod. Lever and
In a bottom knockout device having a lower cam fixed to a shaft of the lower lever, a knockout lever following the lower cam, and a knockout pin fixed to the knockout lever, a tip end of the knockout lever includes two rod hydraulic cylinders. A pilot check valve is interposed in a reciprocating pipe connecting a piston rod and connecting a cylinder chamber of the hydraulic cylinder and an electromagnetic switching valve so as to allow pressure oil to flow into the cylinder chamber, respectively. A check valve and a pilot check valve are interposed in series on the bypass pipes connecting the pipes so as to prevent pressure oil from flowing out of the adjacent outgoing pipes or return pipes. Connect the pilot port of the pilot check valve provided on one of the pipes through the pilot line. And a pilot check valve provided on the other pipe of the outward or return path and a pilot check valve provided on the bypass pipe connected to a pilot pressure source via an electromagnetic switching valve, By switching the electromagnetic switching valve, the piston rod is held at the upper limit position for forcibly rising by the knockout lever for a predetermined time.

(Examples) Next, the present invention will be described with reference to the drawings with respect to examples.

FIG. 1 is a diagram showing a knockout upper limit holding hydraulic circuit according to an embodiment of the present invention. FIG. 2 is a schematic view of a bottom knockout device having a knockout pin stroke adjustment mechanism applied to the present invention. Referring to FIG. 2, an upper cam 1 is mounted on an eccentric shaft 21 of a piston (male type) at a position outside the frame of the forging press, and is engaged with the upper cam 1 via a cam roller 2 so that the upper cam 1 The upper cam lever 3 is driven by the outer side of the frame. A rod 4 extending vertically downward is pivotally attached to the other end of the upper cam lever 3.
Is pivoted. A plurality of knockout pins 11 are arranged on the substantially horizontal knockout lever 10 on the lower side of the press mold 20 so as to be able to enter and exit the bottom of the mold, and the knockout lever 10 is driven so that the lower surface thereof contacts the lower cam 9. It is pivotally attached to the frame of the press body. A double rod hydraulic cylinder 30 is provided below the knockout lever 10, and a piston rod 31 of the hydraulic cylinder 30 is pivotally attached to the tip of the knockout lever 10. Double rod hydraulic cylinder
The upper and lower cylinder chambers 30a and 30b on both sides of the piston 30 have the same effective sectional area. And the upper cylinder chamber 30a
The lower cylinder chamber 30b is connected to a hydraulic circuit described later, as shown in FIG. The cam shaft 8 of the lower cam 9 is supported by the frame, and the lower lever 6 is fixed to the other end.

As shown clearly in FIG. 2, the lower lever 6 is centered on the pivot point a between the upper lever 3 and the rod 4 and has a camshaft 8.
An arc-shaped groove 6b extending in a direction substantially perpendicular to the groove is formed, and a slider 7 at the lower end of the rod is slidably fitted in the arc-shaped groove 6b. In FIG. 2, R1 and R3 are arc-shaped grooves 6
The radius b of the groove wall, R2, is the radius of the center of the groove, and both are centered on the point a at the upper end of the rod 4. A bracket 6a protrudes from the lower lever 6, and a bracket 7a protruding downward and outside the lower lever 6 is also formed on the slider 7.
Screw lock cylinder 15 between both brackets 6a, 7a
Is installed. A slider driving screw 12 is pivotally mounted on a bracket 7a of the slider 7, and a worm gear 13 is supported by the bracket 6a of the lower lever 6 so as to be unable to move in the axial direction. The worm gear 13 has a threaded hole formed in the center thereof, and the screw 12 for driving the slider is connected to the lower lever 6.
And is screwed into the screw hole of the worm gear 13. The worm gear 13 is rotated while engaging with the worm 26 of the output shaft of the slider drive motor 14 when the stroke of the knockout pin 11 is adjusted.

Next, the hydraulic circuit of the double rod hydraulic cylinder 30 will be described with reference to FIG. The upper and lower cylinder chambers 30a, 30b of the double rod hydraulic cylinder 30 are connected to a hydraulic power source 43 via pipes 22a, 22b and a first electromagnetic switching valve 41. Therefore, by selectively switching the electromagnetic switching valve 41 in FIG. 1, the supply of the hydraulic pressure to the upper cylinder chamber 30a and the supply of the hydraulic pressure to the lower cylinder chamber 30b are switched (the piston rod 31).
Up and down).

Hereinafter, for convenience of explanation, a pipe 22b connected to the lower cylinder chamber 30b is referred to as an outward pipe, and a pipe 22a connected to the upper cylinder chamber 30a.
Is called a return pipe. Outgoing piping 22 of the hydraulic cylinder 30
b and the return pipe 22a are connected to the hydraulic cylinder from the switching valve 41 side, respectively.
Pilot check valves 39 and 38 are provided to allow the hydraulic pressure to flow into the 30 side. Further, in the bypass pipe 45 connecting the forward pipe 22b and the return pipe 22a, the inflow of pressurized oil from the forward pipe to the return pipe is prevented in order from the forward pipe 22b, and the reverse is allowed. A check valve 37 and a pilot check valve 36 for permitting the flow of pressure oil from the outgoing pipe side to the return pipe side and preventing the reverse flow are interposed in series. The second electromagnetic switching valve 44 supplies and discharges pilot pressure to and from the pilot check valves 36 and 38. One end of the second electromagnetic switching valve 44 is connected to the hydraulic pressure source 43, and the other end is connected to the pilot line via pilot lines 46a and 46b. It is connected to the pilot ports of check valves 36 and 38.

Therefore, by selectively switching the second electromagnetic switching valve 44, when pilot pressure is supplied to one of the pilot check valves 36 and 38 (the check valve is opened), the pilot pressure is not supplied to the other (the check valve is closed). As it is). A return port 22 is connected to the pilot port of the pilot check valve 39 interposed in the outgoing pipe 22b.
A pilot pipe 40 branching from a is connected, and when pressurized oil is supplied to the return pipe 22a (downward movement of the piston rod 31), the pilot check valve 39 is opened using a part of the pilot pressure as pilot pressure, and the outgoing pipe 22b is opened. The hydraulic cylinder 3
This allows the oil to flow from the 0 side to the tank (first electromagnetic switching valve 41). Reference numerals 33 and 32 denote relief valves, which are provided in pipes branched from the outgoing pipe 22b and the return pipe 22a, and are relieved when abnormal pressure is applied to the respective pipes 22b and 22a, and discharged to the tank. I do. Also, 35,34
Is a check valve, similar to the check valves 33 and 32,
Both pipes are connected to pipes branched from the outgoing pipe 22b and the return pipe 22a.
It is provided so as to prevent outflow of pressure oil from 22b, 22a, and supplies oil from the tank to the respective pipes 22b, 22a when both pipes 22b, 22a become negative pressure. Reference numeral 42 denotes a pressure reducing valve provided before the first electromagnetic switching valve 41 (on the hydraulic pressure source 43 side).

Here, the solenoid number of the first electromagnetic switching valve 41 is SV-A on the left side and SV-B on the right side, and the solenoid number of the second electromagnetic switching valve 44 is SV-A on the left side.
Table 1 shows the switching form of each switching valve in this embodiment, where C and the right side are SV-D.

In the above table, ○ indicates that the valve portion is in the open state, and × indicates that the valve is in the closed state.

In the above configuration, the slider 7 is fixed to the lower lever 6 by the screw lock cylinder 15, and follows the swing of the upper cam 1 interlocked with the vertical movement of the piston of the forging press. 4, the lower lever 6 swings, and the knockout pin 11 moves in and out of the bottom of the mold due to the swinging of the lower cam 9 via the cam shaft 8 to perform a knockout operation of the forged product (FIG. 2). When the knockout lever 10 is raised during the knockout operation, the piston rod 31 of the two-rod hydraulic cylinder 30 connected thereto is forcibly raised.
At this time, the pilot check valve 36 is opened by setting the electromagnetic switching valves 41 and 44 to the state shown in Table 1 (1). At this time, since the pilot check valves 38 and 39 are kept closed, the outflow of pressurized oil from the forward and return pipes 22b and 22a to the tank is prevented, and the return pipe 2
The pressure oil returned to 2a returns to the lower cylinder chamber 30b via the outgoing pipe 22b through the bypass pipe 45 and the pilot check valve 36 as shown by the dashed arrow. As described above, since the effective sectional areas of the upper and lower cylinder chambers 30a and 30b are the same, there is no need to externally replenish the hydraulic oil.

Next, at the knockout stroke upper limit position, the solenoid
When 41 and 44 are switched to the state of II in Table 1, the upper cylinder chamber 30a is blocked because the pilot check valves 36 and 38 are closed, and the lower cylinder chamber 30b is connected from the hydraulic pressure source 43 to the first electromagnetic switching valve. 41, a state in which hydraulic pressure is applied via the pilot check valve 39, and both rod hydraulic cylinders 30 are stopped while being maintained at the piston rod upper limit position. From this state, even if the lower cam 9 rotates downward as shown in FIG. 3 and returns to the original position, the state shown in Table II is maintained for a predetermined time, so that the knockout lever 10 and the knockout pin 11 are held.
And the forged product is held at the upper limit position. After the forged product is taken out, the state is switched to the state shown in Table III, whereby the upper cylinder chamber 30a is supplied with hydraulic oil from the hydraulic power source 43 via the first electromagnetic switching valve 41 and the pilot check valve 38, Since a part of the oil is used as the pilot pressure to open the pilot check valve 39 of the outward piping 22b, the return pressure oil from the lower cylinder chamber 30b is returned to the tank port via the pilot check valve 39 and the first electromagnetic switching valve 41, The knockout lever 10 descends to a position where it contacts the lower cam 9.

Here, in the present invention, even when the timing of switching from the forced rise of the piston rod 31 to the holding of the upper limit varies somewhat, it is possible to reliably stop and hold at the stroke rising end of the knockout pin.

Therefore, for example, the upper limit holding switching timing at the time of rising is early, and even if abnormal pressure is generated in the upper cylinder chamber 30a, the pressure oil is relieved from the relief valve 32. Conversely, even if the timing is delayed and the hydraulic oil in the lower cylinder chamber 30b becomes insufficient (negative pressure), the insufficient oil is replenished from the tank by the action of the check valve 35 or the pilot check valve 39.

Here, when changing the stroke amount of the knockout pin 11, the screw 12 is extended by the screw feed action of the worm gear 13 and the screw 12 by releasing the screw lock cylinder 15 and driving the motor 14 in FIG. The slider 7 slides along the arc-shaped groove 6b of the lower lever 6, and the swing fulcrum of the lower lever 6, that is, the distance L between the cam shaft 8 and the slider 7 changes. Thereafter, when the slider 7 is fixed to the lower lever 6 again by the screw locking cylinder 15, the lower lever 6 which is swung by the rod 4 is moved.
The arm length of the lower lever 6, the swing angle of the lower shaft 6, the cam shaft 8 and the lower cam 9, that is, the knockout pin
The stroke amount of 11 is adjusted. If the stroke of the knockout pin 11 according to the present embodiment is shown in a knockout diagram, the stroke amount changes as shown by the cycloid curves A, B, and C without delaying the knockout start point, as shown in FIG. Accordingly, the upper limit holding stroke is
Follows like e and f. As described above, according to the present invention, it is not necessary to adjust the upper limit holding cylinder unlike the related art, and the knockout pin can be held at the same stroke upper limit position by following an arbitrarily set stroke amount.

(Effects of the Invention) As described above, according to the present invention, the knockout lever is connected to the two-rod hydraulic cylinder, the piston rods of the two-rod hydraulic cylinders are forcibly raised, and the hydraulic circuit of the cylinder is switched. Since the piston rod is held at the rising end, even when the knockout stroke amount is adjusted, the operation of adjusting the upper limit holding stroke is unnecessary, and efficient operation can be secured.
Even if the timing of switching the hydraulic circuit is not so strict, there are many advantages such as not affecting the operation of holding the knockout upper limit.

[Brief description of the drawings]

FIG. 1 is a diagram showing a knockout upper limit holding hydraulic circuit according to an embodiment of the present invention, FIG. 2 is a schematic diagram of a knockout pin stroke adjusting mechanism of a bottom knockout device applied to the present invention, and FIG. Partial schematic diagram of the bottom knockout device in a knockout upper limit holding state,
FIG. 4 is a diagram showing knockout characteristics in the present invention, and FIG. 5 is a schematic diagram of a conventional knockout device. 9 Lower cam, 10 Knockout lever, 11 Knockout pin, 30 Double rod hydraulic cylinder, 31 Piston rod, 32, 33 Relief valve, 34, 35, 37 Check valve, 36, 38, 39: pilot check valve, 40, 46a, 46b: pilot line, 41: first electromagnetic switching valve, 44: second electromagnetic switching valve.

Claims (1)

(57) [Claims] An upper cam fixed to a crankshaft or an eccentric shaft; an upper cam lever following the upper cam; a lower lever connected to one end of the upper cam lever via a rod;
In a bottom knockout device having a lower cam fixed to a shaft of the lower lever, a knockout lever that follows the lower cam, and a knockout pin fixed to the knockout lever, the tip of the knockout lever has two rod hydraulic cylinders at the tip end. A pilot check valve is interposed in a reciprocating pipe connecting a piston rod and connecting a cylinder chamber of the hydraulic cylinder and an electromagnetic switching valve so as to allow pressure oil to flow into the cylinder chamber, respectively. A check valve and a pilot check valve are interposed in series on the bypass pipes connecting the pipes so as to prevent outflow of pressurized oil from the adjacent outgoing pipes or return pipes. Connect the pilot port of the pilot check valve provided in one of the pipes through the pilot line. The pilot port of the pilot check valve provided on the other pipe of the outward or return path and the pilot port of the pilot check valve provided on the bypass pipe are connected to a pilot pressure source via an electromagnetic switching valve while being connected to the other pipe. Knockout upper limit holding hydraulic circuit.