JPH0242598B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for preventing floating punches from floating in powder forming presses.

(Prior art) In general, when molding using a powder molding press, while preventing cracks from forming in the molded product after pressurization,
It is important to extrude this from within the die. In other words, in a typical forming press, the die plate is pushed down after the upper punch rises, but if the float punch floats up during this process, the die and molded product are compacted. Due to the residual force, frictional force is generated at both joints, so when a molded product with a flange is extruded after molding, a crack 102 is generated at the joint between the flange 100 and the boss 101. (See Figure 8a). In addition, when extruding a pot-shaped molded product after molding, at the joint between the bottom part 103 and the boss part 104,
A crack 105 occurs (see FIG. 8b).

For this reason, powder molding presses are now equipped with floating prevention devices for the float punch in order to prevent the above-mentioned cracks from occurring. ) was configured to balance the fluid by putting it in the opposite direction. This is because when the number of moldings per minute is high, a time lag occurs from when the balance pressure is applied to the filling cylinder until the balance is achieved. This is because it takes time to switch the valve and reach the specified pressure. Also, depending on the shape of the product, the number of moldings may be changed. In this case, the valve switching timing must be changed. This also applies when releasing pressure from the cylinder described above. As described above, the conventional anti-floating device for powder molding presses has the problem of having to change followability during high-speed rotation and the timing when changing the rotation speed. For this reason, depending on the shape of the molded product, cracks as described above often occur unless fine adjustments are made when the speed is increased.

In addition, there is Japanese Patent Publication No. 57-37440 which improves the above-mentioned problems. This floating prevention device has a "wedge" placed outside the side of the extrusion plate that directly suppresses the floating of the extrusion plate from the side when pressure is applied by operating a cylinder. The structure was such that the float punch was balanced by the action of the "wedge" even during the descending process. Therefore, before the upper punch enters the pressurizing process (at the start of the powder filling process), the anti-floating mechanism starts operating, and
In the process where the upper punch reaches the pressurization completion position (at the point when the float punch side also needs upward force for pressurization), even if the upper punch enters the descending process for pressurization, there is no upward force on the float punch side. As a result, the float punch easily descends due to the pressing force of the upper punch, and the powder on the boss portions 101 and 104 is transferred to the flange portion 10 during powder compaction.
0, it flowed to the bottom 103 and the desired good product could not be obtained.

(Object of the Invention) The present invention solves the problems of the prior art described above. In other words, an object of the present invention is to prevent the floating punch from floating from the time when the upper punch reaches the pressure completion position to the time when the upper punch moves to the extrusion completion position. Since the float punch has a certain rising force, the powder at the boss part flows to the flange side during molding, eliminating defective molded products with cracks caused by unbalanced density, and ensuring that good powder molding is always possible. An object of the present invention is to provide a device for preventing floating of a powder molding press.

(Structure of the Invention) In order to achieve the above object, the powder molding press of the present invention has a cam fitted to the main shaft, a push-down bar that is suspended from a push-down plate that moves up and down in conjunction with the cam, and , a first fluid cylinder connected to the push-down plate and urging the push-down plate downward; a second fluid cylinder disposed below the push-down rod; The balance between the first fluid cylinder and the second fluid cylinder is configured to prevent the float punch connected to the second fluid cylinder from floating up.

(Function) In the floating prevention device with the above configuration, even when the upper punch enters the pressurizing process, at this point the operating section of the cam fitted to the main shaft does not reach the position to lower the push-down plate. Therefore, the push-down rod hanging down from the push-down plate does not descend together with the upper punch. Therefore, when the upper punch still descends to compress the powder in the die, the float punch is not restrained by the anti-floating device, so that the upper punch can apply pressure. When the upper punch descends with the die in this state and enters the pressurizing process, it is urged downward by the first fluid cylinder by the action of the operating section of the cam attached to the main shaft. In order to lower the push-down plate, which is connected to the cam, the push-down rod that is suspended from the push-down plate starts to descend. At this time, the push-down rod presses the upper part of the second fluid cylinder disposed below the push-down rod, thereby balancing the forces between the first fluid cylinder and the second fluid cylinder. . Therefore, when the pressurization process of the upper punch is completed, the float punch connected to the second fluid cylinder is pressed downward by the push-down rod, so that the float punch is not pressed during the pressurization process of the upper punch. Having a rising force, it is possible to smoothly and completely prevent problems such as powder flowing from the boss side to the flange side during powder molding or cracks occurring during extrusion after molding.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

As shown in FIGS. 1 to 3, a main shaft 2 including a crankshaft is rotatably supported on the upper part of a machine frame 1, and this main shaft 2 is connected to a drive source (see FIG. 3) via a reduction gear mechanism (not shown). (not shown). An upper ram 4 is connected to the central crankshaft portion of the main shaft 2 via a pitman screw 3 so as to be movable up and down. An upper punch 6 is fixed to the upper ram 4 via a punch plate 5. Further, a die plate 9 having a die 10 housed in the center thereof on the same surface is fixedly connected to a rod 8 erected on the circumferential surface of the pull-down plate 7. A plurality of extrusion screws 11 are inserted into the lower surface of the die plate 9 so as to be vertically adjustable. A core rod 13 is erected at the center of the pull-down plate 7 so as to penetrate through the center hole of the fixing plate 12 on the machine frame 1. A second core rod 13 protrudes above the fixed plate 12.
A punch 14 is loosely fitted. Further, a stopper 35 is attached around the second punch 14 on the fixed plate 12.

Next, on the diagonal circumferential surface of the fixed plate 12, fluid cylinders 26, 26, which are the main parts of the floating prevention device 20 to be described later, are installed for each piston rod 2.
The rods 26a are arranged vertically so that they can be moved up and down by screwing them into a member on the fixing plate 12, with the rods 6a facing downward. The cylinders 26, 26 have a float plate 32 at the outer peripheral portion 3.
The arms 15a are connected to each other so as to be able to move up and down integrally through an arm 15a that protrudes upright from the arm 15a. The float plate 32 has a rod 1 with a roller 15c on its periphery.
5b is housed so as to be elastically movable up and down by the support of a spring, etc., and the holder 15 holds the second punch 1.
4, and in this case, the threaded part provided on the circumferential surface of the central cylindrical part of the holder 15 is screwed into the internal threaded part provided on the inner diameter surface of the peripheral part of the float plate 32 so as to be movable up and down. The central cylindrical portion is assembled with a nut 16 in such a manner that it can be adjusted up and down. A first punch 18, which is interposed between the die 10 and the second punch 14 and forms the flange portion of the powder molded product X, is concentrically fitted to the second punch 14 on the upper surface of the center of the holder 15. It is mounted and fixed so that it can be raised and lowered as a whole. Here, the float punch 33
The first punch 18, the holder 15, the float plate 32, the arm portion 15a, and the cylinder outer peripheral portion 34
It consists of Further, although this configuration is for molding a flanged molded product, it is also possible to mold a pot-shaped molded product by adopting a so-called hairpin configuration.

Furthermore, the above-mentioned pull-down plate 7 has a machine frame 1
The lower ram 19 is slidably supported in the vertical direction.
The lower rams 19 are connected to each other by a screw connecting member or the like, and the filling cylinders 17, 17 are connected to each other via a base flange member fixed to the lower ram 19. Therefore, the lower ram 19 is moved up and down by the operation of the filling cylinders 17, 17. A compression cam 27 and a pressure cam 28 having mutually different phases are fitted into the shaft end of the main shaft 2, and the compression cam 27 and the pressure cam 28 are slidable vertically by the machine frame 1. The compression rod 2 is urged upward by a spring member (not shown) in a supported state.
9. Rollers 101, 1 at each upper end of the extrusion rod 30
02, each rod 29, 30 is pressed downward when the main shaft 2 rotates. Note that 31 is an adjustment member for adjusting the lower limit of the compression rod 29.

The powder molding press according to the above embodiment is equipped with a floating prevention device 20 shown below. This floating prevention device 20 is constructed as follows. In other words, as shown in FIGS. 1 to 4, on both sides of the shaft near the central belt of the main shaft 2, in which the Pittman screw 3 is fitted to the crankshaft in the central belt, there is a part of the peripheral edge of the disk surface. The cams 23, 23, which have an operating section 23a formed by gradually deepening the arc, are connected to the main shaft 2.
It is fitted with a shaft so that it can rotate freely. Directly above the cams 23, 23 is a roller 22 that rotates by slidingly contacting the cam 23 at each position on the lower surface.
a, 22a arranged thereon, the piston rod 21 of a fluid cylinder 21 as a first fluid cylinder placed on the center top surface of the machine frame 1.
It is disposed so that it can be raised and lowered while being supported by a. In this case, a push-down rod 25 having a length that reaches near the die plate 9 is vertically provided from the lower surface of the diagonal corner of the push-down plate 22. The push-down rod 25 is formed into a rod shape, and a guide rod 24 extending penetratingly from the top surface of the machine frame 1 is loosely inserted into the center thereof. Therefore, the push-down rod 25 is configured to be able to move up and down normally by being supported by the guide rod 24.

Further, below this push-down rod 25, fluid cylinders 26, 26 as a second fluid cylinder constituting a part of the float punch are arranged so that each piston rod 26a faces downward. It is disposed vertically so that the members on the fixed plate 12 can be moved up and down. The fluid cylinder 21 and the fluid cylinder 26 are equipped with a tank and a pressure reducing valve so that the pressure inside the cylinder can be adjusted.
As described above, the float plate 32 is connected to the cylinders 26, 26 so as to be able to move up and down integrally through the arm portion 15a that projects upright from the outer periphery. The floating prevention device 20 configured as described above operates on the roller 22a as follows. Since the push-down rod 25 does not descend unless the operating section 23a of the cam 23 comes into contact with it, the second cylinder 26 waits at the powder W filling position (the position shown in FIG. 1). Next, when the operating section 23a of the cam 23 reaches the position of the roller 22a, as shown in FIG. do. At the time when the pressurization process by the upper punch 6, the first punch 18, and the second punch 14 is completed (pressure completion position F in the stroke diagram in FIG. 7), the fluid cylinder 26 of the floating prevention device 20 is pushed downward. Since the float punch 33 presses down due to the force balance with the fluid cylinder 21 under the pressure of the rod 25, floating of the float punch is prevented from this point until the extrusion completion position G of the powder molded product X is reached. It is configured so that it can be done.

The operation of the floating prevention device 20 having the above structure will be explained using the stroke diagram in FIG. 7.

First, at the filling position shown in FIG. 1, the upper punch 6 starts to descend along the A curve by the upper ram 4.
When the upper punch 6 is inserted into the die 10, the powder W previously filled in the die 10 at the filling position E (position at 30 degrees) is preliminarily compressed. After this preliminary compression, the die 10 and flow punch 33 are also lowered in conjunction with the lowering of the upper punch 6, as shown by lines B and D, thereby performing compression.

Next, the upper punch 6 is attached with the first punch 18.
When the pressurizing process for the powder W has progressed by dropping down more than the first punch 18,
As shown in FIG. 4, since the operating section 23a of the cam 23 reaches the position of the roller 22a, the cam 23 is interlocked with the cam 23 and is suspended from the push-down plate 22, which is pressed downward by the fluid cylinder 21. The push-down rod 25 begins to descend along line C. In this case, the pushing down bar 25 preferably applies a pushing operation from above to the fluid cylinder 26 disposed directly below the pushing down bar (see FIG. 2). That is, in the state shown in FIG. 2 where the pressurization process by the upper punch 6, the first punch 18, and the second punch has been completed (pressure completion position F in FIG. 6), the outer periphery of the fluid cylinder 26 is Part 34
, a float punch 33 composed of a float plate 32 connected to the outer peripheral part 34 via an arm part 15a, a holder 15, and a first punch 18 mounted on the holder 15.
is held down by the balance of forces between the fluid cylinders 21 and 26, so even if the upper punch 6 immediately enters the rising process as shown in FIG. 7, the float punch 33 is prevented from floating in coordination. This can be easily and reliably prevented.

Further, even if the upper punch 6 rises after the completion of pressurization, the floating prevention operation for the float punch 33 by the floating prevention device 20 continues until the extrusion completion position G of the powder molded product X, and this period is the floating prevention zone. It becomes H. Therefore, during pressure molding of powder W,
This powder W does not flow from the boss side to the flange side. Further, the slide block 36 of the float plate 32 comes into contact with the stopper 35, so that the float plate 32 stops and the pressurized position becomes constant. Conventionally, when the thickness of the flange part changes depending on the powder molded product X, adjustment has been made by changing the stopper 35. In this case, adjustment was difficult because the position of the upper surface of the fluid cylinder 26 also changed, but since the nut 16 was rotated to move the holder 15 up and down, and thereby the first punch 18 was moved up and down, it was possible to Even if the product X changes, there is no need to adjust the position of the fluid cylinder 26. Although the push-down bar 25 has been described so far as coming into contact with the fluid cylinder 26 located directly below, the push-down bar 25 may be configured to come into contact with any part of the float punch 33. In addition, in addition to the push-down bars 25 arranged diagonally on the push-down plate 22, if other push-down bars are arranged at positions opposite to the positions 24 and 24, a plurality of float punches can be arranged. can.

(Effects of the Invention) As described above, the present invention has a cam fitted onto the main shaft of a powder molding press, which moves up and down in conjunction with the cam.
A push-down rod is suspended from the push-down plate that is urged downward by a first fluid cylinder, and a second fluid cylinder connected to a float punch is disposed below the push-down rod, and a cam Due to the balance between the forces of the first fluid cylinder and the second fluid cylinder, the float punch is lifted from the top from the time the punch reaches the pressurization completion position to the time it moves to the extrusion completion position. It is characterized by the fact that it has been prevented. Therefore, in the descending stroke of the upper punch, even if it receives the pressing force of the upper punch, the float punch has a rising force, so the powder does not flow from the boss side to the flange side, and the density is balanced, thereby preventing cracks, etc. It is possible to eliminate defective products that have.

[Brief explanation of drawings]

The drawings show one embodiment of the invention.
The figure is a partially longitudinal front view of the powder molding press and anti-floating device at the filling position, Figure 2 is a partially longitudinal front view of the same at the pressurization completion position, and Figure 3 is a partially longitudinal front view of the same at the extrusion completion position. Front view, Figure 4 is the 2nd
A front view of the floating prevention device along the - line in the figure,
Figure 5 is a front view showing the arrangement of the push-down plate and push-down rod along the same line, Figure 6 is an enlarged longitudinal sectional view of a part of the powder molding press, and Figure 7 is a view of each punch during powder molding. A stroke diagram showing the operational relationship of the anti-float device, and FIGS. 8a and 8b are vertical cross-sectional views of a molded product molded by a conventional powder molding press. Explanation of symbols 2...Main shaft, 14...Second punch, 1
8...first punch, 21...first fluid cylinder, 2
2... Push-down plate, 23... Cam, 25... Push-down rod, 26... Second fluid cylinder, 33... Float punch.

Claims (1)

[Claims] 1. In a powder molding press, a cam is fitted onto the main shaft, a push-down bar is suspended from a push-down plate that moves up and down in conjunction with the cam, and the push-down bar is connected to the push-down plate and moves up and down. the first which urges the plate downward;
A fluid cylinder is disposed, and a second fluid cylinder is disposed below the push-down rod, and the balance between the forces of the first fluid cylinder and the second fluid cylinder by the operation of the cam causes the second An anti-floating device for a powder molding press, characterized in that it prevents a float punch connected to a fluid cylinder from floating. 2. The powder according to claim 1, wherein the second fluid cylinder is connected to a float punch so that the pressurized position applied by the first fluid cylinder is constant. Anti-floating device for molding presses.