JP2838477B2 - Powder molding method and apparatus for stepped molded articles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder molding method and a powder molding apparatus for a stepped molded product having one end face flat and the other end face stepped.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 11 (a) and 11 (e), molding of a molded article 100 having a flat one end surface and a stepped other end surface usually includes a flat surface 101 on an upper surface side and a stepped surface. It is general that the attachment surface 102 is formed so as to face the lower surface.

That is, as shown in FIGS. 11A and 11B, when the powder 104 is filled in the die hole 103, the powder 1
Since the upper end surface of the flat powder 04 is a flat surface that matches the upper surface of the die 105, the upper surface of this filling powder is set as the flat surface side, and a plurality of lower punches 106 and 107 are provided for each step. The step surface 102 was formed.

As shown in FIG. 10, an upper punch 108 is fixed to an upper ram 109, an outer lower first punch 106 is movably supported by a fluid pressure cylinder 112, and an inner lower second punch 107 is fixed to a fixed plate. 111. Then, the upper punch 10 is moved by the upper ram 109.
8 is moved downward to pressurize the powder 104, the lower first punch 106 is moved downward by the balance between the pressing force and the supporting force of the fluid pressure cylinder 112, and the lower first punch 106 is moved when the final pressing is completed. The molded product 100 is formed into a predetermined size by being positioned by the stopper mechanism 113.

[0005] The stopper mechanism 113 is provided with the lower first punch 10.
Sliding block 11 slidably provided along the lower surface of lower first punch plate 114 supporting
5 and a stopper 116 that stands on the fixed plate 111 and contacts the sliding block 115 from above when pressing is completed.

Further, the molded article 100 is pulled out from the die hole 103 by lowering the die 105, and the extracted molded article 100 is conveyed by sliding the upper surface of the die 105, and the process proceeds to a powder filling step for the next molding. .

In order to remove the molded product 100, it is necessary to release the stopper mechanism 113 and move the die 105 downward. Therefore, the downward movement of the die 105 causes the sliding block 115 to move laterally. A stopper release mechanism 117 is provided. The stopper release mechanism 117 includes a release pin 118 provided on the lower first punch plate 114 so as to be vertically movable,
A wedge 119 which is provided at the lower end of 8 and converts the vertical movement of the release pin 118 into a lateral movement of the sliding block 115; a pusher 121 fixed to the die plate 120 and pressing the release pin 118 by the downward movement of the die plate 120; , Is composed of.

[0008]

However, in the case of the above-mentioned prior art, the filling depth of the powder 104 is determined by the molding 1
Although the ratio of the step portions 102a and 102b is the same so that the final molded product is formed with a uniform density, when the lower first punch 106 descends, first, the upper punch 108 and the outer Since the powder portion between the lower first punches 106 is compressed, the powder near the center lower second punch 107 moves and falls onto the lower second punch. Next, when the upper punch 108 and the lower first punch 106 are simultaneously lowered, the powder on the lower second punch 107 is returned to the lower first punch 106 side.
However, there is a problem in that the particles move and are not pressed to a uniform density, and shrink during sintering to cause distortion and cracks (see FIG. 11 (f)).

In particular, in the case of a very thin molded product as shown in FIG.

Further, in order to support the pressing force when the pressurization is completed, a certain amount of engagement allowance d is required between the sliding block 115 and the stopper 116 (FIG. 10B).
), There is also a problem that if the molded article 100 is extremely thin, the engagement allowance d cannot be secured. That is, the molded article 100
The extraction stroke corresponding to the thickness of the wedge 11
Since the horizontal movement of the sliding block 115 is converted via the block 9, if the molded product 100 is thin, the engagement allowance d cannot be sufficiently obtained. However, in order to receive the pressing force, a certain amount of engagement allowance d is required at a minimum, and the engagement allowance d cannot be sufficiently secured with an extremely thin molded product.

It is sufficient to change the angle of the wedge 19 to increase the rate of conversion of the horizontal motion. However, there is a restriction on the pushing force of the pusher, and the angle is usually set to about 45 degrees.
As an example, for a 100 ton press, wedge 119
With the lower stroke c = 15 [mm] and the allowance d = 14
[Mm] is required, but the die filling amount is 4 [mm]
In this case, c = 4 [mm] and d = 3 [mm], and a large load cannot be received.

Further, when the molded article 100 is conveyed after being extracted, for example, if the stepped portion 102b protrudes on the lower surface side, the molded article 100 is unstable and easily broken, so that the molded article 100 is turned upside down in the subsequent conveying step. And a reverse rotation mechanism is required, the apparatus configuration becomes complicated, and the number of steps increases. Therefore, there is a demand for a molding method in which the flat surface 101 becomes the lower surface side in the molding stage.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to accurately compress without a variation in density, to eliminate the need for a mechanism for releasing a stopper, and to convey the transfer. It is an object of the present invention to provide a method and an apparatus for powder molding of a stepped molded product having good flexibility.

[0014]

In order to achieve the above object, the present invention is to form a stepped molded product having at least one end surface having a stepped shape having a plurality of steps.
A plurality of punch sets are prepared with a pair of upper and lower punches corresponding to each step of the molded product, and the powder filled in the die hole is prepared for each.
Pressing is performed by the upper and lower punches of the punch set to form a stepped shape.
In the powder molding method stepped molded article shape, such that the density of each powder portion is pressurized by the punch assembly is always the same, at the same time pressurized powders portions by the respective punch set of top and bottom punches, the At the end of pressing the powder,
Specially removes the pressing force acting on the pair of upper and lower punches evenly.
Sign.

After the pressure is released, the molded product is extracted from the die hole.
It is characterized by the following.

The stepped shaped article is a stepped shape having one end surface has a plurality of stepped portions, the other end surface is Ru flat shape der.

The filling of the powder into the die hole is performed by inserting the lower punches of the plurality of punch sets from below the die hole, and setting the upper end surface of each lower punch to a predetermined position corresponding to each step from the upper surface of the die. Is filled with the powder in the die hole, and then the upper punch is inserted into the die hole filled with the powder, and the filled powder is moved up and down by the upper and lower punches of each punch set. attached form side, Ru are moved relative to the lower punch side is a flat shape.

Activate the cushion cylinder simultaneously with pressure release
Of each punch group by the pressure of the cushion cylinder.
The molded product is sandwiched between the upper and lower punches, and the upper ram rises.
Also regulates sudden release of pressure by the force of the cushion cylinder
It is characterized by doing.

A die having a die hole for powder filling, a pair of upper and lower punch sets for compressing the powder filled in the die hole, and corresponding to each step size of a molded product in the die hole. Filling depth setting means for positioning the lower punch in the die hole so as to set the powder filling depth to a predetermined size, and inserting the upper punch into the die hole to move the filled powder up and down of each punch set. Transfer means for relatively moving the upper punch side by the punch so that the upper punch side becomes a stepped shape side; stopper means for holding the upper end surface of the lower punch of each punch set after transfer at a predetermined position and receiving a pressing force; Pressing means for moving the upper punch so that the density of each powder part compressed by the set is always the same during compression and pressing each powder part, and extraction means for extracting a molded product from the die hole,
At the end of pressurization, a load acting on each upper and lower punch of each punch set
Pressure release means for releasing pressure evenly.
Sign.

The upper punch unit of a plurality of punch sets is
Connected to the ram via a cushion cylinder
It is characterized by.

The lower punch side of the plurality of punch sets is moved by the transfer means so that the lower punch side becomes the flat shape side, and the upper end face of the lower punch is positioned and held at the same plane position by the stopper means.

[0022]

According to the present invention, since the compression density of each powder portion is constantly compressed during compression by the upper and lower punches of the punch set, there is no powder movement between the powder portions during molding. There are no cracks in the molded product.
At the end of pressurizing the powder,
The applied pressure is evenly released, and the molded product is
Since it is extracted from the hole, the boundary between the steps at the time of extraction
There is no risk of cracks occurring in the part.

In addition, a step is formed at the upper end side of the molded product by performing transfer after filling the powder, and the lower punch at the lower end is fixed at a predetermined position at the time of pressurizing. As in the case where a step is formed on the lower punch side, a plurality of lower punches can be directly extracted without having to release a stopper in order to position the plurality of lower punches at a predetermined position at the time of extraction.

In particular, if the lower end surface of the molded product is made flat,
Transport can be performed stably and smoothly. Although particularly effective in the case of a step-shaped molded product having a convex shape, damage to a concave portion can be prevented even in the case of a step-shaped molded product having a concave shape.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

FIG. 3 shows an example of a stepped product formed by the powder molding method of the present invention. The molded article 1 is used as a computer part and has a very thin square thin plate shape, one end surface of which is a flat surface 2 and the other end surface of which is a stepped surface 3 having a stepped shape. The stepped surface 3 is composed of a first step portion 4 at a peripheral portion and a second step portion 5 at a central portion which is one step higher than the first step portion 4. The planar shape of the second step portion 5 is a square shape smaller in diameter than the first step portion 4 and is arranged concentrically with the first step portion 4, and the second step portion 5 surrounds the periphery of the first step portion 4. It is configured as follows.

As shown in FIG. 4, the upper and lower punches for forming the molded article 1 are formed of a pair of upper and lower punches. That is, an upper first punch 6U and a lower first punch 6L as a first punch set 6 for forming the first step 4 and an upper second punch 6 as a second punch set 7 for forming the second step 5 7U and a lower second punch 7L. In FIG. 4, the inner upper and lower second punches 7U and 7L are projected so as to facilitate understanding of the structure.

The upper and lower first punches 6U and 6L are coaxially arranged in the same shape, and are formed in a hollow square cylindrical shape having the same cross-sectional shape as the first step portion 4 of the molded product 1. The upper and lower second punches 7U and 7L are also coaxially arranged in the same shape, and are formed in a quadrangular prism shape having the same cross-sectional shape as the second step portion 5 of the molded product 1. These upper and lower second punches 7U and 7L correspond to upper and lower first punches 6U and 6L, respectively.
The inner circumference is slidably fitted in the axial direction.

FIG. 5 shows a basic configuration example of a tool set portion of a powder molding press to which the present invention is applied.
The configuration of the upper first and second punches 6U and 7U and the lower first and second punches 6L and 7L is the same as the configuration shown in FIG.

The tool set is roughly divided into an upper punch unit 10 connected to the upper ram 9 of the press body 8,
And a lower punch unit 11 fixed to the press body 8. The drive of the upper ram 9 employs various drive mechanisms such as a mechanical pressurizing mechanism such as a crank mechanism and a toggle mechanism, a pressurizing mechanism using hydraulic pressure such as hydraulic pressure and air pressure, and an electric ball screw mechanism. Is also good.

The upper punch unit 10 includes an upper punch plate 12, a pressurizing cylinder 13 such as a hydraulic cylinder attached to the upper punch plate 12, and a pressurizing cylinder 13
And the upper and lower punches 6U and 7U.

The pressurizing cylinder 13 is fitted to a cylindrical cylinder core portion 14 whose upper end is fixed to the lower surface of the upper punch plate 12 and is slidable in the axial direction around the outer periphery of the cylinder core portion 14. Annular movable cylinder part 15
And is composed of An annular recess 16 is formed on the inner peripheral surface of the movable cylinder portion 15, while an annular piston portion 17 projecting into the annular recess 16 is provided on the outer periphery of the cylinder core portion 14. The outer periphery of the annular piston portion 17 is slidably and closely contacted with the inner peripheral wall of the cylindrical annular recess 16 in an oil-tight manner, and divides the annular recess 16 into two upper and lower chambers 18 and 19.

In this embodiment, the cylinder core 1
The upper second punch 7U is fixed to the lower end surface of the movable cylinder portion 15, while the upper first punch 6U is fixed to the lower end surface of the movable cylinder portion 15. Therefore, the upper second punch 7U moves integrally with the upper ram 9, and the upper first punch 6U moves with the upper ram 9, while the movement of the pressurizing cylinder 13 is superimposed on the upper second punch 7U. Move relative.

The upper punch plate 12 is connected to the upper ram 9. In this embodiment, the upper ram 9 is provided with a cushion cylinder 20, and the upper punch plate 12 is connected to the upper ram 9 via the cushion cylinder 20. It is connected.

The cushion cylinder 20 has a recess 21 formed in the lower end surface of the upper ram 9 and the opening of the recess 21 is
2 to form a hollow cylinder chamber 23, into which a piston 24 is inserted so as to be reciprocally movable in the axial direction and cylinderd, and a piston rod 25 is inserted through a rod hole 26 of the lid 22. The upper punch plate 1 is protruded downward and the rod protruding end is
2 are connected.

A guide pin 28 extending in the axial direction is attached to the joint block body 27.
Slidably inserted into a pin hole 29 provided in parallel with
Guides axial movement.

The upper punch unit 10 is axially movably supported by a die plate 31 of the lower punch unit 11 via a guide rod 10a having an upper end fixed to the upper punch plate 12. The lower end of the guide rod 10a is slidably inserted into the bush 10b to which the die plate 31 is fixed.

In order to prevent the pressurizing cylinder 13 from rotating, a bracket 13a for preventing rotation is provided on the movable cylinder portion 15 of the pressurizing cylinder 13, and the bracket 13a guides the upper punch unit 10. The guide rod 10a is slidably inserted into the guide rod 10a.

The lower punch unit 11 is provided with a die plate 31 on which a die 30 is fixed, a movable punch plate 32 provided below the die plate 31 and supporting the lower first punch 6L, and provided below the movable punch plate 32. Fixed plate 33 supporting the lower second punch 7L, and a die plate 31 provided further below the fixed plate 33.
And a lowering plate 34 that supports the The lowering plate 34 and the die plate 31 are connected via a plurality of fixed rods 35, and the fixed rod 35 connects the fixed plate 33 and the movable punch plate 32 provided between the lowering plate 34 and the die plate 31. It penetrates and guides the movement of the movable punch plate 32 in the axial direction.

The lower first punch 6L is fixed to the lower first punch plate 32 via a hollow lower first punch holder 36. On the other hand, the lower second punch 7L is fixed to the fixing plate 33 via the lower second punch holder 37. The lower second punch 7L is inserted into the lower first punch 6L through the hollow lower first punch holder 36, and the lower second punch holder 37 is inserted through a through hole 38 provided in the movable punch plate 32. The lower second punch holder 37 is a solid pillar member, the lower end of which is fixed to the fixing plate 33.

The fixed plate 33 is provided with a plurality of stoppers 39 for restricting the movable punch plate 32 from moving downward.

A punch support cylinder 40 such as an air cylinder for holding the movable punch plate 32 and positioning the lower first punch 7L in a free state is provided between the movable punch plate 32 and the fixed plate 33. Is provided. The punch support cylinder 40 is provided with the die hole 3
Positioning of the lower first and second punches 6L and 7L in the die hole 30 so as to set the powder filling depth corresponding to each step of the molded product within 0, and constitutes a filling depth setting means. I do.

The punch supporting cylinder 40 comprises a hollow cylinder tube 41, a piston portion 42 slidably inserted into the cylinder tube 41, and a rod 43 provided integrally with the piston portion 42. Have been. The cylinder tube 41 is fixed to the movable punch plate 32 via a bracket 44 projecting to the side of the movable punch plate 32. Piston rod 4
A screw portion 45 is provided at the lower end of the screw 3, and the screw portion 45 is fixed to a position adjusting mechanism in a gear box 46 provided on the fixed plate 33 as shown in FIG.

FIG. 6A shows a position adjusting mechanism inside the gear box 46.

That is, a worm wheel 46a fixed to the lower end of each piston 43 and a worm 46b meshing with the worm wheel 46a are provided.
The rotation of the worm 46b is converted into the vertical movement of the piston rod 43. In addition, between the worm shafts 46c are driven synchronously via a transmission mechanism 46D such as a chain and a sprocket, a timing belt and a pulley. In the illustrated example, the shaft end 46e of one worm shaft 46c is shown.
Is rotated and driven by a handle or the like. In this way, the piston rod 43 is moved up and down by rotating the worm wheel 46a, and the position of the piston portion 42 provided integrally with the piston rod 43 is moved up and down.

Cylinder upper chamber 4 of punch support cylinder 40
7, the cylinder tube 4
1 is pushed upward with respect to the piston portion 42, and the piston portion 42 is positioned at a position where the piston portion 42 contacts the lower end wall 41 a of the cylinder tube 41. That is, in the free state, the piston portion 42 comes into contact with the cylinder tube lower end wall 41a and stops by the fluid pressure such as the air pressure, and the lower first punch 6L is positioned at this position.

Therefore, the position of the lower first punch 6L can be adjusted by adjusting the position of the piston portion 42. There are a pair of punch support cylinders 40 on the left and right, and the rotation of the adjustment shaft 48 causes the left and right punch support cylinders 40 and 40 to move up and down in conjunction.

On the other hand, the punch supporting cylinders 40, 40
A transfer cylinder 49 as a transfer means is provided on the upper ram 9 side.

The transfer cylinder 49 is for transferring the powder 50 filled in the die hole 30a, and is disposed coaxially with the punch support cylinder 40 above the punch support cylinder 40 described above. The transfer cylinder 49 is attached downward on the left and right sides of the upper punch unit 10 via a plate 51 fixed to the upper ram 9, and has a cylinder tube 52 whose upper end is fixed to the plate 51, A piston 53 slidably inserted into the tube 52, a piston rod 54 connected to the piston 53 and having a lower end protruding downward from a lower end wall 52a of the cylinder tube 52;
And is composed of A threaded portion 55 is provided on the outer periphery of the lower end of the piston rod 54, and the upper end wall 41 of the cylinder tube of the punch support cylinder 40 below the threaded portion 55.
A pressing block 56 that can be brought into contact with the annular convex portion 41c provided at b is screwed.

The piston rod 54 projects to a lower limit position by a fluid pressure in a free state, and contracts upward when a predetermined pressure is applied.

On the other hand, the upper punch plate 12 of the upper punch unit 10 and the die plate 31 of the lower punch unit 11
Between them, a first linear sensor 58 for detecting the amount of powder pressing by the upper and lower second punches 7U and 7L is provided. The first linear sensor 58 has a lower end fixed to the die plate 31 and is erected vertically upward along the axial direction. A sensor pressing member 59 extending downward is provided on the lower surface of the upper punch plate 12, and is operated by the sensor pressing member 59.

The first linear sensor 58 and the sensor pressing member 59 contact each other at the pressure start position, and
The amount of powder pressurization by U, 7L is detected. In this embodiment, the pressure start position is the transfer completion position,
This is a position where the lower end of the punch 7U reaches the same plane as the upper surface of the die 30. An adjusting screw 60 for adjusting the vertical position is provided at the lower end of the sensor pressing member 59, and the first linear sensor 58
The operation start position of can be adjusted.

From this position, the amount of pressurization by the upper and lower second punches 7U and 7L, in this embodiment the lower second punch 7L is fixed, so the amount of downward movement of the upper second punch 7U is the amount of pressurization. The pressing start position is not necessarily the die hole 30a than the upper surface of the die 30.
It may be a position that has entered inside.

A pulse is generated from the first linear sensor 58 in accordance with the amount of pressurization by the upper second punch 7U, and the number of pulses is multiplied by a predetermined coefficient to obtain upper and lower first punches 6U and 6L.
In this embodiment, since the lower die 1 punch 6L is fixed, the moving speed of the upper die 1 punch 6U is determined, and the pressure cylinder 13 is controlled.

The upper punch unit 10 has a second linear sensor 62 for detecting the position of the upper first punch 6U.
Is provided. The second linear sensor detects the position of the upper first punch 6U with respect to the upper punch plate 12, and is provided on the lower surface of the second upper punch plate 12 so as to protrude downward in the axial direction. On the other hand,
A detection plate 63 protrudes laterally from the annular movable cylinder portion 15 of the pressurizing cylinder 13 for driving the punch 6U, and the detection plate 63 is connected to the second linear sensor 62.
To come into contact with the detection end.

FIG. 7A is a block diagram showing a control configuration of the pressurizing cylinder 13. As shown in FIG.

That is, a hydraulic control circuit provided with control means such as an electromagnetic valve for controlling the flow rate and the like of the pressurizing cylinder 13, a pressure supply unit 301 for supplying a hydraulic pressure such as a hydraulic pressure to the hydraulic control circuit 300, And a controller 302 for sending a control signal to the circuit 300.

The controller 302 receives information on the amount of pressurization of the upper second punch 7U from the first linear sensor 58 and position information on the upper first punch 6U from the second linear sensor 62.

Next, the molding process will be described with reference to FIGS. 1, 2, 5 and 7.

The molding step is roughly as follows.
0, a step of transferring the filled powder 50, a step of depressurizing after pressurizing, and a step of extracting the molded article 1 after depressurizing (FIG. 1).
reference).

In the powder filling step, a hollow feeder 64 having an open lower end is used. The lower end edge of the feeder 64 holding the powder 50 is brought into contact with the upper surface of the die 30, and the lower end edge of the feeder 64 is slid to open the feeder 64 opening. The die hole 30
a, and the powder 50 is placed in the die hole 30a by its own weight.
And filled in the die hole 30a. Then, the upper surface of the powder 50 filled in the die hole 30a coincides with the upper surface position of the die 30 by sliding the powder 50 filled in the die hole 30a at the upper surface position of the die 30 at the lower edge of the feeder 64 (FIG. 1 (a), (b) and FIG. 2 (a)).

The filling amount of the powder 50 is determined by the filling depth from the upper surface of the die 30 to the upper end surfaces of the lower first and lower second punches 6L and 7L, and corresponds to the upper end surface of the lower first punch 6L. The ratio between the filling depth of the powder portion to be filled and the filling depth of the second powder portion corresponding to the upper end face of the lower second punch 7L is the thickness of the first step portion 4 and the second step portion 5 of the molded product 1. The filling ratio is set to the same ratio, and the filling depth is set to about twice the thickness of the molded article 1.

In the transfer step, the upper punch unit 10 is moved downward integrally by driving the upper ram 9. At the start of the transfer, the lower end surface of the upper first punch 6U is located at the upper surface of the die 30, that is, at the upper end of the powder (see FIG. 1B). The lower end surface of the upper first punch 6U is set to have a relative positional relationship such that the lower end surface projects below the lower end surface of the upper second punch 7U by a predetermined distance.

The amount of protrusion is set to a dimension equal to the relative distance from the upper end surface of the lower first punch 6L to the upper end surface of the lower second punch 7L, and is symmetrical with the lower first and second punches 6L, 7L. This is a positional relationship (see FIG. 1B). The protrusion amount can be measured by detecting the position of the upper first punch 6U with respect to the upper second punch 7U by the second linear sensor 62, and the position can be adjusted by the pressing cylinder 13.

At the start of the transfer, the left and right transfer cylinders 49, 49 are also moved downward with the movement of the upper punch unit 10, and the pressing member 5 at the lower end thereof is moved.
The lower end surfaces of the cylinders 56 are in contact with the annular convex portion 41c at the upper end of the cylinder tube 41 of the punch supporting cylinders 40,40.

Then, as the upper ram 9 moves downward, the upper first punch 6U enters the die hole 30a. On the other hand, as the upper ram 9 moves downward, the lower first punch 6U is synchronized with the upper first punch 6U by the pressing member 56 at the lower end of the transfer cylinder 49 via the annular projection 41c, the cylinder tube 41 and the movable punch plate 32. When the upper end surface of the lower first punch 6U reaches the same level as the upper end surface of the lower second punch 7U.
2 stops against the stoppers 39, 39 and stops. This position is the transfer end position, and the lower end surface of the upper second punch 7U has reached the upper surface position of the die 30. Accordingly, the powder portion sandwiched by the first punch set 6 is slid basically without any compression and basically at the density at the time of filling. In this way, the upper surface of the lower first punch 6L and the upper surface of the lower second punch 6L are positioned at the same position to form one continuous plane corresponding to the flat surface 2 of the molded article 1 (see FIG. c)).

The transfer cylinder 49 is set to have a stronger force than the punch support cylinder 40.

When the transfer is completed, the first linear sensor 58 comes into contact with the sensor pressing member 59, and the condition signal is used as a condition signal for starting pressurization. This pressurizing start position is adjusted by adjusting screw 60
Can be adjusted by

In the pressurizing step, the pressurizing cylinder 13 for driving the upper second punch 7U is controlled based on the signal from the first linear sensor 58. The control of the pressurizing cylinder 13 is corrected based on the position information.

In the pressing step, the upper and lower first punches 6U, 6U
L and the corresponding powder portions are simultaneously compressed in the axial direction by the upper and lower second punches 7U and 7L. At this time, compression is performed so that the density of each powder portion is always the same during the compression (see FIG. 1D).

For this purpose, in this embodiment, the pressing speed v1 of the upper and lower first punches 6U and 6L and the upper and lower second punch 7
The ratio of the pressing speed v2 by U and 7L is controlled to be the same as the ratio α of the axial dimension of the first step 4 and the second step 5.

In this embodiment, the lower first and second punches 6L, 7L
Since L is fixed together, the upper first and second punches 6
Only the speeds on the U and 7U sides need to be considered.
Since the punch 7U is driven by the upper ram 9, the pressurizing cylinder 13 is controlled to move the upper first punch 6U in accordance with the driving of the upper ram 9. In this pressurizing step, the transfer cylinders 49, 49 are pressed by the annular convex portions 41c at the upper ends of the punch support cylinders 40, 40 and contract.

Assuming that the lowering speed of the upper ram 9 is v, the lowering speed v2 of the upper second punch 7U corresponding to the compression speed of the upper and lower second punches 7U and 7L is equal to the lowering speed v of the upper ram.

On the other hand, the upper first punch 6U is moved downward together with the upper second punch 7U by the upper ram 9, and when compressing the powder, it is moved upward with respect to the upper second punch 7U.

The speed v1 of the first punch 6U is a speed obtained by subtracting the speed v of the upper ram 9 by the rising speed vs. by the pressurizing cylinder 13, and is given by (v1 = v-vs). Since the ratio between v1 and v2 may be set to be the ratio α of the axial dimension of the first and second steps 4 and 5 of the molded product 1, the rising speed vs of the pressing cylinder 13 is v ( 1-α).

In this manner, the density of the powder portion compressed by the first upper and lower punches 6U and 6L and the density of the powder portion compressed by the second upper and lower punches 7U and 7L at any moment during the pressurizing step. The density is always the same and a uniform stepped product can be obtained.

To explain with reference to the control block diagram of FIG. 7A, the pressurization amount information detected by the first linear sensor 58 is read into the controller 302 by a pulse signal or the like, and the controller 302 performs the above calculation.
The data of the molded product, the calculation software, and the like necessary for this calculation are input to the controller 302 in advance and stored.

Then, the controller 302 calculates the pressurizing speed v1 of the upper second punch 7U based on the pressurizing amount information and the clock pulse inside the controller, and further multiplies it by a coefficient (1−α). Rise speed vs
Is calculated, and a control signal is sent to the hydraulic circuit 300 so that the first
The punch 6U is controlled to move down at the speed v2.

Further, the position of the upper first punch 6U is detected by the second linear sensor 62, and the position information can be fed back so that very precise control can be performed.

As a pressing method, in the illustrated example, the lower first and second punches 6L and 7L are fixed and the upper first and second punches 6L and 7L are fixed.
U and 7U are pressed in a one-sided manner, but may be double-pressed.
U, 7U, die 30 and lower first and second punches 6L,
7L is lowered and the speed difference between the upper and lower first punches 6U and 6L and between the upper and lower second punches 7U and 7L.
A withdrawal method of compressing the powder portion between L may be employed, or various pressure methods may be employed.

When the pressurization is completed, the operation of the pressurizing cylinder 13 is stopped at the bottom dead center of the upper ram 9 to release the pressure.

Depressurizing means releasing the pressing force applied to each of the steps 4 and 5 so that the steps 4 and 5 of the molded article are elastically restored evenly at the end of pressurization. In the process of raising the upper first and second punches 6U and 7U at the end of pressurization, the difference between the springback amounts of the first and second step portions 4 and 5 of the molded article 1 and the respective punches 6U and 6L; Due to the difference between the elastic strain amounts of 7U and 7L, the first and second step portions 4 and 5 do not uniformly return elastically. For example, the first step 4 is the upper first punch 6
When the pressure on the second step 5 is released while still being pressed by U, a crack is formed at the boundary between the first step 4 and the second step 5 due to the extension of the second step 5 due to elastic return. May occur.

In particular, in the case of an extremely thin molded article having a low strength as in this embodiment, cracks are likely to occur.

In consideration of the amount of elastic deformation of each punch and punch adapter and the amount of springback of each step of the molded product, the pressurizing cylinder 13 is moved up or down in accordance with the amount of rise of the upper ram 9. Let it. Thereby, the pressure is adjusted so that the pressure between the upper first and second punches 6U and 7U is evenly released (see FIG. 2 (d ')). And so on.

In this embodiment, the cushion cylinder 20 is actuated at the same time as the pressure is released, and the molded product 1 is sandwiched by the cushion cylinder 20. Even if the upper ram 9 rises, the upper first and second punches 6U, 6U 7U regulates that the molded article 1 is pressed with a predetermined force and the pressure is suddenly released.

The cushion cylinder 20 fills the cylinder lower chamber 23b with a fluid pressure until the pressurization is completed, and lifts the entire upper punch unit 10 upward. The pressure is released to fill the cylinder upper chamber 23a with the fluid pressure, and the entire upper punch unit 10 is pushed downward. However, the switching of the fluid pressure may be performed before the pressurization is completed.

Thereafter, the molded article 1 is extracted (FIG. 1).
(e)).

The molded product 1 is extracted by using the cushion cylinder 20 to lower the lower end of the upper second punch 7U.
The upper first punch 6 in contact with the upper end surface of the second step 5
The lower end surface of U is raised until it is at the same position as the lower end surface of upper second punch 7U.

Next, the upper second punch 7U and the lower first and second punches 7U
In a state where the molded product 1 is vertically sandwiched by the punches 6L and 7L, the lower ram is moved down to lower the die plate 31 via the pull-down plate and the fixed rod, and the die 30
By lowering the first and second punches 6L and 7L relative to each other, the molded article 1 is pushed out to the upper surface of the die 30 to perform the extraction, and at the same time, the upper second punch 7U is stopped and the upper first punch 7U is stopped. Raise 6U. Then, the cushion cylinder 20 is raised to complete a series of operations (FIG. 1).
(e)).

When the removal of the molded article is completed, the molded article 1
Is transported by sliding the upper surface of the die 30. This conveyance is pushed laterally by the advancing feeder 64 to fill the powder 50 of the next molding step, and at the same time, the powder 50 for the next molding is filled in the die hole 30a (FIG. 1 (a) )reference).

FIG. 6B shows a second embodiment of the present invention.

In the second embodiment, the connection between the above-mentioned first and second punches 6U and 7U and the pressurizing cylinder 13 is reversed.

That is, the cylinder part 151 to which the upper first punch 6U is fixed is fixed to the upper punch plate 12 and is moved integrally with the upper ram 9, and the cylinder core part 141 to which the upper second punch 7U is fixed is moved. Upper second punch 7 as movable
U is moved relative to the upper first punch 6U.

FIG. 7B is a control block diagram in the case of the second embodiment.

That is, in this example, the upper first punch 6U
Move integrally with the upper ram 9, the first linear sensor 58 detects the amount of movement of the upper first punch 6U. The operation start time of the first linear sensor 58 is the transfer end position, that is, the pressurization start position. When the upper second punch 7U reaches the upper surface of the die, the upper first punch 6U enters the die hole 31a by a predetermined amount. Position.

In this example, since the amount of pressurization of the upper second punch 7U is controlled based on the amount of pressurization of the upper first punch 6U, unlike the above embodiment, the upper first and second punches 6U, 7U Move down together. That is, the speed v1 of the upper first punch 6U is the same as the speed v of the upper ram 9, and the moving speed v2 of the upper second punch 7U is the speed v of the upper ram 9 and the pressing speed vs. The pressurizing speed vs. of the pressurizing cylinder is determined so that the ratio of (v + vs) to v1 is equal to the ratio α between the steps 4 and 5. That is, the pressure cylinder vs. is (1-1 / α)
v.

The other configuration is the same as that of the above-described embodiment, so that the same components are denoted by the same reference numerals and description thereof will be omitted.

FIGS. 8 and 9 show a third embodiment of the present invention.

As in the first embodiment, the molding step includes a step of filling the powder 50 into the die hole 30a, a step of transferring the filled powder 50, a step of depressurizing after the pressing is completed, and Extracting the molded product after the extraction.

The second embodiment is also a molded product in the form of a square thin plate having a flat surface 202 at one end surface, as in the first embodiment, but as shown in FIG. In the example, the projection surface has a convex step shape, whereas the concave step surface 203 has a concave step shape. That is, the stepped surface 203 includes a first step portion 204 at a peripheral portion and a second step portion 205 at a central portion one step lower than the first step portion 204. The planar shape of the second step portion 205 is a square shape having a smaller diameter than the first step portion 204, and is arranged concentrically with the first step portion 204. The second step portion 205 surrounds the periphery of the first step portion 204. It is configured as follows.

FIG. 9 shows a basic configuration example of a tool set portion of the powder molding press according to the second embodiment.

Since the basic configuration is exactly the same as that of the first embodiment shown in FIG. 5, the same components are denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described. And

The upper punch unit 210 differs from the first embodiment in that the length relationship between the upper first and second punches 206U and 207U is shorter than the upper first punch 206U is shorter than the upper second punch 207U. Exactly the same.

Regarding the lower punch unit 211, the first punch unit
In the embodiment, the lower first punch 6L is movable, and the lower second punch 7L is movable.
While L is fixed, in the second embodiment, the lower first
The difference is that the punch 206L is fixed and the lower second punch 207L is movable, and the other configurations are completely the same.

That is, in the second embodiment, the lower second punch 207L is supported by the movable punch plate 232 via the hollow lower second punch holder 237, and the lower first punch 206L is supported by the lower first punch holder 236. And is supported by the fixed plate 33 via the.

The lower first punch holder 236 is inserted into the center hole 232a of the movable punch plate 232, and the upper end thereof is inserted into the hollow lower second punch holder 237. 236 a Hole 237 provided in second lower punch holder 237 standing upright on upper end surface
and a plurality of rod portions 236b extending upward through a to support the lower first punch 206L.

In the second embodiment, in the transfer step, the lower second punch 207L is pushed down and the stopper 23 is pressed.
9 and the upper end position is fixed.
Match the upper end position of L.

[0108]

As described above, according to the present invention,
Since the compression density of each powder part is constantly compressed during compression by the upper and lower punches of the punch set, there is no powder movement between the powder parts during the molding, and cracks do not occur in the molded product. Also, at the end of pressurizing the powder,
Equally remove the pressing force acting on the upper and lower punches of each punch set.
The molded product is pulled out of the die hole after depressurizing
Causes cracks at the boundary between the steps during extraction
There is no fear.

Also, after the powder is filled, transfer is performed to form a step on the upper end side of the molded product, and the lower punch on the lower end is fixed on a flat surface. As in the case where a step portion is formed on the side, the upper end positions of the plurality of lower punches are positioned on the same surface at the time of extraction, so that the extraction can be performed without releasing the stopper.

Furthermore, the lower end surface of the molded article is a flat surface, so that it can be transported stably and smoothly. Although this is particularly effective in the case of a step-shaped molded product having a convex shape, damage to the concave portion can be prevented even in the case of a step-shaped molded product having a concave shape.

[Brief description of the drawings]

FIG. 1 is a process diagram showing a molding step of a powder molding method for a stepped molded product according to a first embodiment of the present invention.

2 (a) is a stroke diagram corresponding to the molding process of FIG. 1, and FIGS. 2 (d), 2 (d ') and 2 (e) show the completion of pressurization and depressurization in FIG. 2 (a). FIG. 4 is a schematic explanatory view of an upper punch unit at a withdrawal position.

3 (a) to 3 (d) show a stepped molded product molded by the molding method of the present invention, wherein FIG. 3 (a) is a plan view,
FIG. 1B is a side view, FIG. 1C is a sectional view, and FIG. 1D is a perspective view.

FIG. 4 is an explanatory diagram showing a configuration example of a pressure punch.

FIG. 5 is a schematic configuration diagram of a main part of a powder molding apparatus according to a first embodiment of the present invention.

6 (a) is a view showing a mechanism in a gear box portion of the apparatus of FIG. 5, and FIG. 6 (b) is a view of an apparatus configuration according to a second embodiment of the present invention, particularly, an upper punch and a pressurizing cylinder. It is a figure showing a connection part.

7 (a) is a block diagram showing the configuration of a pressurizing cylinder of the first embodiment of FIG. 5, and FIG. 7 (b) is a pressurizing cylinder of the second embodiment of FIG. 6 (b). FIG. 3 is a block diagram illustrating a control configuration.

FIG. 8 is a process diagram showing a molding step of a powder molding method for a stepped molded product according to a third embodiment of the present invention.

FIG. 9 is a schematic diagram of a main part of a powder molding apparatus according to a third embodiment of the present invention.

FIGS. 10A to 10C are cross-sectional views of each step of a conventional powder molding apparatus.

FIG. 11 is a process diagram of a conventional method of powder molding a stepped molded product.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Step-formed product 2 Flat surface 3 Stepped surface 4 1st step part 5 2nd step part 6, 7 1st, 2nd punch set 6U, 7U; 6L, 7L Upper 1st, 2nd; Lower 1st Second
Punch 8 Press body 9 Upper ram 13 Pressure cylinder 20 Cushion cylinder 30 Dice 31 Die plate 32 Movable plate 33 Fixed plate 34 Pull down plate 39 Stopper 40 Punch support cylinder (filling amount setting means) 49 Transfer cylinder (transfer means) 50 Powder 58 Upper second linear sensor 62 Upper first linear sensor 64 Feeder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B30B 11/04 B22F 3/02 B30B 11/00 B30B 11/02

Claims (3)

(57) [Claims] 1. A stepped molded product having a stepped shape having a plurality of steps at one end surface and a flat shape at the other end surface. A pair of upper and lower punches corresponding to each stepped portion of the molded product. Prepare a set of a plurality of punch sets, insert the lower punches of the plurality of punch sets from below the die hole, and set the upper end surface of each lower punch to a predetermined depth corresponding to each step from the upper surface of the die. Position and fill the powder into the die hole, then insert the upper punch into the die hole filled with the powder, the filled powder by the upper and lower punch of each punch set,
In the powder molding method of a step-formed product, the upper punch side is relatively moved so that the stepped shape side and the lower punch side are flattened, and then the corresponding powder portion is compressed by each punch set to form a stepped shape. The powder parts are simultaneously pressed by the upper and lower punches of each punch set so that the density of each powder part pressed by each punch set is always the same. A powder molding method for a stepped molded product, wherein pressure applied to upper and lower punches is evenly removed, and the molded product is removed from a die hole after depressurization. 2. The cushion cylinder is actuated simultaneously with depressurization, and the molded product is sandwiched between the upper and lower punches of each punch set by the pressure of the cushion cylinder. Even if the upper ram rises, the pressure is suddenly increased by the force of the cushion cylinder. 2. The method of molding a stepped molded product according to claim 1, wherein the molding is restricted from falling off. 3. A die having a die hole for filling powder, a pair of upper and lower pairs of punches for compressing the powder filled in the die hole, each step size of a molded product in the die hole. Filling depth setting means for positioning the lower punch in the die hole so as to set the powder filling depth to a predetermined size corresponding to the above, and inserting the upper punch into the die hole to fill the filled powder with each punch set. Transfer means for relatively moving the upper punch side by the upper and lower punches so that the upper punch side becomes the stepped shape side; stopper means for receiving the pressing force while holding the upper end surface of the lower punch of each punch set after transfer at a predetermined position; Pressurizing means for moving the upper punch to pressurize each powder portion so that the density of each powder portion compressed by each punch set is always the same during compression, and extracting means for extracting a molded product from the die hole, At the end of pressurization Pressure releasing means for uniformly releasing the pressing force acting on each of the upper and lower punches of each punch set, wherein the upper punch unit of the plurality of punch sets is connected to the upper ram via a cushion cylinder. Characteristic powder molding equipment for stepped molded products.