JP2535135Y2 - Compacting equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compacting apparatus mainly used in powder metallurgy.

[0002]

2. Description of the Related Art In recent years, mechanical parts such as gears have also been formed by powder sintering, and a compacting apparatus used for such production has been disclosed in, for example, Japanese Utility Model Laid-Open No. 60-15636. I have. The basic configuration of the device will be described with reference to FIGS. 1 to 4 which are explanatory diagrams of the present invention. FIG. 1 shows a structure of a die set incorporated in, for example, a mechanical press device. In this die set, a die plate 3 is provided on the upper side of a base plate 2 in a fixedly mounted state, and a lower side is provided. Yoke plate 4
Are provided respectively. The die plate 3 and the yoke plate 4 are mutually connected by columns 5.5 so that they can move up and down integrally.

A die 6 is mounted at the center of the die plate 3, and an upper end of a core rod 8 extending through the base plate 2 from below is inserted into a molding hole 7 of the die 6. The lower end of this core rod 8
It is supported by an air cylinder 11 mounted on the yoke plate 4. The lower punch 15 that covers the compacting space between the inner peripheral surface of the die 6 and the outer peripheral surface of the core rod 8 from below is fixed at the lower end to the base plate 2.

[0004] The powder compacting space is filled with metal powder 30 and, as shown in FIG. 2, the upper punch 31 is lowered to perform compacting. Thereafter, the upper punch 31 is withdrawn upward, and the die plate 3 and the yoke plate 4 are lowered as shown in FIG.
Is taken out. At the time of this removal, the green compact 30
a large clamping pressure is generated on both the inner and outer surfaces of a,
In this state, when the core rod 8 is lowered simultaneously with the die 6, a large frictional force is generated on both the inner and outer surfaces of the green compact 30a. As a result, the green compact 30a is cracked and cracked.

Accordingly, while the frictional force due to the force in the diameter reducing direction (hereinafter, this force is referred to as a biting force) by the powder compact 30a on the core rod 8 is large, the core rod 8
Operates integrally with the green compact 30a to cause a downward movement only on the die 6 side. That is,
A downward pressing force acts on the core rod 8 in accordance with the pressure of the air supplied to the air cylinder 11, and the pressing force is set to be smaller than the frictional force due to the biting force. Has been adjusted.

When the upper end side of the green compact 30a reaches a position slightly protruding from the upper surface of the die 6 as shown in FIG. 3, the restrained state of the green compact 30a on the outer peripheral side is relaxed. Therefore, the internal stress of the green compact 30a is reduced, whereby the biting force on the core rod 8 on the inner peripheral side is also reduced. The frictional force due to the biting force at this stage becomes smaller than the pressing force in the air cylinder 11, and the core rod 8 descends, that is, the extraction operation occurs. As a result, as the die plate 3 further descends, the core rod 8 also descends to its lower limit position, and as shown in FIG.
a is entirely extruded from the die 6 and taken out of the apparatus.

As described above, the core rod 8 lowers the die plate 3 and the yoke plate 4 so that the green compact 30
a at the initial stage of taking out the powder compact 3
The yoke plate 4 is supported via an air cylinder 11 so as to be able to move integrally with 0a. Conventionally, as described above, the air cylinder supporting the core rod as described above is provided with a pressing force on the core rod 8 at a point in time when the core rod biting force due to the green compact is reduced in the removal process, That is, air is supplied in such a manner that a supply pressure at which the extraction force is reversed is obtained.

[0008]

However, even when air is supplied to the air cylinder at the supply pressure determined as described above, the force of biting the core rod by the green compact does not affect the metal powder. Since it fluctuates due to variations in the filling amount and variations in the degree of lubrication on the peripheral surface of the green compact, for example, the air supply pressure often becomes too high. At this stage, cracks occur in the green compact as described above without causing the core rod to move integrally with the green compact. on the other hand,
If the air supply pressure is too low, the core rod will not be properly pulled out.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to eliminate the occurrence of defects such as cracks in a green compact when removing the green compact from a die. Another object of the present invention is to provide a compacting apparatus capable of stably causing a core rod withdrawing operation.

[0010]

SUMMARY OF THE INVENTION Therefore, a compacting apparatus according to a first aspect of the present invention comprises a base plate, a die plate movable relative to the base plate, and a yoke plate movable integrally with the die plate. A cylindrical lower punch that covers the compacting space in the forming hole of the die mounted on the die plate from the base plate side is fixed to the base plate, while the tip side penetrates the lower punch and the tip side is formed as described above. The base end side of the core rod located in the hole is connected to a piston in an air cylinder attached to the yoke plate, and the yoke plate is moved to a position closer to the yoke plate than the piston to apply a pressing force toward the yoke plate. An air supply line for supplying compressed air to the cylinder chamber on the side opposite to A powder compacting device in which a powder compact in a powder compacting space is extruded from a molding hole by a lower punch and is taken out by relatively moving a plate in a direction toward the base plate side, and is connected to the air supply line. A non-return valve that allows air flow in the direction toward the air cylinder and shuts off the flow in the opposite direction is interposed.

According to a second aspect of the present invention, there is provided a powder compacting apparatus as set forth in the first aspect, wherein an auxiliary volume is reduced between the base plate and the die plate when the two plates approach each other. An auxiliary cylinder containing a cylinder chamber is provided, and in the auxiliary cylinder chamber,
A branch line branched from the air cylinder side of the check valve in the air supply line is connected.

[0012]

In the compacting apparatus according to the first aspect,
Even if the air supply pressure to the air cylinder is set to ensure that the core rod and the compacted body integrally operate at the initial stage of taking out the compacted body, the check valve is provided in the air supply line. Is interposed,
With the integral operation of the core rod with the compact, the volume in the cylinder chamber of the air cylinder decreases and the pressure increases.

Therefore, when the biting force against the core rod is reduced during the removal of the green compact, the air pressure in the cylinder chamber is increased as described above, so that the core rod has a larger pressure than before. Since the removal force acts, the removal operation of the core rod can be more reliably performed without causing defects such as cracks in the green compact.

Further, in the powder compacting apparatus according to the second aspect, the operation state of a higher extraction force can be obtained during the operation of extracting the core rod. In other words, on the air cylinder side, the operation in the core rod extraction direction occurs, so that the inner volume of the cylinder chamber changes in the increasing direction. Therefore, in the case of this air cylinder alone, the extraction is performed along with the core rod extraction operation. The force gradually decreases to one that responds to the initial air supply pressure.

However, in the above, at this time, on the auxiliary cylinder side, while the approaching operation between the base plate and the die plate continues, the state in which the internal volume of the auxiliary cylinder chamber changes in the decreasing direction continues. Therefore, the rate of increase in the total volume of both cylinder chambers, that is, the degree of decrease in the core rod withdrawal force is smaller, and a higher withdrawal force is maintained. As a result, the extraction operation of the core rod can be more reliably caused.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

A die set shown in FIG. 1 is formed in the compacting apparatus of the present embodiment. The die set includes a base plate 2 fixed to a bed 1 of, for example, a mechanical press (not shown). Is provided. A die plate 3 is provided above the base plate 2, and a yoke plate 4 is provided below the base plate 2 in parallel with the base plate 2. The die plate 3 and the yoke plate 4 are connected to each other by columns 5.5 penetrating the base plate 2 on the left and right sides, so that the die plate 3 and the yoke plate 4 move up and down integrally. Has become.

A ring-shaped die 6 is mounted at the center of the die plate 3. A core rod 8 is inserted from below into the center through hole of the die 6, that is, into the forming hole 7 at a position concentric with the hole. On the other hand, an air cylinder 11 is provided at the center of the upper surface of the yoke plate 4.
The lower end of the core rod 8 is connected via a rod connecting portion 14 to the upper end of a piston rod 13 extending upward from a piston 12 slidable up and down in the cylinder chamber. That is, the core rod 8 extends downward through the center of the base plate 2, and the lower end thereof is supported by an air cylinder 11 provided on the yoke plate 4. , Air), the core rod 8 is held in a state where it is pressed to its lower limit position by air pressure.

The upper end of the core rod 8 is formed in a cylindrical shape, and the outer diameter of the upper end cylindrical portion is formed smaller than the inner diameter of the forming hole 7 in the die 6. The space between both surfaces created by this is a compacting space. A lower punch 15 covering the bottom of the compacting space is provided coaxially with the core rod 8 with its lower end fixed to the base plate 2 by a lower punch holder 16. The lower punch 15 has an outer peripheral surface shape that fits into the forming hole 7 and is formed in a cylindrical shape having an axial hole having an inner diameter dimension into which the upper end cylindrical portion of the core rod 8 fits. And the core rod 8 is in an assembled state penetrating from below.

The air is supplied to the air cylinder 11 as described above. For this purpose, the air supply line 21 allows the air to flow toward the air cylinder 11 while the air flows in the opposite direction. Check valve 22 for shutting off
Is interposed. In addition, the air supply line 21 has a safety valve, which is disposed closer to the air cylinder 11 than the check valve 22 so as to release air to the outside when the pressure in the cylinder chamber of the air cylinder 11 exceeds an allowable pressure. A relief valve 23 is further provided.

On the other hand, an auxiliary cylinder 24 is further mounted on the upper end of the base plate 2. A piston rod 26 extending upward from a piston 25 slidable in the auxiliary cylinder chamber in the auxiliary cylinder 24 is fixed to the lower surface of the die plate 3 at its upper end. The auxiliary cylinder 24 is provided with an air supply port 27 on the bottom side. The air supply port 27 is connected to a branch line 28 branched from the air supply line 21 on the air cylinder 11 side of the relief valve 23. It is connected. Therefore, the air supplied to the air supply line 21 is supplied to each of the cylinder chambers of the air cylinder 11 and the auxiliary cylinder 24, and both cylinder chambers communicate with each other through the branch line 28 and the air supply line 21. Therefore, both cylinder chambers are maintained at the same pressure.

The operation of the apparatus having the above-described structure during compacting will be described below.

First, in the initial state, the die plate 3 and the yoke plate 4 are held at the upper limit position shown in FIG. 1 by upper limit position urging means such as an air cylinder (not shown). At this position, the metal powder 30 is filled in the compacting space in the forming hole 7 of the die 6. In this state, air at a predetermined pressure is supplied to the cylinder chambers of the air cylinder 11 and the auxiliary cylinder 24 through the air supply line 21.

When the operation of the press device is started and the upper ram (not shown) starts to descend, the upper punch 31 attached to the upper ram via an air cylinder (not shown) is moved. As shown in FIG. 2, the metal powder is inserted into this space so as to cover the upper surface side of the powder compacting space, and the subsequent lowering operation causes the powder compact for the metal powder to pass between the upper punch 31 and the lower punch 15. As a result, a ring-shaped green compact 30a is formed. At this time, as shown by an arrow A in the figure, the die plate 3 has a so-called floating die structure in which some lowering operation occurs. That is, when the frictional force between the green compact 30a and the inner peripheral surface of the die 6 increases with the green compaction, the die plate 3 also descends due to the frictional force.
A green compact 30a having a more uniform density is formed.

When the upper punch 31 reaches the lower limit position and the compacting is completed, the upper punch 31 is pulled out upward.
Then, the operation is directly switched to an operation in which the die plate 3 is further caused to descend by the lowering of the upper ram. As a result, the operation shifts to the operation of removing the green compact 30a. That is, as shown by arrow B in FIG.
When the lowering operation is further performed on the die plate 3, the green compact 30 a on the lower punch 15 in the fixed state becomes
It rises relatively to the die plate 3 and is pushed upward from inside the forming hole 7 in the die 6.

By the way, in this way, the green compact 30
When taking out a, it is also necessary to pull out the core rod 8 that penetrates the center of the green compact 30a from below from the green compact 30a. However, in the above-described apparatus, as shown in FIG. 3, until the upper end side of the green compact 30a reaches a position protruding slightly from the upper surface of the die 6, the core rod 8 is not in contact with the green compact 30a. An integral operation, that is, a stationary state is maintained. In other words, in the removal process, the green compact 30a has a large internal stress due to compression in the green compacting process. On the other hand, a large force is acting in the radially increasing direction, and a large force is also acting on the core rod 8 in the radially decreasing direction from the powder compact 30a. In this state, when the core rod 8 is simultaneously lowered together with the die 6, the green compact 30a
A large frictional force is generated on both the inner and outer surfaces of the powder compact, and as a result, a crack is generated in the green compact 30a, and the crack is easily generated.

Therefore, in the above description, the green compact 30a
While the frictional force caused by the force in the diameter reducing direction on the core rod 8 (hereinafter, this force is referred to as the biting force) is large, the core rod 8 operates integrally with the powder compact 30a and the die 6 side Only the lowering operation is caused. That is, a downward pressing force (hereinafter, referred to as a core rod removing force) acts on the core rod 8 in accordance with the pressure of the air supplied to the air cylinder 11, but the entire powder compact 30a is a die. During the position within 6, the pressure for supplying air to the air cylinder 11 is set so that the core rod withdrawal force is smaller than the frictional force due to the biting force. Accordingly, the yoke plate 4 also descends integrally with the die plate 3, but the piston 12 relatively rises in the air cylinder 11 against the air pressure. Body 30a
And rise relatively.

When the upper end side of the green compact 30a reaches a position slightly protruding from the upper surface of the die 6 as described above, the restrained state on the outer peripheral side of the green compact 30a is relaxed. The internal stress of the green compact 30a is reduced, and the biting force on the core rod 8 on the inner peripheral side is also reduced.

After reaching this state, the lowering operation of the core rod 8 occurs. Until the lowering operation occurs, in the cylinder chamber of the air cylinder 11, since the piston 12 relatively rises as described above and the volume in the cylinder chamber decreases, the air supplied to the cylinder chamber is , Its pressure rises above the pressure at the time of supply. That is, the air supply line 21 is connected to the check valve 2 as described above.
2, the pressure in the cylinder chamber is
It rises almost in inverse proportion to the above volume change. Therefore,
As described above, the biting force of the core rod 8 by the green compact 30a is reduced, but the air in the cylinder chamber where the pressure is increased as described above causes the core rod 8 to be in a state of a large core rod removing force. Accordingly, the lowering operation of the core rod 8 is started.

Then, as shown in FIG. 4, when the die plate 3 is lowered to the position shown by the arrow C in the figure and the core rod 8 is also lowered to its lower limit position, the upper end surfaces of the die 6 and the core rod 8 are moved. Are located substantially flush with the upper end surface of the lower punch 15 and the powder compact 3
Oa is located entirely above the die plate 3. In this state, the green compact 30a is taken out of the apparatus, and a cycle of the molding process is completed. After that, the die plate 3 and the yoke plate 4 are raised to the initial position, and the process proceeds to the next molding cycle.

When the lowering operation is performed on the core rod 8, a maximum pressing force is required at the start of the operation, and once the lowering operation is performed, the green compact 30a is pressed.
Is changed from static frictional force to dynamic frictional force, and the unconstrained portion of the die 6 on the outer peripheral side of the powder compact 30a is widened as it descends. Since the applied force is reduced, the pressing force of the core rod 8 can be gradually reduced. Therefore, as the volume of the cylinder chamber in the air cylinder 11 increases as the core rod 8 descends, the pressure in the cylinder chamber gradually decreases to the air supply pressure from the air supply line 21. Also in this state, the stable extraction operation of the core rod 8 is maintained.

However, in the above embodiment, the provision of the above-mentioned auxiliary cylinder 24 further
Even during the operation of extracting the core rod 8, a larger core rod extracting force acts on the core rod 8. That is, since the die plate 3 moves down and the distance from the base plate 2 decreases, the volume in the cylinder chamber in the auxiliary cylinder 24 decreases.
Thereby, while the lowering operation is occurring in the core rod 8,
Although the volume of the cylinder chamber increases on the side of the air cylinder 11, the total volume increase of the cylinder chambers of the air cylinder 11 and the auxiliary cylinder 24, that is, the pressure drop decreases. As a result, a larger core rod removing force also acts during the lowering operation of the core rod 8, so that the extracting operation of the core rod 8 occurs more reliably.

As described above, the air cylinder 11
When the pressure change in the auxiliary cylinder 24 occurs with the progress of the molding cycle, and if this pressure exceeds the allowable set pressure due to some abnormality, the relief valve 23 operates to allow the pressure to fall within the allowable set pressure. It is maintained and safety is ensured.

As described above, in the above embodiment, the check valve 22 is interposed in the air supply line 21 and the auxiliary cylinder 24 is provided so that the core rod 8 can perform a stable extraction operation. Has become. That is, even when the air supply pressure to the air cylinder 11 is set so that the integral operation of the core rod 8 with the powder compact 30a is reliably generated in the initial stage of taking out the powder compact 30a, the air supply line Since the check valve 22 is interposed in the core 21, the core rod withdrawal force with respect to the core rod 8 increases during the operation at the initial stage of the removal. As a result, when the biting force decreases during the removal of the green compact 30a, the core rod 8 reliably switches to the removal operation, and the lowering operation by the auxiliary cylinder 24 increases the core rod removal force. Is to occur. Thereby, the green compact 30a without cracks and cracks can be stably produced without causing the extraction failure of the core rod 8.

In the above-described embodiment, the green compact 30a is described as having only a ring shape. However, for example, an arbitrary peripheral surface such as a gear having a tooth profile on the outer peripheral surface and a keyway on the inner peripheral surface is described. It can be configured to have a shape. Further, an apparatus having a structure in which the lower punch 15 is divided into a plurality of parts, in order to form a green compact having a step shape on the lower surface,
It is possible to configure by applying the present invention.

[0036]

As described above, in the powder compacting apparatus for an engine according to the first aspect of the present invention, the pressing force in the direction toward the yoke plate is applied to the piston of the air cylinder to which the core rod is connected. A check valve that allows the air flow in the direction toward the air cylinder to the air supply line that supplies compressed air to the cylinder chamber on the opposite side of the yoke plate from the piston, while blocking the flow in the opposite direction Is provided.

Therefore, when the biting force on the core rod is reduced during the removal of the green compact,
Since the extraction force with respect to the core rod is increased, the switching from the integral operation of the core rod with the powder compact to the extraction operation can be obtained more reliably. As a result, there is an effect that the extracting operation of the core rod can be performed more stably without generating cracks or the like in the green compact.

According to a second aspect of the present invention, an auxiliary cylinder is provided between the base plate and the die plate, the auxiliary cylinder including an auxiliary cylinder chamber having a reduced internal volume when the two plates approach each other. In addition, a branch line branched from the air cylinder side of the check valve in the air supply line is connected to the auxiliary cylinder chamber.

Therefore, during the operation of extracting the core rod, an operation state of a higher extraction force can be obtained, so that the operation of extracting the core rod can be more reliably generated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a die set of a compacting apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a die set showing an operation state in a powder compacting process by the powder compacting apparatus.

FIG. 3 is a longitudinal sectional view of a die set showing a state in the middle of taking out a green compact after the green compact.

FIG. 4 is a longitudinal sectional view of a die set showing a state at the time of completion of taking out of the green compact.

[Explanation of symbols]

 2 Base plate 3 Die plate 4 Yoke plate 6 Dice 7 Molding hole 8 Core rod 11 Air cylinder 12 Piston 15 Lower punch 21 Air supply line 22 Check valve 24 Auxiliary cylinder 28 Branch line 30a

Claims (2)

(57) [Scope of request for utility model registration] 1. A compacting method in a molding hole of a die mounted on a die plate, comprising a base plate, a die plate movable relative to the base plate, and a yoke plate moving integrally with the die plate. A cylindrical lower punch that covers the space from the base plate side is fixed to the base plate, and a base end side of the core rod, which penetrates the lower punch and whose distal end is located in the molding hole, is located in the air cylinder attached to the yoke plate. An air supply line for supplying compressed air to a cylinder chamber on the opposite side of the yoke plate from the piston so as to apply a pressing force in a direction toward the yoke plate to the piston,
A powder compacting device in which a compact formed in a compacting space is extruded by a lower punch from a molding hole by relatively moving the die plate in a direction toward the base plate, and the air supply is performed. A powder compacting device, characterized in that a check valve for allowing air flow in the direction toward the air cylinder and blocking the flow in the opposite direction is interposed in the line. 2. An auxiliary cylinder having a built-in auxiliary cylinder chamber whose internal volume is reduced when the two plates approach each other is provided between the base plate and the die plate. 2. The supply line is connected to a branch line branched from the air cylinder side of the check valve.
A compacting apparatus as described in the above.