JPH0239679Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of the lower punch mechanism in a powder molding die set for compression molding powder material into a complicated shape with steps or flanges.

[Conventional technology]

When compression molding a molded product A with a complicated shape as shown in FIG. 3, if you try to mold each part of the molded product by applying uniform pressure (for example, 4 to 7 tons/cm ³ ),
For example, in the case of the figure, lower punches 1, 2, and 3 are divided into three parts and arranged concentrically. Normally, the outer punches have shorter lengths in the compression direction than the inner punches, so each lower punch There is a difference in the amount of axial deflection (hereinafter referred to simply as the amount of deflection) due to the molding pressure, which causes cracks to occur in the molded product during extrusion.

Therefore, in order to correct the difference in the amount of deflection due to the difference in punch length, conventionally, each lower punch (2 and 3 in the figure) except the lower punch 1 which is supported by the base 4 and has the largest amount of deflection, and An adapter 7 having a lower rigidity than the lower punch plates 5 and 6 is interposed between the lower punch plates 5 and 6, which are indirectly supported by the base 4 through non-contact blocks and support pins, and supports the lower punches. The deflection caused by the molding pressure compensated for the lack of deflection of the lower punches 2 and 3, and the amount of displacement in the tree direction of the upper surfaces of the punches 1, 2, and 3 was made uniform, thereby preventing cracks caused by the difference in the amount of deflection of the lower punches. In the figure, 8 indicates a die with a cavity, 9 indicates a core rod, and B indicates an upper punch.

In addition, as shown in Japanese Patent Application Laid-Open No. 15099/1983, a technique has been proposed in which an elastic body such as urethane rubber is installed between the lower punch and the lower punch plate to correct the amount of deflection of each lower punch. There is.

[The problem that the idea aims to solve]

However, in the former method that has been adopted conventionally, as the cross-sectional area of the outer lower punches (2 and 3 in the figure) increases, the difference in the amount of deflection increases. There will be cases where it cannot be lowered. In other words, if the rigidity of the adapter is lowered by reducing the wall thickness to a point where sufficient deflection can be obtained, the rigidity necessary to receive the molding pressure may be insufficient and the adapter may crack due to the force applied to the punch. come.

On the other hand, the technology shown in JP-A-60-15099 is
This not only complicates the lower punch mechanism but also increases the number of parts, and since the elastic bodies are scattered around the punch, it is conceivable that the straightness of the lower punch will be adversely affected.

[Means to solve the problem]

In order to eliminate the above-mentioned problems, the present invention has developed the innermost lower punch 1, which has the longest axial dimension and the maximum amount of axial deflection under forming pressure, as shown in Fig. 1.
is supported by a base 4, and the outer lower punches 2 and 3 are arranged concentrically around the outer periphery of the punch 1, and an adapter 7 is attached to the outer periphery of the lower punch plates 5 and 6, which are indirectly supported by the base. The adapter 7 is supported on the inner peripheral side of the adapter, and the adapter 7 has its rigidity as a base.
In the lower punch mechanism, which is smaller than the rigidity of the lower punch plate, the plate support member (the above-mentioned block and support pin) between the base and the lower punch plate, and is sized to withstand molding pressure, the outer lower punches 2 and 3 These supporting adapters 7 each have a circular shape 10a concentric with the lower punch.
A plate 10 having a lower rigidity than that of the plate 10 is interposed, and a circular hole 19a is opened at the joint interface between the plate 10 and the adapter 7, and the dimension in the punch axial direction is gradually increased from the open end to the outside of the support area of the outer lower punch. A gap 11 that expands concentrically while being compressed is provided, and when the difference in the axial upper area displacement due to the bending of the punch and adapter at the forming pressure between the lower punch 1 and the outer lower punch determined in the design is δ, each Lower outer punch 2,
For No. 3, the axial dimension at the open end on the circular hole side of the gap 11 is made to match δ determined for each outer lower punch. The figure shows the maximum dimension of the gap corresponding to 2, assuming that the difference in top surface displacement between 1 and 2 is δ ₁ and the difference in top surface displacement between 1 and 3 is δ ₂ . The maximum dimension of the gap in the portion corresponding to δ ₁ and 3 is set to δ ₂ .

Note that, if the amount of axial deflection of the base 4 under the forming pressure is substantially 0, the amount of displacement of the upper surface in the axial direction due to the forming pressure of the lower punch 1 is expressed by the amount of axial deflection of the base 4 itself. On the other hand, the amount of displacement of the upper surface of the lower outer punch 2 is the sum of the amount of axial deflection of the lower punch 2 itself and the amount of axial deflection of the adapter supporting the lower punch 2, if the drop due to the deflection of the lower punch plate is zero. In the case of a general die set, the base and lower punch plate are
Since it is designed so that almost no deflection occurs due to molding pressure, the maximum axial dimension of the gap 11 should be determined by subtracting the deflection amount of 2 from the deflection amount of 1 and the deflection of the adapter that supported it. become. This idea is the same for Punch 3 as well.

Note that if the adapter is given rigidity to withstand molding pressure, the amount of axial deflection will be smaller than the difference in the amount of axial deflection between the innermost lower punch and the outermost lower punch, so the above δ
is never a negative value.

Here, in the illustrated lower punch, a conical surface 10b is provided around the circular hole of the plate 10, and a gap 10b is provided to create a gap 11.
As shown by the chain line, the adapter 7 may be provided with a conical surface 7a, or both the plate 10 and the adapter 7 may be provided with conical surfaces.

According to this structure, the plate 10 compensates for the amount of supplementary deflection that cannot be compensated for by the adapter 7, which has the required rigidity. That is, as shown in FIG. 2 (the amount of deformation in this figure shows an extreme example), when pressurizing, the outer lower punch 2, the adapter 7 that supported it, and the plate 10 between 2 and 7 are integrated. As a result, the gap 11 is completely filled (the same applies to the lower punch 3 side), thereby compensating for the lack of deflection of the outer lower punches 2 and 3, which are shorter in the axial direction.
Further, the plate 10 is prevented from being destroyed by the molding pressure with the help of the adapter 7. Then, when the compression molding is completed and the pressure is released, the lower outer punches 2 and 3, the adapter 7, and the plate 10, which are bent during pressurization, return to their original states by their respective elastic forces. Therefore,
Even if uniform molding pressure is applied to each lower punch, there is no fear of cracks occurring in the molded product during extrusion.

In addition, the gap 11 is formed between the plate 10 and the adapter 7.
It can be easily created by simply adding a conical surface to the
There is no need to complicate the lower punch mechanism.

Furthermore, especially when the plate 10 is provided with a conical surface to create a gap, the size of the gap can be changed simply by replacing the plate 10, so changes in the length of the lower punch can be easily accommodated.

The above explanation was made assuming that the outer lower punches are two, 2 and 3, and the lower punch mechanism is composed of a total of three lower punches, including the inner lower punch. This also applies to the case where the lower punch mechanism is constructed by combining two or more lower punches arranged concentrically.

A simple calculation example of the rigidity of the plate 10 and the size of the gap 11 will be shown below with reference to FIG. Here, it is assumed that the punch 1 is also supported by a disk made of a heat-treated alloy steel plate made of the same material as the punch 2. The support disk 1 is numbered 20, and the support disk 2 is numbered 30. Punch 1 has a total length of L, deflection amount = △L, punch 2 has a total length of 1, deflection amount △L, and the disc 30 has a thickness of △L.
h ₁ , amount of deflection = W _e , thickness of the disk 20 h ₂ , amount of deflection =
Let it be W _L. The axial and radial dimensions are shown in the figure.

Assuming that pressure is applied to the inner periphery of the disks 20 and 30 in this way, the deflection of the punch 2 is △l=l・P/E The deflection of the disk 30 is W _e =α _q1 P・S ₁・a ₁ ² /Eh ₁ ^3The stress of the disk 30 is σ _e =β _q1 P・S ₁ /h ₁ ^3Here , for the disk 30, the pressure receiving area S ₁ =
π/4 (70 ² - 60 ² ) = 1021 mm ² , E (Young's modulus) = 21000 Kg/mm ² , 2a ₁ = 100, _{2b 1} = 60, deflection coefficient α _q1 and stress coefficient at b ₁ /a ₁ β _q1 is calculated from Figures 6, 54 and 6, 58 of Machine Design Handbook P765, σ _e = 40.0Kg/mm ² , and that of disk 20 is calculated from the same formula as ▽L = 0.83, W _L =
0.05, σ _L =102Kg/mm ² . Therefore, if the design can be made in this manner, each disk will have a sufficiently small amount of deflection and stress and will not be damaged. However, in this case, 1 and 2
The difference in top surface displacement is δ=△L+W _L −(△l+W _e )
= 0.51, which causes cracks in the molded product during extrusion. Therefore, if we try to absorb this difference δ by increasing W _e , we get It becomes necessary to reduce the plate thickness h ₁ until the plate thickness h 1 becomes thinner, and at this time σ _e becomes 215 Kg/mm ² and 30 is damaged.

Therefore, as shown in the figure, a plate 10 with a gap of t=10, outer diameter 100, inner diameter 60, and δ0.51 between 2 and 30
If we include 2b/2a=0.6, we get a deflection of 10,
Since the stress coefficients are α _q = 0.6 and β _q = 1.4, from σ′ = 0.6 × P × 50 ² /21000 × 10 ³ , plate 10 becomes δ+ at equivalent pressure P = 7700 Kg.
The plate is deflected by We, and the stress on the plate is σ=107.8Kg/ ^mm2 . That is, for the force S ₁・P = 71.5×10 ³ Kg applied to the punch end face, the force of the disk 30
It is possible to adjust the difference in displacement of the upper surface in the axial direction due to the molding pressure on the upper surface of the lower punch without breaking the plate 10 while keeping h ₁ =50 mm.

〔effect〕

As described above, according to the present invention, among the plurality of lower punches arranged concentrically, a lower punch located on the outside and a lower punch plate interposed between the lower punch and the lower punch plate to compensate for the lack of deflection of that punch. A plate is provided between the adapter and the adapter, and a gap is provided between the plate and the adapter so that the amount of deflection that cannot be compensated for by the adapter is ensured by the deflection of the plate, thereby ensuring the necessary rigidity of the adapter. This makes it possible to equalize the amount of upper surface displacement due to the deflection of each punch when pressurized, and therefore avoids generating abnormal pressure on the molded product due to differences in the springs of the punches due to the release of this pressure during extrusion. , cracks in molded products caused by abnormal pressure are prevented.

In addition, since the gap between the plate and the adapter can be easily created as described above, the lower punch mechanism is not complicated.Furthermore, since the plate supports the lower punch around the entire circumference, the lower punch can move in a straight line. It does not make things worse.

In addition, since the size of the gap can be changed simply by replacing the plate or adapter, it is also easy to deal with changes in punch length.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an embodiment of the present invention in an unloaded state, Fig. 2 is a cross-sectional view of the pressurized state, Fig. 3 is a cross-sectional view of essential parts showing an example of a conventional lower punch mechanism, and Fig. FIG. 4 is a diagram showing an example of calculation for determining δ and plate rigidity. 1... Innermost lower punch, 2, 3... Outer lower punch, 4... Base, 5, 6... Lower punch plate, 7... Adapter, 7a... Conical surface, 10...
Plate, 10a...Circular hole, 10b...Conical surface, 11...Gap.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) Among the plurality of lower punches opposed to the upper punch, the innermost lower punch, which has the longest axial dimension and the maximum amount of axial deflection under forming pressure, is used as the base. n
The outer lower punches (n≧1) are each attached with an adapter supported on the outer periphery of the n lower punch plates above the base, which are indirectly supported by the base, and are supported on the inner peripheral side of the adapter. , and the adapter uses its rigidity as the base, the lower punch plate,
The rigidity of the plate support member between the base and the lower punch plate is smaller than the rigidity of the plate supporting member, and the size is strong enough to withstand the molding pressure, so that the amount of axial deflection under the molding pressure is greater than the difference in the amount of axial deflection between the innermost lower punch and the outer lower punch. In the lower punch mechanism of a powder compacting die set that is kept small, a plate with lower rigidity than the adapter having a circular hole concentric with the lower punch is interposed between the outer lower punch and the adapter that supports it. Then, at the joint interface between this plate and the adapter, a gap is provided that opens into the circular hole and expands concentrically from the open end to outside the support area of the outer lower punch while gradually reducing the dimension in the punch axis direction. Punching with forming pressure of inner lower punch and outer lower punch,
Letting δ be the difference in the amount of displacement of the upper surface in the axial direction due to the bending of the adapter, the axial dimension at the open end on the circular hole side of the above gap for each lower outer punch is made to match δ determined for each lower outer punch. Features a lower punch mechanism in a die set for powder molding. (2) The lower part of the die set for powder molding according to claim (1) of the utility model registration claim, wherein the gap is created by providing a conical surface on the joint surface of the plate, the adapter, or both. Punch mechanism.