JPS62286641A - Multiple interference fit metallic die - Google Patents

Abstract

PURPOSE:To heighten an allowable internal pressure by providing a peripheral direction stress softening means on a clamping ring, and also, forming it to a shape for incresing a compressive force by varying its length in the axial direction. CONSTITUTION:A clamping ring 3 is divided completely by a gap 6, and generation of a stress in the peripheral direction for repelling the clamping from clamping rings 1, 2 is relaxed, therefore, the clamping force from the clamping rings 1, 2 is not attenuated by a stress generated in the ring 3 but transferred efficiently to an insert 4. As for the clamping ring 3, when its length in the axial direction is denoted as Ho and Hi, in the outside peripheral side and the inside peripheral side, respedtively, and its diameter is denoted as Do and Di, in the outside peripheral side and the inside peripheral side, respectively, a compressive force Pi which is generated when a compressive force Pi has been received in the outside peripheral side becomes Pi>Po since Do>Di, and also, Ho>Hi. In this way, when the ring 3 is clamped by the clamping rings 1, 2, the compressive force is increased, a pre-load is given by clamping more strongly the insert 4, and an allowable internal pressure of a multiple interference fit metallic die is further raised.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a multiple interference fit mold used under high pressure, It can be used as a guide.

(Background technology and common points) In general, molds for plastic working such as cold forging gouers are required to have a high allowable working pressure, that is, a high allowable internal pressure to perform processing at considerably high pressures. . In particular, if they have the same allowable internal pressure, it is desirable to use less material and have smaller outer dimensions from the viewpoint of economy and workability. Multiple interference fit molds are often used.

This multiple interference fit mold includes a plurality of tightening rings 1 each being a tightening cylinder fitted by interference fit.
, 2.3, and an insert 4 which is a central cylinder fitted into the innermost side of these tightening cylinders by interference fit, and a die hole 5 is provided in the center of the insert 4. In the multiple interference fit mold configured in this way, by preloading the insert 4 from the outside with the tightening force of the tightening ring 1.2°3, the stress in the circumferential direction on the surface of the die hole 5 is reduced to the compression side. This prevents the stress in the circumferential direction of the die hole 5 from becoming excessive on the tensile side due to the high pressure applied inside the die hole 5 during processing, and prevents the stress of the insert 4 from exceeding the yield stress to maintain the mold. This prevents breakage and the like, thereby making it possible to increase the allowable internal pressure within the die hole 5 compared to a single mold.

A large number of studies have been published regarding the design of such multiple interference fit molds. Once determined, the allowable internal pressure when configured based on optimal conditions can be known in advance. On the contrary, by appropriately selecting these elements, the allowable internal pressure can be further increased. However, when high-performance materials are used to improve mechanical properties, the cost of the materials increases, leading to a decrease in economic efficiency. In addition, there is a limit to the number of combinations of tightening cylinders that can be used while maintaining the same outer diameter, and furthermore, there is a problem in that increasing the outer diameter leads to a decrease in workability.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multiple interference fit cylinder having a higher allowable internal pressure than conventional cylinders.

[Means and effects for solving the problem] In the present invention, two or more clamping cylinders combined as a multiple interference fit mold and a central cylinder fitted inside these are provided, and the above-mentioned At least one of the tightening cylinders, excluding the outermost one, is provided with a circumferential stress relaxation means consisting of an axial cut, and the axis of the surface where this cylinder and the inner cylinder come into pressure contact with each other is provided. The length in the axial direction is configured to be shorter than the length in the axial direction of the surface where this cylindrical body and the outer cylindrical body come into pressure contact with each other.

In the multiple interference fit mold configured in this way,
The circumferential stress relaxation means provided on the cylindrical body suppresses the generation of circumferential stress horns that are generated on the cylindrical body in response to the hoof-clamping force from the cylindrical body circumscribing the cylindrical body. , the tightening force is efficiently transmitted to the cylindrical body inscribed in the cylindrical body without attenuation.

In addition, by making the axial length of the surface where the cylinder and the inner cylinder come into pressure contact with each other shorter than the length of the surface where the cylinder and the outer cylinder come into pressure contact with each other, the abutting cylinder can be By making the area of the inner pressure contact surface smaller than the area of the outer pressure contact surface, when transmitting the tightening force built up on the outer pressure contact surface to the inner pressure contact surface, the compressive force per unit area is transferred to the inner pressure contact surface. and the outside area.

The present invention aims to improve the allowable internal pressure in the die hole by increasing the preload that can be applied to the central cylindrical body.

C Embodiment] An embodiment of the present invention will be described with reference to the drawings. Note that, for the sake of simplicity, the same names are used for the same parts as in the conventional example described above.

The multiple interference fit mold shown in FIG. 1 and FIG.
3 and an insert 4 which is a central cylindrical body,
The tightening ring 1 and the tightening ring 2 are respectively compressed. Further, an insert 4 is tightly fitted inside the tightening ring 3, and a die hole 5 is provided in the center of the insert 4, which passes through it vertically.

The upper and lower end surfaces of the tightening ring 3 immediately outside the insert 4 are each provided with a conical surface shape 3A, and the tightening dimension is such that the axial length Hi of the inner surface of the ring 3 is the same as that of the outer surface. It is formed to be shorter than the axial length Ho. Further, the tightening ring 1.2 has an axial length equal to HO, the insert 4 has an axial length equal to Hi, and the tightening ring 3 has an axial length of the surface that presses against the insert 4. The length Hi is configured to be shorter than the axial length HO of the surface that comes into pressure contact with the tightening ring 2.

Further, the tightening ring 3 is provided with a large number of axial cuts 6 as circumferential stress relaxation means, and the tightening ring 3 is completely divided by the cuts 6. Each of the interference fits described above is performed based on the usual calculation method for the optimum fit diameter and optimum interference margin, and the tightening ring 3 is fitted into the tightening ring 2 by inserting a spacer or the like in the cut 6 at one end. After that, it is completely press-fitted except for the spacer, so that the gaps between the cuts 6 are made equal.

In this embodiment configured in this way, the tightening force from the tightening rings 1 and 2 is transmitted to the insert 4 via the tightening ring 3, and a preload is applied to the insert 4. That is, the tightening ring 3 is completely divided by the cut 6 and does not itself tighten the insert 4, but the generation of circumferential stress that opposes the tightening from the tightening ring 1.2 is alleviated. The tightening force from the tightening rings 1 and 2 is not attenuated by the stress generated in the tightening ring 3, and is efficiently transmitted to the insert 4.

Here, as shown in FIG. 3, the length of the tightening ring 3 in the axial direction is Hi on the outer peripheral side and on the inner peripheral side of HO1,
If the diameter is Do on the outer circumferential side and Di on the inner circumferential side, the area So of the outer circumferential surface and the area Si of the inner circumferential surface are π 5o=-(Do)" ・Ho (1)5i--
(Di)2.H: Represented by (2). Therefore, assuming that there is no attenuation of the tightening force in the tightening ring 3, the compressive force P1 generated on the inner circumferential side when the outer circumferential side receives the compressive force po due to the tightening force from the tightening rings 1 and 2 is expressed as , since Do>Di and Ho>Hi, Pi>
Becomes Po. In this way, when the tightening ring 3 is tightened to the tightening ring 1.2, the compressive force is increased in accordance with the area ratio of the inner and outer circumferences, and the insert 4 is tightened more strongly and preloaded.

According to this embodiment, a larger preload can be applied to the insert 4 without changing the outer diameter dimension, material, number of combinations, etc. compared to the conventional multiple interference fit mold, and the This has the effect of further increasing the allowable internal pressure of the mold.

In addition, if the allowable internal pressure is the same, it can be made smaller and lighter, improving workability and economic efficiency, and even with the same outer diameter, it is possible to reduce the size and weight.
can be made larger, expanding the range of products that can be processed with molds of the same diameter.

Furthermore, since the multiple interference fit mold of this example can be easily replaced with the conventional multiple interference fit mold, the processing range of forged products, etc. that can be manufactured using the same press equipment, etc. can be reduced. It also has the effect of being able to be expanded.

In the first embodiment, the tightening ring 3 is provided with a cut 6 as a circumferential stress relaxation means, and the tightening ring 3 is completely divided. However, in the second embodiment shown in FIG. , a slit 7 is provided in the tightening ring 3 having a conical surface shape 3A on the upper and lower end surfaces, and the tightening ring 3 is not completely divided.

In FIG. 4, the tightening ring 3 is provided with a slit 7 as a circumferential stress relaxation means, and the tightening ring 3 is cut in the axial direction by the slit 7 except for a part. It is continuous and not completely divided. Note that the other configurations are the same as those of the first embodiment, so explanations will be omitted. According to this embodiment, the tightening ring 3 is divided in the axial direction to alleviate stress generation in the circumferential direction, and in addition to obtaining the same effect as the first embodiment, the tightening ring 3 Since it is not completely divided, it has the effect that the tight fitting work is significantly easier.

Furthermore, in the third embodiment shown in FIG. 5, the tightening ring 3 having a conical surface shape 3A on the upper and lower end surfaces is provided with only one cut 6 that completely cuts off the tightening ring 3 in the axial direction. The stress in the circumferential direction is alleviated without completely dividing the ring 3, and the effect is similar to that of the embodiment 'WJ2'. However, in terms of stress relaxation in the circumferential direction, the first embodiment in which the tightening ring 3 is completely divided is more effective than the second and third embodiments.

As described above, the number and width of the cuts 6 or slits 7 are not particularly limited, and in short, the spacing can be maintained even when tightened from the outer periphery, and the generation of stress in the circumferential direction of the cylindrical body can be alleviated. This means providing a cut 6 or slit 7 like this.

On the other hand, in each of the above embodiments, the conical surface shape 34 was provided on the upper end surface and the lower end surface of the tightening ring 3, but this may be provided only on the upper end surface or the lower end surface.
A similar effect can be obtained by forming the tightening ring 3 so that the length in the axial direction on the inner circumferential side is shorter than the length in the axial direction on the outer circumferential side.

Further, in each of the above embodiments, the conical surface shape 3A is provided to change the length of the tightening ring 3 in the axial direction linearly and continuously. For example, as a fourth embodiment, as shown in FIG. 6, substantially spherical shapes 3B may be provided on the upper and lower end surfaces of the tightening ring 3 to change the lengths of the inner and outer circumferences of the tightening ring 3 in the axial direction. .

Furthermore, in the fifth embodiment shown in FIG. 7, the conical surface shape 3A, etc. are omitted, and the axial length of the tightening ring 3 itself is changed to HO on both the inner and outer circumferences, and the inscribed insert 4 is
If the length in the axial direction is Hi, the length in the axial direction of the surface 3C in pressure contact with the insert 4 is Hi, so that the same effects as in each of the embodiments described above can be obtained.

In this way, the dimensions and shape of the tightening ring 3 are not limited to those in each of the above-mentioned embodiments. This means that the length of the groove bottom is shorter than the length in the axial direction of the surface that comes into pressure contact with the outer cylindrical body.

In addition, in each of the above embodiments, the tightening ring 1.2
．． 3, and the number of combinations of tightening cylinders is set to four, but the present invention is not limited to this, and the present invention is to provide two or more plural tightening cylinders.

In addition, in each of the above embodiments, the axial length of the surface of the tightening ring 3, which is the innermost of the tightening cylindrical bodies, is in pressure contact with the inner cylindrical body, and the axial length of the surface in pressure contact with the outer cylindrical body is Although the tightening ring 3 is provided with cuts 6 or slits 7 as circumferential stress relaxation means, the tightening ring 2 may be formed in this way. This means that one of the cylindrical bodies excluding the cylindrical body is formed in the above-mentioned shape. However, when it is applied to the cylinder closer to the inner insert 4, it is more effective in alleviating the stress in the circumferential direction that attenuates the tightening force, and has the effect of improving the allowable internal pressure.

〔Effect of the invention〕

As mentioned above, according to the multiple interference fit mold of the present invention, a predetermined tightening ring is provided with a circumferential stress relaxation means and is shaped to increase compressive force by varying the length in the axial direction. This has the effect that the allowable internal pressure can be further increased compared to molds of the same size.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the structure of a first embodiment of the present invention, FIG. 2 is a sectional view showing the embodiment, FIG. 3 is a perspective view showing the main parts of the embodiment, and FIG. 5 is a perspective view showing the main part of the second embodiment of the invention, FIG. 5 is a perspective view showing the main part of the third embodiment of the invention, and FIG. 7 is a sectional view showing a fifth embodiment of the present invention, and FIG. 8 is an exploded perspective view showing the configuration of a conventional example. 1.2.3... Tightening ring as a tightening cylindrical body, 4... Insert as a central cylindrical body, 5... Gouging hole, 6... Cut as a circumferential direction stress relaxation means, 7
...Slits as a means of stress relaxation in the circumferential direction.

Claims (4)

[Claims] (1) In a multiple interference fit mold comprising a plurality of tightening cylinders coaxially fitted together and a central cylinder fitted into the innermost side of these cylinders, the outermost one of the tightening cylinders At least one cylinder other than the cylinder is provided with a circumferential stress relaxation means consisting of a cut formed in the axial direction, and the axis of the surface where this cylinder and the inner cylinder are pressed against each other is provided. A multiple interference fit mold characterized in that the length in the axial direction is shorter than the length in the axial direction of the surface where the cylindrical body and the outer cylindrical body press against each other. (2) The multiple interference fit mold according to claim 1, wherein the circumferential stress relaxation means comprises a cut that completely divides the cylindrical body in the axial direction. (3) The multiple interference fit mold according to claim 1, wherein the cylindrical stress relaxation means comprises a slit that does not completely divide the cylindrical body in the axial direction. (4) In any one of claims 1 to 3, the cylindrical body provided with the circumferential stress relaxation means is such that the axial length of the cylindrical body itself on the inner circumferential side is on the outer circumferential side. A multiple interference fit mold characterized by being formed shorter than the length in the axial direction.