JPS611415A - Method of forming die for extrusion - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of forming an extrusion die, such as a die used for extruding aluminum.

[Technical background of the invention and its problems] In an extrusion die having a substantially constant axial contact depth between an inlet and an outlet, the amount of material passing through each part of the die aperture varies depending on the shape of the die aperture. It is known that the resistances are different. For example, the resistance to flow between two opposing parallel walls is generally inversely proportional to the spacing between the walls. Furthermore, the extrusion pressure essentially varies along the die opening surface. This variation in resistance to flow and
Variations in extrusion pressure in different parts of the die aperture create different flow rates in the extruded material, which creates severe internal stresses in the material. Therefore, it is desirable to design the extrusion die so that the flow rate of the extruded material is substantially uniform over the entire surface of the aperture.

It is known that the flow resistance in a section of an extrusion die can be reduced by reducing the axial abutment depth of the apertures and increased by increasing the aperture depth. Therefore, in areas of the aperture shape where the flow resistance is high,
It has also been customary to design extrusion dies to reduce the depth of contact in areas where the extrusion pressure is lower. Accurate calculation of the welding length requires skill and experience on the part of the die designer.Even a good designer is unlikely to be able to produce a satisfactory extrusion die without trial and modification. . In practice, it may be necessary to perform a number of die tests, each time changing the abutment depth, before a satisfactory design is achieved.

This is clearly a time-consuming trap that yields only approximate results.

European Patent Application No. 83302931.7 (Publication No. 0.095,359) describes the abutment required at each part of the aperture of an extrusion die in order to produce a substantially uniform flow rate over the entire surface of the aperture. A simple method for determining depth is described and claimed. In certain methods described in the said patent application, an extrusion aperture is formed in a piece of die material by, for example, spark erosion, and the flowable material is then partially forced into an extrusion abatement, which causes the material to The tip surface is deformed in the extrusion direction.

Therefore, if the exposed surfaces inside the extruded aperture are removed by chemical or galvanic attack, the active axial abutment depth at any point along the outer circumference of the aperture will be reduced by the flowable material at that point. Determined by the depth of penetration. Since the extent to which flowable material flows into the extrusion abateer is inversely proportional to the flow resistance at that section, the axial abutment depth at that section of the finishing die is also inversely proportional to the flow resistance, and therefore, this When the die is used for extrusion, a substantially uniform flow rate occurs across the die aperture.

[Purpose of the invention]

The present invention consists in providing an improvement on the method described and claimed in the aforementioned European patent application.

As mentioned above, the difference in flow rate in material extruded through a die, whatever the geometry of the die, depends in part on the overall variation in extrusion pressure across the guide surface. It has been discovered that the method described in the aforementioned patent application does not adequately compensate for this overall extrusion pressure variation (known as the "macro flow profile") in some circumstances, and the method of the present invention The object of the present invention is to provide an improved method for more effectively compensating for such fluctuations.

[Summary of the invention]

Accordingly, the present invention comprises the steps of: forming an extrusion aperture in a die aperture; forcing a flowable material at least partially through the extrusion aperture such that the leading surface of the material is deformed in the extrusion direction; reshaping the piece of die material so that the abutment depth of the extrusion aperture at any location along the circumference of the extrusion aperture corresponds to the deformation of the distal surface of the flowable material at this portion; A method of forming an extrusion die is provided which includes the additional step of adjusting the depth of axial abutment at each section along the circumference by an amount that depends on the distance of the section from the center of the piece of die material. .

According to one embodiment of the invention, before reshaping the die material piece in response to the deformation of the flowable material as described above, the die material piece is This adjustment is effected by profiling the inlet end face of the piece of die material to reduce the axial thickness of the die material.

The inlet end face of the die piece of material is profiled by machining.

In another embodiment according to the invention, before the step of forcing the flowable material at least partially into the extrusion aperture, an extension member having an aperture aligned with the extrusion aperture of the die material piece is inserted into the inlet of the die material piece. Adjustment of the axial abutment depth is effected by being attached to the entire end face, and the extension member has an axial thickness that increases in proportion to the distance from the center of the die, so that the flowable material The axial depth at which the flowable material plunges into the piece of die material at any portion when pushed through the extension member and at least a portion of the extrusion opening of the piece of die material is the axial depth of the extension member at that portion. The extension member is then removed from the die material piece before using the die material member in an extrusion process.

The extrusion member may be a preform attached to the die piece of material or may be in-situ with respect to the die piece of material.
n 5 itu ) can be a cast part.

In each case, this extension member is made of wax or synthetic plastic material, for example.

If the piece of die material is to be reshaped by chemical or electrolytic erosion, the extension member can be left in contact with the piece of die material to protect the inlet end face of the piece of die material during the erosion process.

In either structure described above, the adjustment of the axial abutment depth can vary linearly from the center of the die to the outer circumference. For example, the ratio of the reduction in axial abutment depth to the distance from the die center may be in the range of 1:18 to 1:12.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

EMBODIMENT OF THE INVENTION Referring to FIG. 1, a piece of die material 10 is formed with an extrusion aperture 11 having a central cylindrical portion 12 extending from the center into two narrow parallel side wall arms. 13 is extended. Figure 1 shows a very simple extrusion aperture configuration for illustration only; the principles of the invention apply to extrusion apertures of any complex shape, including extrusion apertures of hollow profiles. It will be understood that this will happen.

Aperture 110 dimensions are calculated in a conventional manner to allow shrinkage and bending of the die material during the extrusion process. Generally, one aperture is electrical discharge machined into a piece of die material and then cleaned and polished.

As best seen in FIG. 2, the die piece 10 has a constant axial thickness so that the extrusion aperture initially has a constant axial abutment depth.

When using the die, the resistance to flow within the cylindrical portion 12 of the aperture is less than the resistance to flow between adjacent side walls of the arm portion 13.

The resistance to flow at the outer ends of the arms 13 is even greater due to the frictional resistance of the end walls of each arm. Accordingly, material extruded through a die of the shape shown in FIG. 2 experiences non-uniform flow and is subject to undesirable internal stresses. Figures 3 to 5 illustrate the known method described in the aforementioned European Patent Application No. 83302937.7 for adjusting the axial abutment depth of an aperture to produce a substantially uniform flow. .

Referring to FIG. 3, a suitable flowable compound 14 is forced partially into the extrusion aperture 11 by a piston (not shown) simulating the action of an extrusion press. To detect and display when this compound has been injected to a predetermined depth inside the aperture,
A probe (not shown) is placed inside the annular chair, and when the compound reaches this probe, one piston is stopped and extrusion is interrupted.

As is clear from Figure 3, due to the variation in the resistance to flow in each part of the dice,
The tip surface of the compound 14 is deformed in the axial direction, and the cylindrical part 1
The portion of the compound passing through the arm portion 13 moves further than the portion of the compound passing through the arm portion 13. Thus, when the piston is stopped, the green of the distal surface of the compound contacts the inner surface of the annotation II along the profile 16 between the inlet 17 and the outlet 15 of the extrusion aperture 11.

According to the basic method, then the profile, 16 and the exit 15
In the area between Depending on the case, the flowable compound 14 is preferably an acid-resistant or non-conductive material in order to prevent corrosion of the die annular chair part that is in contact with the flowable material. The outer surface of the die is also coated or covered with an acid-resistant or electrically non-conductive material. Other details of this treatment are described in the European Patent Application mentioned above.

When the corrosion treatment was completed as shown in FIG. 5, the effective contact area of the die was maintained by the compound 14.
Only the portions have different axial abutment depths. In this way, the axial depth of abutment was automatically adjusted according to the flow rate through the green die material piece, so that the flow was substantially uniform throughout the extrusion annotation, and thus This greatly reduces the internal stress in the extrudate produced by the die.

However, in some cases automatic adjustment of the axial abutment depth by this method is insufficient to cause a variation in the overall extrusion pressure across the cross-section of the die aperture, whatever the shape of the die. It was discovered that. That is, the overall extrusion pressure peaks at the center of the die and decreases away from the center of the die. FIG. 6 shows one method according to the invention for compensating for such effects.

As seen in FIG. 6, the inlet end face 19 of the piece of die material is machined to form a circular indentation 20 before reshaping the die annotation by the method described in FIGS. 1-5. The bottom surface 21 of the circular depression 20 is inclined in the extrusion direction from the center 22 of the die to the outer periphery thereof. The effect of machining the end face of the die in this manner is to reduce the effective axial contact depth of the die at each portion of the outer periphery of the annotation by an increment corresponding to the distance to this portion of the die center 22. be. In this way, at the die center, where the extrusion pressure is highest, there is little or no reduction in the abutment depth, and, in contrast, at the die periphery, where the extrusion pressure is lower than at the center. , the contact depth is greatly reduced compared to the center,
Correspondingly, the reduction in resistance to flow is greater.

Therefore, when the flowable compound 14 is forced against the inlet face of the die, since the leading face of this compound is essentially flat, it first contacts the center of the die aperture and only then contacts the outside of the die. come into contact with the part. Therefore,
After the partial injection of compound into the die aperture is completed, the distance that the compound has penetrated into the aperture at any location has been reduced by an amount equal to the axial depth of the recess 20 in that portion. The recesses 20 have a depth that increases towards the outer circumference of the die piece of material, so that the axial abutment depth correspondingly decreases with distance from the center of the die.

It will be appreciated that a similar effect can be obtained by machining a recess similar to the indentation 20 in the inlet end face of the die material piece shown in FIG. In this case, however, care must be taken not to reduce the total contact depth of the die material pieces in any part by forming the depressions.

In practice, the inclination angle of the bottom surface 21 of the recess 20 is such that the ratio of the degree of reduction of the axial contact depth to the distance from the die center is 1:
It has been found that it is preferable to have a ratio within the range of 1:18 to 1:12. Although the sloped surface of the bottom of the recess is illustrated as a straight line, this bottom may in some cases be curved.

7 to 9 show other embodiments of the invention.

According to this method, an extension member 23 is attached to the inner end surface 19 of the die material piece 10 before carrying out the method of FIGS. 1 to 5. This extension member 23 is formed with an aperture iia in exact alignment with the aperture 11 of the piece of die material. The depth decreases with increasing distance from the centerline 22 of the piece of die material.The slope of the bottom of this depression ranges from 1:18 to 1:12, as in FIG.

The extension member 23 can be preformed as a unit and attached to the piece of die material 10, or it can be formed in situ to the piece of die material 10. The extension member can also be molded from wax or synthetic plastic material, or from other suitable materials.

After the extension member 23 is attached to the die blank 10, the compound 14 is inserted into the aperture 11 of the extension member 23 and into one extruded aperture gourd 11 of the die material, as shown in FIG. partially pushed into. However, in this case, the flow TfrJJ compound 14 at any location
The extent to which the die material protrudes into the aperture of the piece of die material 10 is reduced by an amount equal to the thickness of the extension member 23 at that portion. Since the thickness of the extension member 23 increases toward the outer periphery of the die material piece, the rate of reduction in the extent to which the compound penetrates into the die material piece 10 increases closer to the outer periphery.

When it is detected by the aforementioned glove that the compound 14 has reached the desired position, an electrolytic or chemical corrosion method,
or by any other suitable method described in the aforementioned European Patent Application to remove surface material from the inner surface of the die aperture 11. In order to protect the surface 19 of the die material piece from corrosive effects during corrosion, the extension member 23 can be held in contact with this surface 19.

After the surface material has been removed from the inside surface of the extrusion aperture, the extension piece 23 can be removed as shown in FIG. 9 and the piece of die material can be used as is.

During the die forming process, the effect of the method of attaching the profile extension member 23 to the die material piece is that, in addition to the variation of the axial abutment depth given by the basic method, the extrusion pressure variation in the cross section of the die material piece is Another one that depends only on
The two contact depth variations are cumulative.

In any of the foregoing methods, the axial abutment length in each section of the extrusion aperture is more closely related to the resistance to flow and the extrusion king in that section, so that it is approximately uniform over the entire cross-section of the extrusion aperture. You will get a die that can create a strong flow.

A suitable material for use with the flowable compound in the method according to the invention would be the acid-resistant paste commercially available under the trade name Sericol 922.
After the paste is partially pushed into the die, the die is fired to solidify the paste. The outside of the die is then coated with lacquer and the die is then etched in aqua regia to remove the steel of the piece of die material from the aperture areas not contacted by the acid-resistant paste. Next, Sericol 922 is removed with a sodium hydroxide solution.

This solution also uses K to strip the lacquer from the die.

Sericol 922 to increase the viscosity of the paste
Silica powder (for example, commercially available under the trade name Aerosil) can be added to the solution.

Flowable materials that can be used as a substitute for the flowable materials described above are resins of the type that are cured by exposure to ultraviolet light, such as those sold under the trademark UOB Resin T. Reaction-curing resins may also be used. Other materials suitable for use as flowable compounds are those commonly used to stimulate aluminum flow bars when testing extrusion dies. . This material includes material sold under the trademark Philia Wax with the addition of 5% paraffin wax. This material has the advantage of being cold-usable, easy to handle, and easily peeled off from the die after corrosion.

[Brief explanation of drawings]

FIG. 1 is an end view of an extrusion die, FIG. 2 is a vertical cross-sectional view of the die of FIG. FIG. 6 is a vertical cross-sectional view of a die modified according to an embodiment of the present invention, and FIGS. 7 to 9 are vertical cross-sectional views showing various stages of another die forming method according to the present invention. DESCRIPTION OF SYMBOLS 10... Dice material piece, 11... Extrusion aperture, 12... Avachea cylindrical part, 13... Apachea arm part, 14... Fluid compound, 16... Profile, 20... Circular recess, 21...bottom, 23.
・Extension member. shiji[1Jcf)il'1) (i'J'M ni change u4su, L) ゐ・2・h・3. F5.4・FJ35 procedure supplement i, 'E t''% < ij formula) l (1 Japanese C30 (F, July 2-11 Patent Office Commissioner Uga Michibe 1, Indication of the case 1985 Patent application No. 57648 2, Title of the invention: Method for forming an extrusion die 3, Who makes the amendment, what the case is, Patent applicant Hobson, [Dlxs, Limi 7-Tsudo 4, Agent]
Person (Postal code 310 (1) June 1980
10 [1 (Shipping 1 1985 6' Ji 25 It) 6,
Supplement 1 [Subject of

Claims (1)

[Claims] 1. Forming an extrusion aperture in a die piece of material; and forcing the flowable material at least partially through the extrusion aperture such that the leading end surface of the material is deformed in the extrusion direction. , and then reshaping the piece of die material such that the axial abutment depth of the extrusion aperture at any location along the outer circumference of the extrusion aperture corresponds to the deformation of the distal surface of the flowable material at this location. A method of forming an extrusion die comprising the additional step of adjusting the axial abutment depth at each section along the outer circumference of the extrusion aperture by an amount that depends on the distance of said section from the center of the piece of die material. Characteristic method for forming extrusion dies. 2. Said adjustment of the axial abutment depth is effected by profiling the inlet end face of the die material piece so as to reduce the axial thickness of the die material piece by an increase proportional to its distance from its center. A forming method according to claim 1. 3. A forming method according to claim 2, wherein the inlet end face of the die material piece is profiled by machining. 4. According to any one of claims 1 to 3, the additional step of adjusting the axial depth is carried out before the reshaping of the die material piece corresponding to the deformation of the flowable material. How to form. 5. prior to forcing the flowable material at least partially into the extrusion aperture, by attaching an extension member across the inlet end face of the piece of die material having an aperture aligned with the extrusion aperture of the piece of die material; Adjustment of the axial abutment depth is carried out, and the extension member has an axial thickness that increases in proportion to the distance from the center of the die, so that the flowable substance is able to control the extrusion of the extension member and die piece of material. the axial depth into which the flowable material plunges into the piece of die material in any part is reduced by the axial thickness of the extension member in that part, and then A method according to claim 1, wherein the extension member is removed from the die material piece before the die material member is used in an extrusion process. 6. A method according to claim 5, wherein the extension member is a preform attached to the piece of die material or a part cast in situ on the piece of die material. 7. The method according to claim 6, wherein the extension member is made of wax or synthetic plastic material. 8. The die material piece is reshaped by a chemical or electrolytic corrosion method, and the extension member is left in contact with the die material piece so as to protect the inner end surface of the die material piece during the corrosion process. A forming method according to any one of FIGS. 5 to 7. 9. The forming method according to any one of claims 1 to 8, wherein the axial contact depth is adjusted linearly from the center of the die to the outer periphery. 10. The forming method according to claim 9, wherein the ratio of the degree of decrease in the axial contact length to the distance from the center of the die is within the range of 1:18 to 1:12.