JPH05261428A - Extrusion molding method and apparatus therefor - Google Patents

Abstract

PURPOSE: To avoid the material damage caused on the inner surface of the inside bush of a receiving vessel applied with mechanical large load by the tension and the compressive stress at the extrusion molding time. CONSTITUTION: In thus extrusion molding method having the receiving vessel 1, the receiving vessel is composed of the inside bush 3 having a hole 2 in the vertical range provided with plural wall portions 4, 5, i.e., a heating or a cooling device 32, at least one of intermediate portion 4 provided with a heating or a cooling device 42, 52, and at least one of outside portion 5. A material heated to a forming temp. in the inside bush is extruded from the inside bush and further, from a female die at the end surface, and at this time, the receiving vessel receives mechanically the load with the extrusion forming cycle, but since plural wall portions are mutually combined and the temp gradient of the receiving vessel is set or adjusted, the increase of the tension stress is prevented and the occurrence of damage is avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The invention comprises a heating or cooling device in which the receptacle is formed from a plurality of wall parts, possibly from several parts, which are preferably connected to each other by a shrink fit. An inner bush having a particularly non-circular hole in the longitudinal extent and at least one outer part arranged approximately concentrically around the inner bush, with a heating or cooling device, and possibly An extrusion, which comprises at least one intermediate part, preferably an intermediate bush, which is preferably equipped with a heating or cooling device, and which is heated to an extrusion temperature of 450 to 750 ° C., preferably 500 to 600 ° C. in the inner bush. A molding material, for example aluminum, is extruded by the extrusion piston from the inner bushing at the end face out of the forming die, the receiver mechanically in the extrusion cycle. Multiplied by the weight, to an extrusion molding method, especially with the receptacle comprising a hot-work steel. Furthermore,
SUMMARY OF THE INVENTION The present invention is directed to a longitudinal direction, in which the receiver, which is optionally coated with a heat insulating material, is provided with a heating or cooling device, which is formed by a plurality of wall parts, i.e. optionally a plurality of parts. An inner bush which extends through the inner bush, in particular with a non-circular, eg elongated or oblong hole, and arranged approximately concentrically around this inner bush
These wall parts include at least one outer part provided with a heating or cooling device and, optionally, at least one intermediate part with possibly heating or cooling device, for example an intermediate bush. Are joined together, preferably by shrink fit, to each other.
Apparatus for carrying out the method according to one of the preceding claims, for extruding, preferably consisting of hot-worked steel, with a receiver.

[0002]

2. Description of the Related Art In known devices, the short side of the inner bush is
Should withstand tensile and compressive stresses in these ranges,
Attempts have been made to place inserts of various materials. However, it has been found that this approach serves no purpose with regard to the expensive construction of the receiver and, nevertheless, the material wear in these areas.

[0003]

The object of the present invention is, in particular, the inner surface of the inner bush of a receiver of this kind, which can be maximally mechanically loaded during extrusion by the tensile and compressive stresses that occur. It is to avoid material damage that occurs in the area of the short side.

[0004]

According to the method of the present invention,
The task is to reduce the tensile stresses that occur in the region of the area close to the surface of the holes in the inner bush that are elongated in the material at higher temperatures during the extrusion process during operation or in the straight short side or rounded short side. In order to minimize, the compressive or contractive stresses present or formed during the extrusion cycle are adjusted in at least one of the wall parts surrounding the inner bush, preferably in the whole wall, these wall parts Or a temperature gradient is set over the wall by means of a heating or cooling device, for example formed by a reduction of the heating power in the wall range, whereby there is an area close to the inner surface of the hole in the inner bush, or a straight short side or roundness The compressive stress is set on the short side, and the value of this compressive stress is less than or equal to the compressive yield stress of 0.02% of the material at the working temperature and this value or this compressive stress during the extrusion cycle during continuous operation. so Held at or about adjusted to the same height by adjusting the degree gradient, thereby compensating for the creep or relaxation of the material and increasing the tensile stress above the crack initiation stress during the extrusion cycle It is solved by preventing. Furthermore, with the device according to the invention, this problem is superimposed on the temperature gradients that occur over the individual wall parts or the entire wall of the receiver and, if applicable, on the case of the individual wall parts or the entire wall. To detect the formation of mechanical stresses, at least one temperature-measuring device is arranged in the inner and outer areas of the wall or of the individual wall parts, each having an effect on the inner wall part or the inner bush. , Thermal insulation to the surroundings of individual wall parts or all wall parts or receivers or to heating or cooling devices, depending on the determined measured values or in relation to these measured values, possibly via control devices Alternatively, the effect of heat flow is solved by being adjustable to set a predetermined temperature gradient that drops to the outside.

By the increase of the temperature gradient carried out according to the invention, which is simply achieved by slight heating of the outer wall area of the receiver or by increased cooling or reduced insulation of the outer wall area insulation. The stress acting on the material region on the short side of the inner bush is set to a height that prevents crack formation in these regions.

According to the invention, the temperature gradient is arbitrarily or precisely superposed on the temperature gradient normally present or occurring in a receiver of this kind or, if no temperature gradient is present, is set appropriately and Thus, the object of the invention, namely a smaller material load on the short side of the inner bush, can be achieved and in some cases the heating power can be saved. The addition of known devices for achieving the construction of the invention is simple. This is because the mounting of the temperature measuring device and the control device for adjusting the heating or cooling of this kind of receiver is possible simply and easily afterwards.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail with reference to the drawings.

The receiver 1 comprises a preferably one-piece inner bush 3 which is preferably cylindrical and has a hole 2 which is not circular in cross section and which extends longitudinally through the receiver 1. The inner bush 3 is surrounded by a cylindrical intermediate bush 4, which is surrounded by a cylindrical outer portion 5. Wall part 4 as this middle bush
Can be shrunk onto the inner bush 3. The wall portion 5 may be shrink fitted onto the wall portion 4.

The receiver 1 is heated by a heating device for extrusion molding. Additional cooling devices can also be provided to set the temperature or to cool the receiver 1. A heating or cooling device is shown at 32 in the inner bush 3. A heating or cooling device of this kind is indicated at 42 in the intermediate bush 4 and at 52 in the outer part 5. This outer part has several insulating layers 11, 12, 1
Surrounded by 3, these insulating layers are made removable so that the heat dissipation can be adjusted.

Extrusion is carried out at higher temperatures. When extruding aluminum, the inner bush 3 is heated to a temperature of 500 to 600 ° C., for example.

A wall portion 4 arranged around the inner bush 3.
And 5 are used to absorb the pressure exerted in the bore 2 by the extrusion piston acting on the material. The dimensions and the heat-shrinking force against which the shrinking wall sections 4 and 5 act on the inner bush 3 or the holes 2 at the operating temperature are selected in a suitable manner.

During operation or during extrusion, however, a considerable force D is created on the longitudinal side 34 of the hole 2 and is exerted on the material of the inner bush 3 by this relatively large extension.
Causes a considerable tensile stress Z in the material in the region 10 of the short side of the inner bush 3. Crack formation, in particular by cracking due to the tensile stress Z occurring in this range 10 during the load alternation process or during extrusion and subsequently by the compressive stress D _N exerted in this range 10 by the wall sections 4 and 5 Creep or wear of the material or damage to the material due to the alternating stresses that cause

If an additional temperature gradient ΔT is formed across the wall parts 4 and 5 according to the invention, the compression force value D _N is increased by the value D _T by increasing the shrinkage of these wall parts 4 and 5. It is possible to counteract the resulting tensile stress Z. Therefore, a compressive stress whose value is less than or equal to the compressive yield stress of 0.02% of the material at the working temperature is set in the area close to the inner surface of the straight short side or the rounded short side of the hole of the inner bush. This value is kept at about the same height or adjusted or readjusted at the same height by adjusting the temperature gradient during the extrusion cycle during continuous operation, whereby the creep or relaxation of the material is compensated and the extrusion is performed. The tensile stress is prevented from exceeding the crack initiation stress in the cycle. It is therefore to be noted that the sum of the compressive stresses D _N and D _T occurring in the range 10 during operation during temperature rise and without the pressure Z exerted by the material to be extruded (ie at the hot inner bush 3). (Before and after extrusion)
The compressive yield stress of the material in range 10 should not be exceeded. This is because in this case the material is squeezed out into the holes 2 in the area 10 and this material is worn out and the wear of the inner bush 3 is accelerated. The compressive or contractive stresses that occur when a temperature gradient is formed in the wall of the receiver at the short side of the hole during the extrusion cycle due to the compressive yield of the material at processing temperatures in the region of the area close to the inner surface. If the limit of 0.02% of the stress is not exceeded or due to the temperature gradient established in the wall of the receiver, the compressive or contractive stress is between 1 and 30 at the working temperature on the short side of the inner bush during the extrusion cycle. %, Preferably 2
To 20%, especially 4 to 10% up to 0.0 of material
It is advantageous if it is adjusted below a compressive yield stress of 2%.

At 6, holes are shown in the walls 4 and 5, to which temperature measuring devices 7 can be introduced, which are connected to a control device 8. By means of these temperature measuring devices 7, the temperature of the inner area or the inner surface 33 of the wall part 4 and the temperature of the outer area or the outer surface 9 of the wall part 5 are measured and supplied to the control device 8, which controls the temperature gradient. Detecting ΔT and adjusting the heating or cooling device 42, 52 in the wall parts 4 and 5 and possibly in the inner bush 3. The hole 6 and the temperature measuring device 7 may be provided at a plurality of places of the receiver 1.

Further, it should be noted that the predetermined temperature gradient ΔT is not exceeded even while the inner bush 3 is being heated.
Otherwise, the compressive stresses D _N and D _T exerted by the wall portions 4 and 5 on the area 10 of the inner bush 3
Is greater than the compressive yield stress in this range, and thus creep or flow of the material damages this range.

The temperature gradient ΔT of the receiver wall, which is to be set according to the invention, is the normal temperature gradient produced by the insulation of the material of the wall parts 4 and 5 of the receiver and heating device during operation in conventional equipment. Is accurately superimposed on. Therefore, in the method or receiver of the present invention, a temperature gradient higher than the conventional temperature gradient is set. This increase in temperature gradient is 5 to 50 ° C, preferably 10 to 40 ° C, especially 25 to 3 ° C.
It is in the range of 5 ° C.

In order to reduce or avoid material stress, especially in the region 10 of the short side of the hole 2, this temperature gradient is already applied after a small number of extrusion cycles, in particular after 20 extrusion cycles. It has been found to be preferable to superimpose on the temperature gradients that occur in the normal or respective apparatus or receiver, or the temperature gradients after about 20 extrusion cycles or after an enhanced initial relaxation of the material or at the initial stage. It should be set or reset after a creep and held for further operation.

Increase of temperature gradient ΔT, that is, 1 of outer wall temperature
The decrease in ° C increased the compressive stress exerted by the walls 4 or 5 on this region by 4 N / mm ^{2 in} the region 10 of the short side. Worked steel, eg DIN material number 1.234
A compressive yield stress of 3 should not be exceeded, which is approximately 900 N / mm ² at 500 ° C. or approximately 600 N / mm ² at 600 ° C.
According to the invention, the setting or resetting of the temperature gradient during operation allows the walls or individual wall parts to provide a non-circular hole side extent at right angles to the plane defined by the hole longitudinal sides. The compressive stresses exerted on the material during the extrusion cycle are based on normal operating conditions or those which have been reduced by relaxation or operating conditions which are normal or existing in conventional equipment or are based on elevated temperature gradients. About 50 to 150 N / m
It is designed to be increased by m ² , preferably 100 to 130 N / mm ² .

In the method according to the invention, for example 290N
The compressive stress D _N in the range 10 reduced by the tensile stress Z reduced to a value of / mm ² is increased by 4 × 30 N / mm ^{2 at} a temperature gradient ΔT of 30 ° C. to 410 N / mm ² , for example.
It can be a value of mm ² . This value is sufficient to avoid fatigue cracking in the range 10 and small enough not to exceed the compressive yield stress in the range 10.

With the method according to the invention and the setting of an additional temperature gradient of ΔT = 22 ° C., the expected life of approximately 50000 extrusion cycles is today, without cracking in the area 10 of the inner bush 3, It is already known that it has been able to be more than doubled.

The formation of the temperature gradient ΔT should take place before the material exhibits a fatigue phenomenon and, in particular, when the material of the inner bush 3 has reached half the creep limit. This depends on the extrusion temperature and the compressive stress D'caused inside the inner bush 3, but must be within a time not exceeding 20 to 150 extrusion cycles.

In the receiver 1 with multi-layered thermal insulation 11, 12, 13 the removal of a part of this thermal insulation results in a temperature gradient in the receiver wall at a constant temperature of the inner surface of the inner bush. Only values of 5 to 50 ° C, especially about 30
It is preferred if it can be increased by ° C.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a receiver for extrusion molding.

[Explanation of symbols]

 1 Receiver 4,5 Wall part 7 Temperature measuring device 8 Control device ΔT Temperature gradient

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[Procedure amendment]

[Submission date] February 4, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

Claims (11)

[Claims] 1. An inner bush having longitudinal holes, wherein the receiver comprises a plurality of wall sections, ie heating or cooling devices,
Included in this inner bush is at least one outer part with heating or cooling devices and at least one intermediate part, which are arranged substantially concentrically around the inner bush, at a temperature of 450 to 750 ° C. in the inner bush. Extrusion with a receiver, in which the extrusion material heated to the extrusion temperature is extruded by the extrusion piston from the inner bush and at the end face out of the forming die and the receiver is mechanically loaded in the extrusion cycle. In the forming process, in order to minimize the tensile stress that occurs in the region near the surface or the short side of the hole of the inner bush which extends into the material at a higher temperature during the extrusion process during operation, the extrusion stress is minimized. The compressive or contractive stresses present or formed during the molding cycle are
At least one of the wall parts surrounding the inner bush is regulated and a temperature gradient is established on these wall parts or on the whole wall by means of heating or cooling devices, whereby an area close to the inner surface of the holes of the inner bush or The compressive stress is set on the short side, and the value of this compressive stress is less than or equal to the compressive yield stress of 0.02% of the material at the working temperature and this value or this compressive stress during the extrusion cycle during continuous operation. Is maintained at or about the same height by adjusting the temperature gradient at, thereby compensating for the creep or relaxation of the material and the tensile stress above the crack initiation stress during the extrusion cycle. An extrusion molding method characterized in that rising is prevented. 2. The predetermined temperature gradient is superimposed on a normal temperature gradient which occurs during operation and is obtained by insulation, thermal conductivity of the wall material, heating, etc. or which occurs by itself. The method described in. 3. The compressive or contractive stresses that occur when a temperature gradient is formed in the wall of the receiver in the area close to the surface of the holes or at the short sides of the material during the extrusion cycle, in areas close to the inner surface. Method according to claim 1 or 2, characterized in that the limit of 0.02% within the compressive yield response of the material at processing temperatures in the range is not exceeded. 4. A material having a compressive or contractive stress due to a temperature gradient established in the wall of the receiver during the extrusion cycle in the area close to the surface of the inner bush or in the short side up to 1 to 30% at the processing temperature. 4. The method according to claim 1, wherein the method is adjusted to a compressive yield stress of 0.02% or less. 5. The method according to claim 1, wherein a temperature gradient in the receiver wall of 5 to 50 ° C. is set. 6. A temperature gradient is set or reset after about 20 extrusion cycles or after an intensified initial relaxation of the material or after an initial creep and held for further operation. The method according to any one of claims 1 to 5, wherein 7. A method as claimed in claim 1, characterized in that a predetermined temperature gradient is not exceeded when the receiver is heated to the operating temperature. 8. By the setting or resetting of the temperature gradient during operation, the extrusion of the extrusion cycle by the wall or individual wall parts in the lateral extent of the hole at right angles to the plane defined by the longitudinal sides of the hole. The compressive stress exerted on the material during the operation is about 5% lower than that under normal operating conditions or reduced stress due to relaxation or in conventional equipment under normal or existing temperature gradient-based operating conditions.
Method according to one of the claims 1 to 7, characterized in that it is increased by 0 to 150 N / mm ² . 9. An inner bush having a plurality of wall portions, ie, a heating or cooling device, having an aperture extending longitudinally through the inner bush, and substantially concentric around the inner bush. 9. At least one outer part, which is provided with a heating or cooling device, and at least one intermediate part, these wall parts being connected to one another, In a device with a receiver for extruding to carry out the method according to one, the temperature gradient (ΔT) that occurs over the individual wall parts or the entire wall of the receiver (1) and , At least one temperature-measuring device (7), acting on the inner wall part or the inner bush, respectively, for detecting the formation of mechanical stresses on the individual wall parts (4,5) or on the entire wall Wall or individual Surrounding the individual wall parts or all wall parts or receivers (1), which are arranged in the inner and outer extents of the wall parts (4,5) and by the measured values obtained or in relation to these measured values. Or heating or cooling device (4
2, 52) A device with a receiver for extrusion, characterized in that the action of heat insulation or heat flow can be adjusted to set a predetermined temperature gradient (ΔT) which decreases to the outside. 10. A temperature gradient (ΔT) between the inner surface (33) of the wall portion (4) surrounding the inner bush (3) and the outer surface (9) of the outermost wall portion (5) is detected or measured. The device according to claim 9, characterized in that 11. The receiver (1) is a thermal insulator (11,1).
2, 13) and is characterized in that the temperature gradient in the receiver wall can be increased at the constant temperature of the inner surface of the inner bush by removing part of this thermal insulation, The device according to claim 9 or 10.