JPH10166038A - Extruding device for variable section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the extruding device for variable section capable of stably performing the extrusion for variable section with excellent precision. SOLUTION: The extruding device is provided with a container in which a stock to be formed is stored, a press which is arranged on one end side of the container and presses the stock in the container toward the other end side, a die assembly 5 which is arranged on the other end side of the container and forms the stock into the product shape through an extrusion hole, a die stack 6 to support the die assembly on a block, and a driving means to change the shape of the extrusion hole. The die assembly is provided with a fixed die 11 in which a fixed die hole is made, and a movable die 12 which is movably provided on the fixed die and in which a movable die hole is made, a tip of a driving part 24 of the driving means is connected to the movable die 12, and an opening part in which the driving part can be inserted is formed in the fixed die and the die stack, and a displacement measuring means in which the tip part is engaged with the movable die 12 and its movement is measured, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable cross-section extrusion molding apparatus for extruding a molded body whose cross-sectional shape changes in the extrusion direction.

[0002]

2. Description of the Related Art As is well known, various pipes such as fin tubes for heat exchangers and various structural members used in vehicles for which weight reduction is strongly required are formed by extrusion of aluminum or aluminum alloy. Is often used. In this extrusion molding, a die having an extruded hole having a cross-sectional shape such as the above-described constituent member is fixed to a tip portion of a container, and a heated material (a billet) is placed in the container.
And insert the billet into the press (stem)
By pressing to the die side and extruding from the extrusion hole, the constituent member is formed. According to such an extrusion process, since the extrusion hole of the die has a constant cross-sectional shape, the obtained component member or the like is also formed into a constant cross-sectional shape in the longitudinal direction.

However, among the structural members described above, for example, in the structural members of various vehicles such as general passenger cars and trucks, when these are formed by the extrusion dies, for example, the obtained side frames are oriented in the longitudinal direction. In order to have a constant cross-sectional shape, in other words, a constant second moment of area, a member having a dimension and strength more than necessary in the longitudinal direction is formed, and the molding material is wasted and uneconomical. In addition, there is a problem in that the installation space of the constituent member is prevented from being reduced in size and weight.

[0004]

A conventional extrusion die for solving such problems is disclosed in Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent No. 31527, the extrusion die is composed of a fixed die that is fixed to a container, and a movable die that is movably provided with respect to the fixed die, and by appropriately moving the movable die, By changing the shape of the extrusion hole formed by the communicating part between the fixed die hole of the fixed die and the moving die hole of the moving die, and changing the cross-sectional shape of the component to be formed in the longitudinal direction, for variable cross-section extrusion Dice have been proposed. According to such a variable cross-section extrusion die, extrusion molding in a shape corresponding to the generated stress distribution is possible, so that the stress is constant at any part, for example, at the center or both ends in the longitudinal direction. There is an advantage that a component or the like having a reasonable rational cross-sectional shape can be formed.

However, when trying to incorporate the above-mentioned conventional die for variable-section extrusion into an extrusion molding apparatus, if the stationary die and the movable die are to be moved relative to each other, both of the fixed die and the movable die are moved in the direction of extrusion by the press. It is difficult to maintain the extrusion reference center of the molded body extruded from the above, and thus it is difficult to perform stable extrusion, and the apparatus is complicated. Due to the application of a load in the direction, it is extremely difficult in terms of structure to accurately and smoothly slide the moving die with respect to the fixed die while securely holding the relative position between the press and the fixed die. In addition, there are various practical problems that it is extremely difficult to extrude with high precision. The present invention has been made to effectively solve the problem that occurs when such a variable cross-section extrusion is actually performed, and a variable cross-section extrusion that can stably perform a highly accurate variable cross-section extrusion. It is intended to provide a device.

[0006]

According to a first aspect of the present invention, there is provided a variable section extrusion molding apparatus according to the present invention, comprising: a container for accommodating a molding material; A die incorporating a pressing machine for pressing the molding material toward the other end and a die disposed at the other end of the container and for molding the molding material extruded from the container into a product shape through an extrusion hole. An assembly, a die stack for supporting the die assembly on a base, and a driving means for changing the shape of the extrusion hole, wherein the die assembly is fixed to the die stack, and a fixed die hole is formed. And a movable die provided movably in the stationary die and having a movable die hole formed therein. The movable die is formed by a communicating portion between the stationary die hole and the movable die hole. The movable extrusion die is connected to the tip of the driving unit of the driving means, and the die assembly and the die stack have openings through which the moving die or the driving unit can be inserted. And a displacement measuring means for measuring the movement of the movable die, the distal end being engaged with the movable die while being inserted into the opening. .

According to a second aspect of the present invention, a hole communicating with the fixed die hole is formed in the fixed die,
The movable die is slidably incorporated in the hole, and the invention according to claim 3 is a die stack that supports the press machine, the container, and the die assembly. , Are sequentially arranged in the horizontal direction, the opening is formed in the fixed die and the side wall of the die stack, and the driving means is fixed to the side wall of the die stack. .

Further, according to a fourth aspect of the present invention, there is provided a displacement measuring means according to any one of the first to third aspects, wherein the rod is inserted through the opening so that a tip end abuts the movable die. It is characterized by comprising a biasing member for biasing a rod toward the moving die side, and a displacement measuring device connected to a base end of the rod and converting a displacement of the rod into an electric signal. Is what you do.

The invention described in claim 5 is the first invention.
A heating means for heating the die assembly is provided in the die assembly according to any one of claims 1 to 4, wherein the die assembly has a tubular shape. In the die ring, the fixed dies are sequentially arranged in the extrusion direction of the molding material, and the back plate that supports the fixed dies is housed.
By opening an opening through which the movable die or the driving unit can be inserted in communication with the opening of the fixed die, and by incorporating a plurality of heaters along the circumferential direction on the outer periphery of the die ring. It is characterized in that the above-mentioned heating means is constituted.

In the invention according to any one of the first to sixth aspects, a die assembly having a fixed die and a moving die is supported on a base via a die stack, and formed into a die assembly and a die stack. Since the movable die is driven by inserting the movable die or the drive unit connected to each other into the opening, and the movement of the movable die is measured by displacement measuring means engaging with the movable die, Based on the position of the fixed die, the movable die can be moved accurately and smoothly with respect to the fixed die, so that high-precision variable section extrusion can be stably performed. Also,
Since the extruded molded body extends on the basis of the fixed die hole, the guide is facilitated.

In the invention according to claim 2, a hole is formed in the fixed die, and the movable die is slidably incorporated in the hole. It is possible to smoothly move the moving die without causing relative displacement of the moving dies. In addition, claim 3
In the invention described in the above, since the opening is formed in the side wall of the fixed die and the die stack, and the driving means is fixed to the side wall of the die stack, the relative displacement of the fixed die, the moving die and the driving means is reduced. Since the pressing axis of the driving means can be kept constant at all times, there is no danger that the driving force of the moving dice increases due to the displacement of the pressing axis, and the sliding of the moving dice with respect to the fixed dice does not occur. The movement can be performed accurately and smoothly.

Further, when measuring the displacement of the movable die in order to control the movement of the movable die, for example, it is conceivable to measure the displacement of the driving section of the driving means.
Since it is inevitable that a play (gap) occurs between the driving unit and the moving die, even if the displacement amount of the driving unit is measured, the play amount is caused by the play between the moving unit and the moving die itself. Error occurs. In this regard, according to the invention described in claim 4, since the tip of the rod urged toward the moving die by the urging member is directly brought into contact with the moving die, the displacement amount of the moving die itself is accurately measured. As a result, the movement of the moving die can be controlled with high accuracy.

In such an extruder, the die assembly is heated by the heat from the container into which the heated molding material has been charged at the beginning of the extrusion molding. With the passage of time, heat escapes from the die assembly side to the die stack side, and the temperature of the die assembly gradually decreases, and the die assembly thermally contracts,
Conversely, the die stack thermally expands. For this reason, a gap may be formed between the die stack and the die stack that supports the die assembly, and the position of the fixed die may be unstable. Therefore, if the heating means for heating the die assembly is provided as in the invention according to claim 5, when the temperature of the die assembly shows a tendency to decrease with time, the die is positively driven by the heating means. By heating the assembly, it is possible to prevent the occurrence of a gap between the assembly and the die stack due to thermal shrinkage.

In this type of extrusion apparatus, a large load acts on the die assembly in the extrusion direction due to a pressing force from a press at the time of extrusion molding. Therefore, when the die assembly is composed of only the fixed die and the movable die, it is necessary to increase the thickness of the fixed die in order to resist the shearing force caused by the load. On the other hand, since high precision of several tens to several hundreds of microns is required for processing of the fixed die hole of the fixed die, when the thickness dimension of the fixed die becomes large, the processing is troublesome and the manufacturing unit price is reduced. Invite soaring.

In this regard, according to the invention described in claim 6,
Since the die assembly has a configuration in which a back plate for supporting the fixed dies and the fixed dies are housed in a tubular die ring, the thickness of the fixed dies can be set to be thinner, and the production thereof can be performed. As well as the ease of the die ring and the back plate, for various fixed dies corresponding to different shapes,
It is economical because it can be used as a common member. In this case, in order to drive the moving die from the outside, it is necessary to form an opening through which the moving die or the driving unit can be inserted in the outer peripheral portion of the die ring in communication with the opening of the fixed die. Good.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 8 show an embodiment of a variable section extrusion molding apparatus according to the present invention. FIG.
As shown in FIG. 1, this variable section extrusion molding apparatus includes a container 2 in which a billet (molded material) 1 of aluminum or an aluminum alloy is stored, and a billet 1 in the container 2 which is disposed at one end of the container 2. (Pressing machine) 3 which presses the container 2 toward the other end, and an extrusion hole 4 which is provided at the other end of the container 2 and which extrudes the molded material from the container 2.
A die assembly 5 formed into a product shape through
A die stack 6 for supporting the die assembly 5 on a base, and an end platen 7 disposed at a stage subsequent to the die stack 6 are disposed in a horizontal direction.
And a displacement measuring means 40 for directly measuring the displacement of the moving die 12 of the die assembly 5 is provided. Here, the stem 3, the die stack 6, and the end platen 7 are fixed directly or indirectly on the floor (base), respectively, and the stem 3 and the end platen 7
They are connected by tie rods (not shown) interposed at the corners.

The die stack 6 is shown in FIGS.
As shown in FIG. 5, a U-shaped concave portion 9 is formed at the center of the rectangular plate-shaped member and opens upward. And
The die assembly 5 is housed in the recess 9 so that it can be inserted and removed. The die assembly 5 is for extruding, for example, an H-shaped member in which a part of the flange is not formed. A movable die 12 slidably provided in a hole 22 formed in the fixed die 11, a back plate 13 for supporting the fixed die 11, and a back plate 13 provided on the upstream side of the fixed die 11 together with the back plate 13. The lead-in plate 16 sandwiching the fixed die is housed therein. Here, a groove 9a is formed in the inner wall of the concave portion 9 of the die stack 6 in a direction intersecting with the extrusion direction of the molding material.
The protrusion 10a formed on the outer periphery of the die ring 10 is fitted therein.

On the other hand, the fixed die 11 is a substantially disk-shaped member made of hot work tool steel, and is shown in FIGS.
As shown in the figure, a concave portion 17 serving as a flow path for the molded material 1 extruded from the container 2 is formed at the center of the upper surface 15 located on the container 2 side, and a fixed die hole is formed at the bottom of the concave portion 17. 18 are drilled.

The fixing die hole 18 has a flange portion forming hole 19 having the same width dimension as the maximum thickness of one flange of the H-shaped member to be formed, and the flange portion forming hole 1
9, a web forming hole 20 extending in a direction orthogonal to the central portion.
And a flange communication hole 21 formed at the other end of the web forming hole 20. The flange portion communication hole 21 has the same length as the flange portion formation hole 19 and is formed so as to have a larger width dimension than the flange portion formation hole 19. A hole 22 extending in parallel with the web forming hole 20 and penetrating between the side surfaces and communicating with the fixed die hole 18 is formed in the center of the side surface of the fixed die 11. A guide wall 23 for guiding the side surface of the movable die 12 slidably and densely is formed at a central portion of the side surface of the movable die 12. The movable die 12 is slidably provided in the hole 22 of the fixed die 11.

As shown in FIG. 7, the moving die 12 has a head 25 inserted into the hole 22 and a head 25.
Is integrally formed with a clamp portion 26 to which a distal end portion 24a of a drive shaft (drive portion) 24 of the drive device 8 for sliding the inside of the hole portion 22 is connected. The head 25 is a substantially rectangular plate-shaped member made of hot tool steel or the like, and has a flange portion forming hole 27 formed at the center thereof having the same size as the fixed die hole 18, Web forming hole 28 orthogonal to the central portion of portion forming hole 27
And a moving die hole 30 formed of a flange communication hole 29 formed at the other end of the web forming hole. The web forming hole 28 is provided in the moving die 1.
It is formed so as to be parallel to the second side wall 31. The moving die 12 fixes the flange portion forming hole 27 to the fixed die hole 1.
8 is located on the side of the flange communication hole 21 and communicates with the web forming holes 20 and 28, and is slidably inserted along the guide wall 23 in the hole 22 of the fixed die 11.

An opening 34 slightly larger than the hole 22 of the fixed die 11 is formed in the side wall of the die ring 10 looking in the moving direction of the moving die 12. 12 is mounted in the hole 22 of the fixed die 11 incorporated therein. Further, a plurality of (in the figure, a total of 12) long holes 10c are formed in the outer peripheral portion of the die ring 10 except for the portion where the opening 34 is formed.
A heater (heating means) 50 is incorporated in Oc. On the other hand, as shown in FIG. 2, the driving device 8 is fixed to a side surface of the die stack 6 via a mounting member 32. The driving device 8 includes a hydraulic cylinder 33 and a driving shaft 24 that moves forward and backward by the hydraulic cylinder 33. The driving device 24 includes an opening formed in a side wall of the die stack 6 and the die ring 10. 34, 35
, And the distal end 24 a thereof is connected to the clamp 26 of the movable die 12.

Further, as shown in FIGS. 1 and 8, the displacement measuring means 40 for directly measuring the displacement of the movable die 12 is attached to the attachment member 32 to which the driving device 8 is attached. I have. This displacement measuring means 40
Is mounted on the mounting table 32 by the bearing 41.
Rod 42 provided to be able to advance and retreat in the moving direction of
And a spring (biasing member) 45 interposed between a bearing plate 41 and a receiving plate 44 fixed to the rod 42 by a pin 43 to bias the rod 42 toward the movable die 42.
And a digital scale (displacement measuring device) connected to the base end of the rod 42 to convert the displacement of the rod into an electric signal
46 and the tip 42 of the rod 42.
a is a moving die 1 which is constantly moved by the urging force of a spring.
2 is brought into contact with the locking plate 12a fixed to the fixing plate 2a. The length of the tip 42a can be adjusted by a screw joint 47.

Next, a method of extruding an H-shaped member made of aluminum or an aluminum alloy using the variable cross-section extrusion molding apparatus having the above configuration will be described with reference to FIGS. First, with the stem 3 retracted,
After the heated aluminum billet 1 is inserted into the container 2, the stem 3 is advanced and the billet 1 is extruded toward the fixed die 11 in the die assembly 5. Then, as shown in FIG. 9, the molding material 1 is extruded from a die hole 4 (a portion indicated by hatching in the figure) formed by a communicating portion between the fixed die hole 18 and the movable die hole 30, and the shape of the die hole 4 is formed. Is extruded. In parallel with this, by appropriately controlling the hydraulic cylinder 33 of the drive device 8, the drive shaft 2
4 and the movable die 12 is fixed to the hole 22 of the fixed die 11.
, The length L of the web between the flanges of the member to be formed can be gradually increased or decreased.

Next, when the moving die 12 is further moved to the position shown in FIG. 10, the flange forming holes 19 and 27 and the flange communicating holes 2 are formed at both ends of the web.
An H-shaped member having a flange having a thickness W corresponding to a portion communicating with 0 and 29 is formed. At this time, by moving the movable die 12 while maintaining the above-described state, the thickness W of the flange can be appropriately changed in the longitudinal direction. Further, as shown in FIG. 11, the web forming holes 20 and 28 of the fixed die hole 18 and the moving die hole 30 are communicated with each other, and one flange portion forming holes 19 and 27 and the other flange portion communicating hole 21 are formed. And 29 are extruded at a position where they do not communicate with each other.
Is extruded only through the extruded holes 4 communicating with the web forming holes 20 and 28. As a result, a flat component having only a flat bar-shaped web corresponding to the length of the extruded holes 4 is formed. Is molded. As described above, the driving device 8
By moving the movable die 12 to an appropriate position with respect to the fixed die 11, components having various variable cross-sectional shapes in the longitudinal direction can be easily formed.

At this time, in order to move the movable die 12 to an accurate position, the displacement of the movable die 12 is measured by the displacement measuring means 40 shown in FIG. That is,
Since the rod 42 is constantly urged by the movable die 12 by the spring 45 and is in contact with the locking plate 12a,
When the moving die 12 moves, it follows the movement, and the displacement amount is directly measured as an output signal from the digital scale 46. Therefore, the hydraulic cylinder 33 of the driving device 8 is controlled in accordance with the displacement amount, and the moving die 12 is moved to a desired position.

At this time, the fixed die 11 has the stem 3
A thrust force generated by pushing out the billet 1 in the container 2 acts on the billet 1,
First, since it acts on the lead-in plate 16 arranged on the upstream side of the fixed die 11, the thrust force directly acting on the fixed die 11 is reduced. Further, as the time elapses, the temperature of the die assembly 5 gradually decreases and the die assembly 5 thermally contracts, and conversely, the die stack 6 thermally expands. Therefore, when the temperature of the die assembly 5 shows a tendency to decrease as the extrusion is performed, the heater 50 is energized to actively heat the die ring 10, whereby the die ring 10 thermally contracts and the die stack 6, and prevents an increase in deformation resistance of aluminum and facilitates variable section extrusion.

When extruding a variable cross section member having another shape by the above variable cross section extrusion molding apparatus,
First, the entire die assembly 5 is lifted by a suspending tool provided on the die ring 10 and pulled out from the recess 9 of the die stack 6, and then the die assembly incorporating the corresponding fixed die and moving die of the member is attached to the die stack 6. What is necessary is just to make it accommodate in the recessed part 9.

As described above, in the variable cross-section extrusion molding apparatus having the above-described configuration, the die assembly 5 having the fixed die 11 and the moving die 12 is supported on the base via the die stack 6 and the fixed die Displacement measuring means for driving the moving dies by inserting the moving dies or the driving units connected to each other into openings formed in the dies and the die stack, and the rods 42 directly contacting the moving dies 12 by the springs 45. Since the movement of the movable die 12 is measured by the reference numeral 40, the position of the fixed die 11 is used as a reference.
The moving die 12 can be moved accurately and smoothly with respect to the above, so that high-precision variable section extrusion can be stably performed. In addition, since the extruded molded body extends based on the fixed die hole 11, the guide becomes easy.

In particular, since a hole 22 is formed in the fixed die 11 and the movable die 12 is slidably incorporated in the hole 22, the relative distance between the fixed die hole 11 and the movable die hole 12 is increased. The displacement of the movable die 12 can be smoothly performed without causing displacement. In addition, since the driving device 8 is fixed to the side wall of the die stack 6, there is no relative displacement between the fixed die 11, the moving die 12, and the driving device 8, so that the pressing axis of the driving device 8 is always constant. Therefore, there is no possibility that the driving force of the movable die 12 increases due to the displacement of the pressing axis. Therefore, sliding of the movable die 12 with respect to the fixed die 11 can be performed accurately and smoothly.

Further, since the displacement of the movable die 12 is directly measured by the displacement measuring means 40, the hydraulic cylinder 33 is controlled based on the electric signal converted by the digital scale (displacement measuring device) 46. The moving die 12 can be moved to a desired position with high accuracy. In addition, the heater 50
The heater 50 is used to positively heat the die ring 10 so that the die stack 6
Can be prevented from occurring due to thermal contraction, and an increase in deformation resistance due to a decrease in the temperature of the aluminum material can be prevented.

The die assembly 5 is placed in a tubular die ring 10 with a back plate 13 and a fixed die 1.
1 and the lead-in plate 16 are housed, so that the thickness of the fixed die 11 can be set to be thinner and its manufacture is facilitated, and the die ring 10, the back plate 13 and the lead-in plate 16 is economical because it can be used as a common member for various fixed dies corresponding to different shapes.

In the above embodiment, only the case where the fixed die 11 and the movable die 12 are formed by extruding H-shaped components has been described. However, the present invention is not limited to this. It is possible to incorporate stationary dies and moving dies for extruding cross-section components.

[0033]

As described above, according to the variable cross-section extrusion molding apparatus according to any one of claims 1 to 6, the position of the fixed die is used as a reference, and the moving die can be accurately positioned with respect to the fixed die. Can be stably performed with high precision variable cross-section extrusion, and the guide is easy because the extruded body extends with reference to the fixed die hole. . At this time,
According to the second aspect of the present invention, there is no relative displacement between the fixed die hole and the moving die hole, and according to the third aspect of the present invention, the fixed die, the moving die and the driving means are not moved. Since there is no relative displacement, the sliding of the movable die with respect to the fixed die can be performed more accurately and smoothly. Further, according to the fourth aspect of the present invention, since the tip of the rod urged toward the moving die by the urging member is directly brought into contact with the moving die, the displacement of the moving die itself is accurately measured. As a result, an effect is obtained that the movement of the moving die can be controlled with high accuracy.

According to the fifth aspect of the present invention, when the temperature of the die assembly shows a tendency to decrease with time, the die assembly is positively heated by the heating means, so that the die assembly can be connected to the die stack. According to the invention as set forth in claim 6, it is possible to prevent both the generation of a gap due to thermal shrinkage therebetween and the increase in deformation resistance due to a decrease in the temperature of the material. The thickness can be set thinner, making it easier to manufacture.
An effect is obtained that various fixed dies corresponding to different shapes can be used as a common member and are economical.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a variable cross-section extrusion molding apparatus of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a longitudinal sectional view showing the die assembly of FIG. 1;

FIG. 4 is a front view of the die ring of FIG. 3;

FIG. 5 is a plan view showing the fixed die of FIG. 1;

FIG. 6 is a sectional view taken along line VI-VI of FIG. 5;

FIG. 7 is a plan view showing the moving die of FIG. 1;

FIG. 8 is a side view showing the displacement measuring means of FIG. 1;

FIG. 9 is a schematic diagram showing a state in which an H-shaped molded material is extruded by an extrusion hole.

FIG. 10 is a schematic diagram showing a state where the moving dice of FIG. 9 are further moved.

11 is a schematic diagram showing a state in which the moving die of FIG. 10 is further moved to extrude an I-shaped molded material.

[Explanation of symbols]

 Reference Signs List 1 billet (molding material) 2 container 3 stem (pressing machine) 4 extrusion hole 5 die assembly 6 die stack 8 driving device (driving means) 10 die ring 11 fixed die 12 moving die 13 back plate 18 fixed die hole 22 hole 23 Guide wall 24 Drive shaft (drive unit) 24a Tip 30 Moving die hole 34, 35 Opening

Claims (6)

[Claims] 1. A container in which a molding material is stored, a press machine disposed at one end of the container and pressing the molding material in the container toward the other end, and a pressurizing machine disposed at the other end of the container. A die assembly into which a die is provided for forming a molded material extruded from the container through an extrusion hole into a product shape, a die stack for supporting the die assembly on a base, and a shape of the extrusion hole The die assembly is fixed to the die stack, and has a fixed die having a fixed die hole formed therein. The fixed die has a movable die hole. A movable die provided, and a communicating portion between the fixed die hole and the movable die hole constitutes the extrusion hole having a variable shape, and the driving die is driven by the movable die. The tip of the drive unit of the step is connected, and the die assembly and the die stack are each formed with an opening through which the moving die or the drive unit can be inserted. A variable section extrusion molding device, wherein a portion is engaged with the moving die and displacement measuring means for measuring the movement of the moving die is provided. 2. The fixed die is provided with a hole communicating with the fixed die hole, and the movable die is slidably incorporated in the hole.
6. The variable cross-section extrusion molding apparatus according to 4. 3. A die stack for supporting the press, the container and the die assembly are sequentially arranged in a horizontal direction, the opening is formed in a side wall of the fixed die and the die stack, and the die is formed. The variable section extrusion molding apparatus according to claim 1 or 2, wherein the driving means is fixed to a side wall of the stack. 4. The displacement measuring means is connected to a rod having a distal end in contact with the moving die, an urging member for urging the rod toward the moving die, and a base end of the rod. And a displacement measuring device for converting the displacement of the rod into an electric signal.
4. The variable cross-section extrusion molding apparatus according to any one of claims 1 to 3. 5. A variable section extrusion molding apparatus according to claim 1, wherein said die assembly is provided with a heating means for heating said die assembly. 6. The die assembly includes a tubular die ring, in which the fixed die and a back plate for supporting the fixed die are sequentially housed in a direction in which the molding material is extruded. In the outer peripheral portion of the ring, an opening portion through which the movable die or the driving portion can be inserted is formed in communication with the opening portion of the fixed die, and a plurality of circumferentially extending along the outer periphery of the die ring. The variable cross-section extrusion molding apparatus according to claim 5, wherein the heating means is configured by incorporating a heater.