JP4449122B2 - Thickness control method of extruded profile - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a wall thickness control method for producing an extruded shape whose shape is stabilized by suppressing dimensional fluctuations of the extruded shape caused by physical or thermal distortion of a die generated during extrusion molding.
[0002]
[Prior art]
A high-temperature billet is pressed from a container toward a die, and an extruded shape member having a predetermined shape is manufactured by passing through a shaping space provided in the die. At this time, the thickness of the extruded profile tends to fluctuate during extrusion molding. Factors that change the wall thickness include die temperature distribution, extrusion force, container sealing force, and the like. For example, when the die is cooled during extrusion by heat dissipation to the outside air, the shaping space is narrowed due to thermal contraction, and the final thickness is reduced compared to the initial stage of the extrusion cycle.
[0003]
On the other hand, the billet is pressed at a predetermined pressure during extrusion molding, but the container sealing force due to the friction between the container inner wall and the peripheral surface of the billet is smaller at the rear end than at the front end of the billet. When the container sealing force is reduced, the force that restrains the die is reduced, so that the center of the die protrudes in the extrusion direction and the die is bent more. As a result, the shaping space is narrowed and the portion of the meat that hits the rear end of the billet The thickness decreases.
Therefore, the present applicant introduced an extrusion die in which a holder for detachably holding a die to a spreader baffle is connected to a spreader baffle in order to suppress wall thickness fluctuation during extrusion molding. In this extrusion die, a part of the load from the spreader baffle is transmitted to the holder, so that the load applied to the die is reduced, and stress concentration and dimensional variation at both ends of the bearing are suppressed. Further, when a heat insulating material is interposed between the die and the holder, the bearing portion is at a constant temperature, so that thermal distortion is reduced, and extrusion molding under stable conditions becomes possible.
[0004]
[Problems to be solved by the invention]
The adoption of the holder greatly reduces the variation in the thickness of the extruded profile due to physical or thermal distortion of the die. However, the force applied to the die is reduced, but still fluctuates, causing an adverse effect on the thickness of the extruded profile. In addition, although the temperature variation of the die can be suppressed by insulating between the die and the holder, the dimension of the die holding portion changes due to the temperature change of the holder, and the force applied to the die varies. As a result, the thickness variation of the extruded profile has not been completely eliminated.
The present invention has been devised to solve such problems, and by making it possible to adjust the force applied to the die through the holder, fluctuations in temperature and container sealing force can be caused by the gap in the shaping space. The object is to produce an extruded profile in which the influence on the die is offset, the force applied to the die is kept constant, and the thickness variation is further suppressed.
[0005]
[Means for Solving the Problems]
In order to achieve the object, the thickness control method of the present invention is a mechanism for inserting a die into a die holding recess provided in the holder so as to face the baffle plate, and applying pressure from the circumferential direction to the die via the holder. When manufacturing an extruded profile using an extrusion die equipped with a die, an addition is made to the die according to the thickness variation of the extruded profile measured online so that the gap in the shaping space provided in the die is constant. It is characterized by controlling the pressure. Further, an extruded shape member is manufactured using an extrusion die having a mechanism that inserts a die into a die holding recess provided in the holder so as to face the baffle plate, and applies a pressing force to the die from the circumferential direction through the holder. At that time, the leg tip of the pressure adjusting rod inserted into the through hole extending from the outer periphery of the holder to the concave portion for holding the die is pressed against the peripheral surface of the die so that the gap of the shaping space provided in the die is constant . and controlling the pushing amount of force adjusting rod according to the thickness variation of the extruded profile.
[0006]
Embodiment
In the extrusion die according to the present invention, as seen in the main structure shown in FIG. 1, for example, the die 10 is nested in the holder 20 and fixedly held between the holder 20 and the baffle plate 30.
A shaping space 11 corresponding to the cross-sectional shape of the extruded profile is formed in the die 10. The die 10 is inserted into the die holding recess 21 of the holder 20 and is attached to a baffle plate 30 having a metal introducing portion 31. The die holding recess 21 is designed to have such a size that a slight gap 22 is formed between the inserted die 10 and the peripheral surface of the die 10.
The holder 20 has a through hole 23 extending from the outer periphery toward the center and opening in the die holding recess 21. A pressure adjusting rod 24 whose leg tip comes into contact with the peripheral surface of the die 10 is inserted into the through hole 23. By adjusting the protruding length of the pressure adjusting rod 24 protruding from the inner wall of the die holding recess 21, the force applied from the holder 20 to the die 10 can be changed. Although one pressing force adjusting rod 24 is shown in FIG. 1, the number and the insertion position of the pressing force adjusting rods 24 are appropriately determined in consideration of the size and cross-sectional shape of the extruded profile to be manufactured.
[0007]
In this structure, the holder 20 is connected and fixed to the baffle plate 30 by means such as bolts, but the die 10 and the holder 20 and the baffle plate 30 are not connected and fixed. A die 10 is sandwiched between them.
The die 10 is inserted into the die holding recess 21 of the holder 20 with the pressure adjusting rod 24 loosened. Next, the extrusion die 1 is assembled by applying the baffle plate 30 from the insertion side of the die 10 and connecting and fixing the baffle plate 30 to the holder 20. Thereafter, the pressure adjusting rod 24 is tightened to adjust the protruding length of the pressure adjusting rod 24 protruding from the inner wall of the die holding recess 21 so that the shaping space 11 of the die 10 has a specified dimension. The force applied to 10 is controlled.
[0008]
After the extrusion die 1 is heated to a predetermined temperature (for example, around 450 ° C.) by a die heater, it is set at a predetermined position on the side facing the stem 4 of the end platen 3 together with the bolster 2 as shown in FIG. The Next, the tip of the pressure adjusting rod 24 protruding in the outer peripheral direction of the extrusion die 1 is connected to the rod driving device 5.
When the container 6 containing the billet M preheated to a predetermined temperature (for example, around 450 ° C.) is brought into close contact with the extrusion die 1, and the billet M is pressed in the extrusion direction D by the stem 4, the billet M plastically flows and the die 10 An extruded shape S having a predetermined cross-sectional shape is manufactured through the shaping space 11.
[0009]
Since the holder 20 during extrusion molding is cooled down due to the dissipation of the retained heat, it heat shrinks. Due to the heat shrinkage of the holder 20, the inner method of the die holding recess 21 is reduced, and the gap 22 with the die 10 is narrowed. On the other hand, the die 10 is surrounded by the holder 20, and the gap 22 serves as a heat insulating layer, so that the heat conduction to the holder 20 is small. Moreover, since the high temperature billet M is in contact with the metal and processing heat is applied when the metal passes through the shaping space 11, the temperature drop of the die 10 is smaller than that of the holder 20, and the die 10 may be heated. . That is, the temperature drop rates of the die 10 and the holder 20 are different as shown in FIG. 3, and the temperature difference between the die 10 and the holder 20 is increased. When the contraction force of the holder 20 that has fallen greatly compared to the die 10 acts on the die 10, the die 10 is pressurized in the inner circumferential direction, and the gap in the shaping space 11 becomes small.
[0010]
Further, the extrusion processing force applied to the billet M during extrusion molding is normally set to a constant value in order to keep the speed of the extruded profile S extruded from the extrusion die 1 constant. On the other hand, a container sealing force caused by friction between the billet M and the container 6 acts on the die 10. A force that spreads outward through the metal in the metal introducing portion 31 is applied to the baffle plate 30, and the force is transmitted to the die 10 by a frictional force generated between the baffle plate 30 and the die 10. The frictional force between the baffle plate 30 and the die 10 depends on normal stress (container sealing force). However, since the contact area between the billet M and the container 6 decreases as the extrusion proceeds, the container sealing force becomes smaller at the rear end than at the front end of the billet M. Therefore, when viewed with one billet M, the container sealing force at the end of extrusion becomes smaller than that at the beginning of extrusion, and the gap of the shaping space 11 tends to narrow as the amount of expansion of the die 10 decreases.
[0011]
Since the temperature and the container sealing force fluctuate in this way during extrusion molding, the extruded shape S extruded from the extrusion die 1 is compared with the tip side when viewed from a single extruded shape S as shown in FIG. Then, the rear end side tends to be thinner. Further, when a plurality of billets M are continuously extruded, the subsequent extruded shape tends to be thinner than the previous extruded shape.
The decrease in the thickness of the extruded shape member S is caused by a change in the gap of the shaping space 11 due to fluctuations in the temperature of the extrusion die 1 and the container sealing force with the progress of extrusion. Therefore, in the present invention, by controlling the force applied to the die 10 so as to offset the influence due to fluctuations in temperature and container sealing force, the gap of the shaping space 11 is kept constant, and the wall thickness fluctuation is suppressed. Extruded profile S is manufactured.
[0012]
Specifically, a thickness gauge 7 is provided on the exit side of the end platen 3, and the thickness of the extruded shape member S fed from the extrusion die 1 is measured. As the thickness meter 7, an X-ray transmission method, a laser beam method, or the like can be used. The measurement value obtained by the thickness gauge 7 is sent to a control mechanism (not shown) and output to the rod drive device 5 as a control signal. In the rod driving device 5, the pressing amount of the pressure adjusting rod 24 is controlled according to the control signal, that is, the thickness of the extruded profile S, so that the gap of the shaping space 11 necessary for a predetermined thickness is maintained. The die 10 is pressurized.
In this way, when extrusion molding is performed while controlling the pressing amount of the pressure adjusting rod 24 during extrusion molding, the thickness variation of one extruded profile is 0 in comparison with the tip portion. The thickness reduction of the fifth extruded profile was suppressed to 0.05 mm or less in the five extruded profiles at 0.02 mm or less compared to the first extruded profile.
[0013]
As a method for suppressing fluctuations in the thickness of the extruded profile S, instead of the thickness gauge 7 for actually measuring the thickness of the extruded profile S, a puller that pulls the extruded profile S and the forward speed of the stem 4 or ram (not shown). ), The molding speed of the extruded profile S is obtained, the thickness of the extruded profile S calculated from the molding speed is calculated, and the pressing amount of the pressure adjusting rod 24 is calculated according to the calculation result. Can also be controlled. Alternatively, the pressing amount of the pressure adjusting rod 24 can be adjusted based on past results. Furthermore, instead of the rod driving device 5, a hydraulic mechanism or a gear mechanism that pressurizes the die 10 directly or indirectly may be incorporated. For example, when the pressing amount of the pressure adjusting rod 24 is adjusted by hydraulic control, the work of maintaining the gap of the shaping space 11 at a set value during extrusion molding becomes easy.
[0014]
【The invention's effect】
As described above, in the present invention, the pushing amount of the pressure adjusting rod that pressurizes the die from the circumferential direction in the void in the shaping space that is easily changed due to temperature fluctuations and container seal force fluctuations during extrusion molding. It is kept constant by controlling. For this reason, fluctuations in wall thickness due to fluctuations in temperature and container sealing force are suppressed, and an extruded shape with good shape accuracy can be obtained.
[Brief description of the drawings]
1A and 1B are a front view and a bb cross-sectional view of an extrusion die in which a die is inserted into a die holding concave portion of a holder.
FIG. 2 is a schematic diagram of an extrusion apparatus in which an extrusion die is set. FIG. 3 is a graph showing temperature changes of a die and a holder during extrusion molding. FIG. 4 is a graph showing an example of wall thickness variation caused by extrusion molding. Explanation】
1: Extrusion die 2: Bolster 3: End platen 4: Stem 5: Rod driving device 6: Container 7: Thickness gauge 10: Die 11: Shaped space 20: Holder 21: Die holding recess 22: Gap 23: Through hole 24: Pressure adjusting rod 30: Baffle plate 31: Metal introduction part M: Billet S: Extrusion profile D: Extrusion direction

Claims (2)

When a die is inserted into a die holding recess provided in a holder and opposed to a baffle plate, and an extruded shape member is manufactured using an extrusion die having a mechanism for applying pressure from the circumferential direction to the die through the holder, Thickness control of an extruded profile characterized by controlling the pressure applied to the die according to the thickness variation of the extruded profile measured online so that the gap in the shaping space provided in the die is constant Method. When a die is inserted into a die holding recess provided in a holder and opposed to a baffle plate, and an extruded shape member is manufactured using an extrusion die having a mechanism for applying pressure from the circumferential direction to the die through the holder, Push the leg tip of the pressure adjustment rod inserted into the through hole extending from the outer periphery of the holder to the concave part for holding the die against the peripheral surface of the die so that the gap in the shaping space provided in the die is constant, A method for controlling the thickness of an extruded profile that controls the amount of pressing of the pressure adjusting rod in accordance with the variation in the thickness of the material.

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