JP2709335B2 - Extrusion press and extrusion press pressure control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion press and an extrusion press pressure control method, and more particularly to an extrusion press and an extrusion press pressure capable of improving the product yield by keeping the extrusion force constant throughout the extrusion process. It relates to a control method.

[0002]

2. Description of the Related Art In a conventional extrusion press, an end platen and a main cylinder are connected by a tie rod. A container in which a material billet is loaded is arranged on the end platen side with a die interposed therebetween, and a stem is mounted on a main cylinder side on a crosshead that is driven integrally with a ram coming in and out of the container. Then, the stem is pressed and extruded toward a billet loaded in the container by a pushing force of a main cylinder device, and a predetermined product is extruded from a die.

[0003] In such an extrusion press, it is desirable that the extrusion force be constant throughout the extrusion process. However, since the length of the billet in the container is gradually shortened in the extrusion process, the extrusion force between the start and the end of the extrusion is reduced. Usually, the former requires a higher extrusion force. That is, even if the extrusion resistance of the die is constant, the frictional resistance between the container and the billet decreases as the length of the billet decreases, so that the required extrusion force gradually decreases as a whole.
As a result, when the change of the extrusion pressure with respect to the stroke of the stem is obtained, as shown in FIG. 5, after the upset pressure is given by pressurizing the stem, a peak pushing force F ₀ appears at the extrusion start point, This gradually decreases with the progress of the stroke (hatched portion in the figure).

[0004]

When the extrusion pressure changes during the extrusion process as described above, the force acting on the end platen of the press changes, and as a result, the displacement of the end platen and die during the extrusion process. And the amount of deflection is not constant. Therefore, there is a problem that the thickness and shape of the product obtained by the conventional extrusion press are not uniform in the longitudinal direction of the extrusion. That is, at the start of extrusion, the wall thickness is large,
The phenomenon that the thickness becomes thinner as the extrusion is completed is caused, which causes a decrease in the product yield. In this case, even if the main cylinder device is pressurized and controlled so as to prevent a reduction in the pushing force, there is a problem that the pushing force cannot be increased by the main cylinder device because the product is extruded through the die.

[0005] The change in the required pushing force is caused by the fact that the frictional force between the billet and the inner wall of the container decreases depending on the billet length.
There is also a problem that a fluctuation of the container sealing force with respect to the dies occurs, causing a so-called flower blooming phenomenon in which billets blow out from the sealed portions.

The present invention focuses on the above-mentioned conventional problems, and can always produce a uniform extruded product by constantly generating a constant pushing force in an extrusion process, and maintain a constant container sealing force. It is an object of the present invention to provide an extrusion press and an extrusion press pressure control method capable of preventing occurrence of a phenomenon and thereby improving product yield.

[0007]

To achieve the above object, an extrusion press according to the present invention is an extrusion press for extruding a billet loaded in a container by a main cylinder device from a die with a stem to form a product. An auxiliary cylinder device that performs auxiliary extrusion pressurization is connected to the container, and when a pressing force by the main cylinder device is detected.
Calculate the deviation from the peak value and calculate the deviation
The lowering pressure is used as the supplemental pressure to the auxiliary cylinder device.
It has a configuration with control means that can output.
You.

Further, the extrusion press pressure control method according to the present invention detects the peak pressure at the start of extrusion by the main cylinder device in the extrusion step of the extrusion press, and detects the progress pressure of the extrusion in the extrusion process, and determines the peak pressure and When the difference from the extrusion pressure is calculated, the auxiliary cylinder connected to the container outputs the difference pushing force to perform the equal-pressure extrusion.

[0009]

According to the above construction, when the friction between the billet and the inner wall of the container is reduced by extrusion and the pushing force is reduced,
A pushing force corresponding to the decrease amount is generated by the auxiliary cylinder device, and the container can be pressurized. That is, it is possible to perform the extrusion while maintaining the peak pressure at the start of the extrusion in all the steps of the extrusion. For this reason, the displacement amount of the end platen or the die can be kept constant, and the thickness and shape of the product do not change, so that the yield of the product can be improved. In addition, the complementary pressing force corresponds to the container sealing force and prevents the sealing force from lowering, so that the surface pressure of the container dies can be kept constant, preventing the flower bloom phenomenon from occurring, and also preventing the occurrence of burrs. It can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of an extrusion press and an extrusion press pressure control method according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an extrusion press according to an embodiment, and FIG. 2 is a sectional view of an extrusion step. As shown in these figures, in the extrusion press, an end platen 10 and a main cylinder device 12 are arranged to face each other, and both are connected by a plurality of main tie rods 14. End platen 10
A container 18 is arranged on the inner surface side of a die 16 having an extrusion hole formed therebetween. A billet 20 is loaded in the container 18 and the container 18 is extruded and pressed toward the die 16 to obtain a cross section corresponding to the die hole 16A. Products are extruded.

Main cylinder device 1 for generating a pushing force
Reference numeral 2 denotes a main cylinder 12A having a built-in main ram 12B, which can be pressed and moved toward the container 18. A main crosshead 22 is attached to a front end of the main ram 12B. An extrusion stem 24 is directed toward the container 18 at the center of the front portion so as to be arranged concentrically with the billet loading hole 18A of the container 18. It is mounted in a protruding state. Therefore, when the main cylinder device 12 is driven to advance the crosshead 22, the extrusion stem 24 is inserted into the loading hole 18A of the container 18 and presses the rear end face of the loaded billet 20 to extrude the product 20A. is there.

A side cylinder device 26 is attached to the main cylinder 12A in parallel with the center of extrusion, and its rod 26A is connected to the main crosshead 22. As a result, the extrusion stem 24 is initially moved to a position close to the container 18 as a preparation step for the extrusion step, and the extrusion press operation is adjusted so as to be performed by both the main cylinder device 12 and the side cylinder device 26.

Here, in the extrusion press according to the embodiment, a plurality of auxiliary cylinder devices 28 are provided on the front surface of the main crosshead 22 so as to surround the extrusion stem 24. This auxiliary cylinder device 28
Is constituted by a cylinder 28A fixedly attached to the crosshead 22 and a rod 28B driven in and out of the cylinder 28A. The rod 28B is attached so that the extension direction of the rod 28B is parallel to the extrusion stem 24. The tip of the rod 28B can contact the four corners of the container 18 so that the container 18 can be pushed out by hydraulic drive.

Referring to FIG. 1, the configuration of a hydraulic circuit for performing auxiliary extrusion driving by the auxiliary cylinder device 28 and a hydraulic circuit for driving the main cylinder device 12 will be described.

First, the drive circuit of the main cylinder device 12 is provided with a variable displacement type hydraulic pump 30, and the discharge hydraulic pressure from the hydraulic pump 30 is supplied to the main cylinder device 12 and the side cylinder device 26 via a hydraulic passage 32. . A pressure sensor 3 for detecting the extrusion pressure is provided in the hydraulic passage 32.
4 is attached, and outputs the detected pushing pressure to the controller 36.

Further, a hydraulic pump 38 for supplying a hydraulic pressure to the auxiliary cylinder device 28 is separately provided, and an oil for driving the rod 28B to project from the pump 38 to each auxiliary cylinder device 28 through the auxiliary hydraulic passage 40 is provided. It is designed to generate pressure. The auxiliary hydraulic passage 40 is provided with a branch passage 42 in which a variable electromagnetic relief valve 44 is interposed. That is, by changing the relief pressure of the electromagnetic relief valve 44, the pressure oil is released from the auxiliary cylinder device 28, so that the pushing force of the auxiliary cylinder device 28 to the container 18 can be adjusted. The opening / closing operation amount of the electromagnetic relief valve 44 is performed in accordance with a set command value based on a control signal from the controller 36, and is set to a predetermined opening via an amplifier 46.

By the way, during the extrusion process, the main cylinder
The pushing action is performed by the device 12 and the side cylinder device 26.
The maximum required extrusion force F at the start of extrusion₀Is dice 1
Extrusion force F acting on 6_aAnd billet 20 and container
Maximum frictional force F with tip 18_b(FIGS. 2 and 3
reference). When the extrusion stroke reaches S, the billet friction force
Decreases and F_bsExtrusion required force from main line
Is F_S= F_a+ F_bsBecomes Therefore, the maximum extrusion force
F₀At the S stroke position_S1= F₀-F only s
Extrusion requirements will be reduced.

When a pressure is generated in the auxiliary cylinder device 28 and the pushing load is set to F _S1 , the pushing load F _S1 acts on the main cylinder device 12 and the end platen 10 via the main tie rod 14. Will be. If the correction force F _S1 (= F ₀ −F _s ) is applied when the maximum extrusion load reaches F _S in the extrusion process, the pushing force can be kept at F ₀ = constant.

Therefore, the controller 36 controls the auxiliary cylinder device 28 to generate the correction force F _S1 . FIG. 4 shows the processing by the controller 36. That is, the controller 36 receives the detection signal from the pressure sensor 34 (step 10).
0), the memory being built so that to store the maximum value of the detected pressure as a peak pressure P _M (Step 1
10). At the same time, continuously input the detected pressure (step 1
20), and is configured to compare operation with the peak pressure P _M this as elapsed pressure P _C. Then, these differential pressures ΔP _A are calculated (step 130), and when this pressure exceeds the allowable value, it is determined that the pushing force of the extrusion stem 24 by the main cylinder device 12 and the side cylinder device 26 has decreased. Therefore, the pressure increase to the auxiliary cylinder device 28 necessary to generate the pushing force corresponding to the decrease is calculated (step 140). This means that the total pressure area of the main cylinder device 12 and the side cylinder device 26 is A ₁ ,
If the pressure area of the auxiliary cylinder device 28 is A ₂ and the correction pressure is ΔP _B ,

[0021]

## EQU1 ## Since it is obtained as ΔP _B = ΔP _A · A ₁ / A ₂ , the arithmetic processing based on the expression is performed.

The auxiliary pressure ΔP _B thus obtained
The adding to the current pressure P _B of the auxiliary cylinder device 28 (step 150). Then, the extrusion stroke is detected in advance by a stroke sensor or the like, and it is determined whether or not the extrusion has been completed (step 160). When the extrusion process is being performed, a voltage conversion process corresponding to the calculated value is performed (step 160). 170), this is output as a control signal to the amplifier 46 (step 180), and the relief valve 44 is driven to open and close so that the auxiliary cylinder device 28 generates a pushing force that complements the decrease in the pushing force on the main line side. (Step 190). When it is determined in step 160 that the extrusion end position has been reached, zero reset processing is performed to prepare for the next extrusion step (step 200).

As described above, the controller 36 detects the extrusion pressure in the main line and drives the auxiliary cylinder to apply a pushing force to the container 18 so that the peak pressure is always maintained in the extrusion process. Can be kept constant over the entire stroke. As a result, the amount of displacement and the amount of bending of the end platen 10, the die 16 and the like can be kept constant, whereby the thickness and shape of the extruded product 20A can be made uniform in the longitudinal direction,
The product yield can be greatly improved.

Also, since the container seal holding force can be kept constant during the extrusion process, the surface pressure of the container seal surface can be kept at a constant high pressure, and the occurrence of burrs due to flower blooming from the seal surface can be effectively prevented. Can be.

In the above embodiment, the auxiliary cylinder device 2
8, the generation of the auxiliary pushing force is continuously changed by the variable electromagnetic relief valve 44. A plurality of opening / closing relief valves are mounted in parallel on the branch passage 42, and the relief pressure is controlled by a combination of the opening / closing switching. You may make it control. In this case, a stepwise auxiliary pressure is output, but it is possible to keep the required extrusion force constant within a predetermined range.

[0026]

As described above, according to the present invention,
An auxiliary cylinder that extrudes and presses the container is provided separately from the main cylinder device, which complements the reduction of the pushing force due to the change in billet length, so that the displacement and deflection of the end platen and die are kept constant Thus, the thickness and shape of the extruded product can be made uniform over the entire length of the extruded length, and the product yield can be greatly improved. In addition, since the surface pressure of the container seal portion is made constant at the same time, an excellent effect of effectively preventing burrs can be obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an extrusion press according to an embodiment.

FIG. 2 is a cross-sectional view of the press during an extrusion step.

FIG. 3 is a characteristic diagram of an extruding force of the press.

FIG. 4 is a flowchart of driving control of an auxiliary cylinder of the press.

FIG. 5 is a characteristic diagram of an extruding force of a conventional extruding press.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 End platen 12 Main cylinder device 14 Main tie rod 16 Dice 18 Container 20 Billet 20A Extruded product 22 Main crosshead 24 Extrusion stem 26 Side cylinder device 28 Auxiliary cylinder device 30 Hydraulic pump 32 Hydraulic passage 34 Pressure sensor 36 Controller 38 Hydraulic pump for auxiliary 40 auxiliary hydraulic passage 42 branch passage 44 variable electromagnetic relief valve 46 amplifier

Claims (2)

(57) [Claims] 1. An extrusion press for forming a product by extruding a billet loaded in a container from a die with a stem by a main cylinder device, wherein an auxiliary cylinder device for performing auxiliary extrusion pressurization is connected to the container. Pressing force is detected and its peak value is detected.
Calculate the deviation from the above and complement the drop pressure corresponding to the deviation
A system that can output the pressure to the auxiliary cylinder device
An extrusion press having control means . 2. In the extrusion process of an extrusion press, when a peak pressure at the start of extrusion by a main cylinder device is detected, and an extrusion pressure in an extrusion process is detected, and a difference between the peak pressure and the extrusion pressure is calculated. And an auxiliary cylinder connected to a container to output the differential pressing force to perform equal-pressure extrusion.