JPS5855860B2 - Method of controlling mold clamping force of die casting machine - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mold clamping force control method for a die casting machine.
In particular, it relates to a mold clamping force control method for a type of die casting machine in which a tie bar is disposed between a fixed platen and a mold clamping force generator, and the mold is clamped by the restoring force of the tension of the tie bar generated when pressing the movable platen. .

FIG. 1 is a diagram showing the overall configuration of the die casting machine.

In FIG. 1, a plurality of tie bars (usually four) parallel to each other are connected between a fixed platen 14 fixed on a base 12 and a mold clamping force generator support section 16 placed on the base. 18 are provided.

Each tie bar 18 has a nut 2 attached to the fixed platen 14.
Although the support part 16 is fixed in a fixed position by
It is latched to by a tie bar nut 22 whose position is adjustable.

The mold clamping force generator support part 16 is configured as a plate movable with respect to the base 12, and is configured as a plate that is movable with respect to the base 12, and
By adjusting 2, the position relative to the fixed platen 14 can be adjusted (die-hide adjustment).

A mold clamping cylinder 24 as a mold clamping completion generating device is fixed to the support part 16, and by expanding and contracting its piston rod 24A, the movable platen 26 fitted to the tie bar 18 can be moved closer to the fixed platen 14. It is designed so that it can be moved backwards.

In the illustrated example, the movable platen is driven by the mold clamping cylinder 24 via a toggle link mechanism 28.

A movable mold 30 and a fixed mold 32 are fixed to opposing surfaces of the movable platen 26 and the fixed platen 14.

An injection cylinder 34 and a hot water supply device 36 are provided on the fixed platen side, so that molten metal such as aluminum alloy can be injected into the clamped mold.

In such a die casting machine, the toggle link mechanism 28 is tensioned in the mold clamping cylinder 24 to generate tension in the plurality of (four) tie bars 18, and the mold is clamped with a force that attempts to restore the tension.

The mold clamping force is the same as the relaxation of tension generated in the plurality of (four) tie bars 18.

However, if the humidity of the molds 30, 32 changes during the casting operation, the thermal expansion of the molds changes, resulting in changes in mold height and die bite.

At this time, if the length of the part of the total length of each tie bar 18 where tension is generated, that is, the natural length of the part between the mold clamping force generator support part 16 and the fixed platen 14, does not change, each The tension generated in the tie bars 18 changes, and the mold clamping force changes.

For example, even though the mold temperature has increased, tie bar 18
If the natural length of is S as it is, the tie bar during mold clamping will be extended extra and the mold clamping force will increase, making it difficult for air to escape from the mold 30.32 dividing surface (mating surface) and forming cavities. more likely to occur.

Furthermore, if the mold temperature rises excessively, the toggle link mechanism cannot be fully tensioned, and mold clamping cannot be completed.

On the other hand, when the temperature of the molds 30 and 32 decreases, the mold clamping force decreases, and the resistance to the mold opening force due to the molten metal injection pressure decreases, causing a problem that a huge flash is generated.

Therefore, if the mold temperature changes during casting and the thermal expansion of the mold changes, the tie bar will change by an amount corresponding to the change in mold temperature.
By changing the natural length of 8, it is possible to adjust so that the same tension (force equivalent to the mold closing force) is always applied.

That is, the same tension (same strain) can be maintained by changing the amount of movement of the movable mold (movable platen 26) and adjusting the natural length of the tie bars.

This mechanism for adjusting the natural length of the tie bar is called a die bite adjustment device.

This die bite adjustment is performed by rotating the tie bar nut 22 shown in Fig. 1, but in the conventional die bite adjustment, the caster adjusts the tie bar using a strain gauge or a tie bar elongation measuring device. The elongation changes were monitored, and when an abnormality was discovered, the casting operation was stopped and the die bite was adjusted manually.

For this reason, it takes a lot of time and manpower to adjust the die bite,
Adjusting the mold clamping force was complicated and difficult.

The purpose of the present invention is to eliminate such drawbacks of the conventional technology, and by connecting a tie bar elongation measuring device and a die bite adjustment mechanism to a computer such as a microcomputer, it is possible to automatically adjust the die bite without stopping casting work. The present invention provides a mold clamping force control method for a die casting machine that can perform the following steps.

That is, according to the present invention, the elongation of the portion where tension is generated during mold clamping is detected for a plurality of tie bars disposed between the fixed platen and the mold clamping force generating device support, and the elongation of each tie bar is compared. When the arithmetic average is less than the set lower limit, the mold is opened without casting, and the length of the tension-generating part of the tie bar is shortened by the difference from the set median value, and the arithmetic average of the elongation of each tie bar becomes the set upper limit. If the setting exceeds the upper limit and is between the machine tolerance limit, casting is performed without opening the mold, and the length of the tension-generating part of the tie bar is lengthened by the difference from the set median value before the mold is closed for the next casting. When the arithmetic average of the elongations of each tie bar is greater than the mechanical tolerance limit, the mold is opened without casting, and the length of the tension-generating part of the tie bar is lengthened by the difference from the set median value. A mold clamping force control method for a die casting machine is provided, which is characterized in that the arithmetic average of the elongation of each tie bar during mold clamping is automatically suppressed within a set range.

FIG. 2 is a flow chart showing one embodiment of the present invention.

In FIG. 2, when the control method of the present invention is carried out in 5 TART, first, in block 101, each tie bar at the time of mold opening (before mold clamping) is checked at the part where tension is generated during mold closing (the support part 16 and the fixed platen 14). The position Lo of a fixed point (for example, point A in FIG. 1) where no tension occurs with respect to a fixed point (for example, point B in FIG. 1) between the

At step 102, the mold is clamped.

Next, in step 103, for each tie bar during mold clamping, the position LI is measured between a fixed point (point A) where tension occurs and a fixed point (point B) where tension does not occur for each tie bar.

104 and its elongation for each tie bar 18 JLLI-L
(Calculate i.

In step 105, the average value ALM of the elongation JL of each tie bar is calculated.

Here, N represents the number of tie bars 18.

At 106, the average value of tie bar elongation is compared between ALM and the set upper limit JLH.

If the comparison judgment result in 106 is JLM≦JLH, proceed to 107, and in 107, the average value of tie bar elongation JL
Compare M with the setting lower limit JLL.

If the result of the comparison in step 107 is JLM≧JLL, the process proceeds to step 108 and N casting is performed.

On the other hand, the comparison judgment result in 107 is JLM, <JL
If it is L, proceed to 118, open the mold in 118 without casting, and in the next step 119, set median value ((difference from L (JL - JLM)) and the tension of multiple tie bars will be generated. Shorten the length of a section.

This length adjustment is performed by rotating the tie bar nut 22 of FIG. 1 by a predetermined amount using a die bite adjustment mechanism automatically controlled by a microcomputer or the like.

After adjusting the die bite by adjusting the length of the tie bar in step 119, the process returns immediately after 5TART and performs the process again.

If the comparison judgment in step 106 is JLM>JLH, the process proceeds to step 128, where the JLM is compared with the machine allowable limit JLU which exceeds the set upper limit JLH.

If the result of the comparative judgment in step 128 is JLM≦JLU, that is, the average value of tie bar elongation is between the set upper limit and the machine allowable limit, casting is performed without opening the mold in the next step 129, and the setting center is changed in step 130. Difference with value 7 King (JLM-
The tension-generating portion of the tie bar is lengthened by JL) and returned to immediately after the 5TART 100 for the next casting step (processing cycle).

On the other hand, the result of comparison judgment in 128 is ILM>ALU
In other words, when the average value of tie bar elongation is above the set upper limit, the mold is opened before casting at step 139, and the mold is opened at step 14.
0, the length of the local part where tension is generated in each tie bar is lengthened by the difference (JLM-JL) from the set median value JL.

After correcting the tie bar length, the process returns to immediately after 5TART and repeats the processing procedure from the beginning.

The mold clamping force control method for a die casting machine according to the present invention automatically corrects the mold clamping force to a predetermined value by the processing procedure described above in the embodiment in FIG. Since the mold clamping force is automatically maintained within the set range, the quality of the die-cast product can be maintained automatically, and the efficiency of the casting operation can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing the overall structure of a die-casting machine suitable for carrying out the control method of the present invention, and FIG. 2 is a flowchart showing the processing procedure of one embodiment of the control method of the present invention. 14... Fixed platen, 16... Mold clamping force generator support part, 18... Tie bar, 22
... Tie bar nut, 24 ... Mold clamping cylinder (mold clamping force generating device), 26 ... Movable platen, 28 ... Toggle link mechanism, 30.
...Movable mold, 32...Fixed mold, A.
...Fixed point of the tension-generating part of the tie bar, B...
・・・Fixed point in the part of the tie bar where no tension occurs.

Claims (1)

[Claims] 1. In a die-casting machine configured to detect the elongation of a portion of a plurality of tie bars disposed between a fixed platen and a mold clamping force generating device support part, where tension is generated during mold clamping, and adjust the mold clamping force, the tie bars The mold is opened when the arithmetic average of elongation is less than the set lower limit, and the length of the tension-generating part of the tie bar is shortened by the difference from the set median value.
Casting is performed when the arithmetic average of the elongation of each tie bar is between the set upper limit and the machine tolerance limit exceeding the set upper limit, and the tie bar tension is increased by the difference from the set median value until the next casting mold clamping. When the arithmetic average of the elongation of each tie bar is greater than or equal to the machine tolerance limit, the mold is opened, and the length of the tension-generating part of the tie bar is increased by the difference from the set median value. B. A mold clamping force control method for a die casting machine, characterized in that the arithmetic average of the elongation of each tie bar during mold clamping is automatically suppressed within a set range.