JPS6335367B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The disclosed technology belongs to the technical field of preventing machining accuracy defects due to temperature changes in machining frames of electrical machining equipment such as electric discharge machining equipment and machining equipment such as various machine tools. .

<Summary of the gist> The present invention provides a method in which a machining device such as an electric discharge machining device has a frame in the machining section for a workpiece, and the frame is slightly distorted due to temperature changes, causing accuracy errors. In such a case, the temperature of a predetermined part of the frame is detected and the distortion is forcibly corrected by feedback, so that the distortion always disappears and accuracy within a certain range is reproducible. The invention relates to a method for maintaining machining accuracy, and in particular, an anti-distortion liquid return pipe is provided in the frame connected to an anti-distortion liquid tank, and an anti-distortion liquid at a predetermined temperature is supplied to the return pipe, and at the same time on the supply side of the return pipe. Detects the difference between the temperature of the anti-distortion liquid on the return side and the temperature of the anti-distortion liquid on the return side, and determines either the flow rate or the flow rate of the anti-distortion liquid supplied so that the temperature difference maintains the set temperature difference. This invention relates to a method for maintaining machining accuracy of a machining device, which is controlled to maintain a distortion corresponding to a constant accuracy.

<Prior Art> As is well known, there are various types of processing devices for processing metal workpieces, and for example, a type that has an arm type frame as a wire processing part holding frame, such as a wire cut type electric discharge machining device. There are quite a few.

Therefore, in this type of processing equipment, the temperature conditions surrounding the equipment are not always constant, apart from special conditions such as processing workpieces under constant conditions in a constant temperature room. Rather, it often changes.

In addition, even if installed in a constant temperature room, the processing equipment generates a considerable amount of heat, so the processing equipment may be partially affected by heat radiation or conduction, either directly or indirectly through the processing fluid, etc. The reality is that temperature changes are unavoidable.

Under such conditions, the frame inevitably undergoes distortion due to temperature changes, even though it is not visible to the naked eye.As a result, the accuracy of precision machining of the workpiece cannot be performed as set, and the reproducibility of the product with the set tolerance accuracy is reduced. There was a drawback that the variation could not be maintained.

<Purpose and Structure of the Invention> In view of the above-mentioned problems, the present invention is proposed for the purpose of preventing distortion of the frame due to temperature changes and maintaining a predetermined processing accuracy. , an anti-distortion liquid at a predetermined temperature is supplied to the anti-distortion liquid return pipe attached to the frame, and the temperature difference between the return liquid that exchanges heat with the frame and returned and the supplied liquid is detected, and the temperature difference is kept constant. By controlling the flow rate or flow rate of the anti-distortion liquid supplied so as to achieve a set temperature difference of This feature is characterized in that machining accuracy can be maintained within a predetermined range.

<Example> Next, an example of the present invention will be described below with reference to the drawings.

Reference numeral 1 denotes a wire-cut electric discharge machining device as a machining device, and a U-shaped frame 3 is integrally and fixedly erected from one side of a base box 2 that houses a machining fluid tank (not shown) and the like.
is covered with a heat insulating material 4 such as glass fiber resin.

The frame 3 has an upper frame 3a and a lower frame 3b, and has supply and take-up reels 8, 9 for feeding the wire 5 as a processing section via guide and support pulleys 6, 7. is provided.

A ram 3c for holding the upper wire guide 5a is provided on the upper frame 3a so as to be movable in the vertical direction and fixable at any position.The ram 3c allows the vertical position of the guide 5a to be adjusted. adjusted.

Further, the stand 11a of the base box 2 is provided with a lower wire guide 5b corresponding to the upper wire guide 5a and a processing table 11, and the workpiece 12 is moved in the X and Y directions by a servo motor (not shown) according to a setting program. The machining movement is performed by numerical control, and machining fluid (not shown) is injected into the machining section.

In addition to the above aspects, in this invention, anti-distortion liquid return pipes 13 and 14 are attached to the inner wall of the frame 3, and the branched outgoing pipe 13 is connected to the anti-distortion liquid tank 15 via a pump 16 to a supply pipe 17. The return pipe 14 is connected to the tank 15 by a return pipe 18.

10 is a return pipe, which is connected between the downstream supply pipe 17 of the pump 16 and the tank 15 with a solenoid valve 19;
0 is a cooling or heating coil, and this coil 20 cools or heats the anti-distortion liquid 33 in the tank 15 so as to maintain it at a predetermined temperature.

Reference numerals 21 and 22 indicate temperature detection devices using direct heating type thermistors, which are interposed in the return pipe 14 and the supply pipe 17, respectively, and have power supplies 23 and 24, and sliding resistors 25 and 26, respectively. is attached.

The emitter of the transistor 27 is connected to the sliding resistor 26 and also to the power source 29 of the load resistor 28 from which the output from the collector is taken out.

A motor 30 for adjusting the opening and closing of the electromagnetic valve 19 is connected to a sliding resistor 31 of a variable setting power source, and the opening and closing of the electromagnetic valve 19 is adjusted by a voltage difference between the motor 30 and the sliding resistor 28 .

In such a wire-cut electric discharge machining apparatus 1, when feeding the wire 5 to the workpiece 12 and cutting it by moving the table 11 in the X and Y directions in a programmed manner, if the air temperature is at a certain temperature, the frame 3 is primarily On the other hand, due to the cover of the heat insulating material 4, no temperature influence appears, and the strain is small or in an initial strain state.On the other hand, when wire cut electric discharge machining is started, not only machining heat is generated from the machining part due to electric discharge energy, There are many sources of heat generation, such as a motor for winding and supplying the wire 5, a processing table drive motor, and a processing liquid supply motor.
It is collected downstream and recirculated,
In addition, wire cut electrical discharge machining often continues for several hours or even tens of hours. Therefore, if it continues for a long time, changes in outside temperature will be added to the effect, causing damage to the upright part of the frame 3 and the upper part. , and lower frame 3a, 3b portions, ram 3c portion, and
Distortion that affects machining accuracy appears around the machining table 11, such as the stand 11a, and in the 2 parts of the base box.

Therefore, in the present invention, prior to the start of processing, the anti-distortion liquid in the tank 15, which is adjusted to a predetermined temperature by the cooling or heating coil 20,
For example, the coolant 33 is pumped by the pump 16 from the supply pipe 17 to the return pipes 13, 14.
is supplied in circulation.

If machining is started in this state, the frame 3 that holds the machining part that generates significant heat will be heated, and in particular,
In wire cut electric discharge machining, the lower frame 3b, which absorbs the heat of the machining part and is easily affected by the heat from the flowing machining fluid, is heated to a large degree, and heat is generated between the coolant 33 in the return pipes 13 and 14 and the frame 3. When the exchange is performed, the temperature of the coolant 33 in the return pipe 14 increases, and a temperature difference occurs between the temperature of the coolant 33 in the supply pipe 17 and the coolant 33 in the supply pipe 17 .

The temperatures on the return side and the supply side are detected by the temperature detection devices 21 and 22 whose impedance changes depending on the temperature, and voltage drops corresponding to the respective temperatures are applied to the sliding resistors 25 and 26. It is formed.

The temperature difference between the return side and the supply side is due to this sliding resistance 25,
This is detected as the difference between each voltage drop due to 26.

Therefore, due to this voltage difference, the transistor 27
The conduction state of is controlled, and a voltage drop is formed across the sliding resistor 28.

The drive of the motor 30 is controlled by the voltage difference between the voltage effect formed on the resistance resistor 32 by the setting power supply 31 and the voltage drop formed on the sliding resistance 28, and the opening of the electromagnetic valve 19 is controlled according to the temperature difference. The degree will be adjusted.

The opening degree of the electromagnetic valve 19 is set such that when the detected temperature difference becomes larger than the contact temperature, the opening degree is decreased, and when the detected temperature difference becomes smaller than the set temperature difference, the opening degree is increased. Let it be adjusted.

That is, when a large amount of heat is supplied to the frame 3, especially the lower frame 3b, and the temperature of the frame tends to rise, the temperature of the coolant 33 in the return pipe 14 rises, and the temperature of the coolant 33 on the supply side is maintained at a predetermined temperature. The temperature difference with the coolant 33 will increase, and in such a case, the opening degree of the electromagnetic valve 19 is controlled to decrease based on the detection signal of this increase in temperature difference, so that the temperature difference between the tank 15 and the coolant 33 is decreased through the return pipe 10.
While the flow rate of the coolant 33 returning to the supply pipe 17 decreases, the return pipe 13,1
The flow rate of coolant 33 supplied to 4 increases.

As a result, the cooling effect on the frame is enhanced, and the amount of heat absorbed from the frame is increased, thereby preventing the temperature of the frame from rising, or reducing the temperature of the frame and maintaining it at a predetermined temperature.
The temperature difference also decreases and returns to the set temperature difference.

In addition, when the heat supply to the frame is small and the cooling effect of the coolant 33 is too strong and the temperature of the frame tends to decrease, the temperature of the coolant 33 in the return pipe 14 decreases and the supply is maintained at a predetermined temperature. The temperature difference with the coolant 33 on the side will decrease, but in such a case, the opening degree of the electromagnetic valve 19 is controlled to increase based on the detection signal of the decrease in temperature difference, and the temperature difference between the tank 15 and the coolant 33 is increased through the return pipe 10.
by increasing the flow rate of the coolant 33 returning to the return pipe 1 through the supply pipe 17.
3, 14 is reduced.

As a result, the cooling effect on the frame is reduced, and the amount of heat absorbed from the frame is reduced, thereby preventing the temperature of the frame from decreasing, or increasing the temperature of the frame and maintaining it at a predetermined temperature. The temperature difference increases and returns to the set temperature difference.

In this way, the temperature difference between the temperature of the anti-distortion liquid on the supply side and the temperature of the anti-distortion liquid on the return side is always maintained at a constant temperature difference. The frame temperature is always maintained at the specified temperature regardless of the amount of heat generated during the process or changes in the environmental temperature over time, which prevents distortion due to temperature changes in the frame and allows for good reproducibility with machining accuracy within the specified range. Processing can also be carried out over a long period of time.

The above embodiment has been described in the case where the present invention is applied to a part of the frame 3 and the lower frame 3b, but of course the entire frame 3, especially the upper frame 3
It is preferable to apply it in parallel to the ram 3c and the stand 11.
It is preferable to apply the method in parallel also to the area around the processing table 11, the base box 2, etc.

It goes without saying that the embodiment of the present invention is not limited to the above-mentioned embodiment, and various embodiments can be adopted, for example, the temperature on the supply side may be set to the tank temperature as the reference temperature. can be,
Further, the anti-distortion liquid is not limited to a coolant, but may also be water or the like, and the processing device can be applied to any type of processing device in which thermal distortion is formed.

Furthermore, in place of or in combination with the electromagnetic valve 19, an electromagnetic valve or the like capable of controlling the flow rate may be provided in each of the outgoing routes to the upper and lower frames 3a and 3b, or in each of the return pipes 13 and 14. The opening degree of the valve may be changed and controlled.

Furthermore, instead of controlling the flow rate of the anti-distortion liquid, the flow rate may be controlled, and the flow rate control provides substantially the same effect as the flow rate control.

<Effects of the Invention> As described above, according to the present invention, an anti-distortion liquid return pipe is attached to the frame supporting the processing section of the processing device and connected to the anti-distortion liquid tank, and the anti-distortion liquid at a set temperature is supplied. By controlling the flow rate or flow rate to maintain a constant temperature difference between the supply side temperature and the return side temperature, it is possible to prevent changes over time in the amount of heat generated during the operation of processing equipment and the environmental temperature. Regardless of the situation, the temperature of the frame can always be maintained at the specified temperature, preventing distortion due to temperature changes in the frame, allowing processing with good reproducibility with processing accuracy within a specified range, and processing over a long period of time. I can do it. In addition, since the present invention changes and controls the flow rate or flow rate of the anti-distortion liquid, it is less likely to occur during processing than when the temperature of the frame is controlled by changing the temperature of the anti-distortion liquid supplied. The frame temperature can be maintained and controlled at a predetermined temperature by responding quickly and responsively to changes in the amount of heat supplied to the frame due to changes in the amount of heat supplied to the frame or changes in environmental temperature, and has the effect of preventing distortion due to temperature changes in the frame. is large.

[Brief explanation of the drawing]

The drawings are explanatory diagrams of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Processing device, 5... Processing part, 3... Frame, 33... Distortion prevention liquid, 13, 14... Return pipe.

Claims (1)

[Claims] 1. A method for maintaining machining accuracy by preventing distortion due to temperature changes in a frame that holds a machining part of a machining device, in which a distortion prevention liquid return pipe is attached to the frame, and a distortion prevention liquid at a predetermined temperature is supplied to the return pipe. While supplying, the difference between the temperature of the anti-distortion liquid on the supply side of the return pipe and the temperature of the anti-distortion liquid on the return side is detected, and the temperature difference is supplied so as to maintain the set temperature difference. A method for maintaining machining accuracy in a machining device, characterized in that distortion caused by temperature changes in the frame is prevented by controlling either the flow rate or the flow velocity of the distortion prevention liquid.