JPS634309A - Working liquid cooling device - Google Patents

Abstract

PURPOSE:To improve working accuracy by varying the temperature of working liquid which flows between electrodes continuously according to ambient temperature. CONSTITUTION:Temperature data obtained by a sensor 18 for working liquid temperature detection which detects the temperature of the working liquid 3 interposed between a wire electrode 2 and a work 1 and a sensor 19 for ambient temperature detection are compared with each other. Then when the temperature of the working liquid between the wire electrode 2 and work 1 is lower than the specific range of the ambient temperature, the rotating speed of a compressing machine 16c for refrigeration is lowered by frequency conversion to lower its cooling ability. When the working liquid temperature is higher, on the other hand, the rotating speed of the compressing machine 16c is increased to increase the cooling ability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a machining fluid cooling device in a wire electrical discharge machining device or the like.

[Conventional technology]

Fig. 3 is a configuration diagram showing a normal wire electrical discharge machining device, in which (1) is a workpiece, the hole wall of the initial hole (1a) previously drilled with a drill etc. and the wire electrode (2). An insulating working fluid (3) is interposed between them. This processing liquid (3
) is injected from a tank (4) by a supply pump (5) into the gap between the liquid to be processed (1) and the wire electrode (2) by a nozzle (6).

The relative movement between the workpiece (1) and the wire electrode (2) is effected by the table αυ on which the workpiece (1) is placed. This table αυ is driven by an X-axis motor circle and a Y-axis motor α3, and the relative movement between the workpiece (1) and the wire electrode (2-axis) is caused by interlocking two-dimensional planes within the X and Y-axis planes. becomes.

The wire electrode (2) is supplied by the wire electrode supply reel (katana), the lower wire electrode guide (8A), the workpiece (
1), reaches the upper wire electrode (8B), and is wound up by a tension roller αQ that winds up the wire electrode (2). The control device that controls the drive of the X and Y axis motors az and uni is an NC device, a copying device, or an electric machine, and the processing power source that supplies electrical energy < IS1 is DC mtA (15 m), switching element (15b), a current limiting resistor (15c), and a control circuit (15d) that controls the switching element (15b).

In the wire electrical discharge machining equipment configured as above, the temperature of the machining fluid (3) is controlled only within a certain range of cooling capacity, so the heat amount of the machining fluid (3) changes excessively with respect to the ambient temperature. Since the temperature followability of the machining fluid (3) during this process is extremely poor, the temperature cannot be controlled with a stable heat cycle.

Further, the factor that most affects the machining accuracy of the workpiece is deformation of the mechanical system due to heat.

For example, the coefficient of thermal expansion of iron used as a material for mechanical structures is approximately 11P when the temperature of 1m long iron increases by 1°C.
This causes an elongation of Tt. Therefore, for example, in a table, arm, etc. with a length of about 700n, a temperature change of 1°C will cause a deformation of about 8) bm, but the expansion and contraction due to temperature changes of each part of the mechanical system will cause this temperature change. Correspondingly, if they occur completely simultaneously, there will be no dimensional difference between them due to expansion and contraction. In other words, the machining fluid (3
) can always follow the temperature, each part of the mechanical system described above will expand and contract in response to changes in the surrounding temperature, so dimensional differences between these mechanical systems can be minimized.

[Problem that the invention seeks to solve]

In the conventional wire electrical discharge machining equipment as described above, the ambient temperature of the mechanical system increases due to heat radiated between the wire electrode (2) and the workpiece (υ) or from other heating elements such as the motor system. However, a temperature difference occurs between the wire electrode (2) and the workpiece (1) and the ambient temperature, or a temperature difference between the mechanical system and the ambient temperature.
Since the deformation due to thermal stress occurring in the workpiece (1) and the mechanical system is different, this has a significant negative effect on the machining accuracy of the workpiece (1). When the calorific value of the machining fluid (3) changes transiently, there is a problem in that the temperature of the machining fluid (3) follows the ambient temperature extremely rapidly, making it difficult to maintain stable cooling characteristics of the machining fluid.

This invention was made to solve this problem, and by synchronizing the temperature change of the machining fluid flowing between the machining parts and the ambient temperature, the heat between the workpiece and the machine structure can be reduced. The object of the present invention is to obtain a machining fluid cooling device that improves machining accuracy by continuously uniformizing deformation and minimizing relative dimensional differences caused by temperature changes.

[Means for solving problems]

The machining fluid cooling device according to the present invention individually detects the peripheral E temperature of the machining device and the machining fluid temperature near the machining gap, and continuously adjusts the machining fluid temperature so that the difference between these temperatures falls within a predetermined temperature range. Furthermore, by setting the range of cooling capacity required in response to changes in the heat amount of the machining fluid in multiple stages, and by switching the cooling capability, it is possible to provide cooling capability in a wide range of ranges, and to adjust the temperature of the machining fluid in response to changes in ambient temperature. This is to obtain continuous followability.

[For production]

In this invention, the difference between the ambient temperature of the processing device and the temperature of the processing fluid near the workpiece is converted into a frequency, and the rotation speed of the drive motor of the refrigeration compressor is changed according to the temperature difference via an inverter. In addition to continuously controlling the temperature of the machining fluid, multiple opening/closing means installed in the refrigerant gas circulation path in the machining fluid cooling device are operated in multiple stages in response to transient fluctuations in the heat amount of the machining fluid. control by switching the cooling capacity.

[Embodiment of the Invention] FIG. 1 is a block diagram showing a machining fluid cooling device in a wire electrical discharge machining apparatus according to an embodiment of the present invention.
(5) is the same part as the same reference numeral in FIG. 4 showing the conventional example.

Qe is a cooling device, which includes a cooling air supply pump (16a
) and condenser (16b), refrigeration compressor (16c), blower (16d), solenoid valve (16f), throttle (16g
) consists of a refrigeration cycle circuit. At home, the frequency conversion unit is used, as shown in Figure 2 in detail.
A converter (17c) converts each of the sensors a to 9 for detecting machining fluid temperature and the sensor 9 for detecting ambient g temperature.

(17d) into a voltage value, and these converters (
17e), (17d) O output M tt V/F converter (
17bE is input, and the output of this V/F converter (17b) is input to the inverter αη, and the output converted here drives the refrigeration compressor (16c).

In the machining fluid cooling M[ of the present invention configured as described above, the temperature of the machining fluid (3) interposed between the wire electrode (2) and the workpiece (1) is detected as shown in FIG. These sensors u8) include a machining fluid temperature detection sensor aa and an ambient temperature detection sensor 4.

(The temperature gain detected in step 19 was compared, and the wire electrode (2
) and the workpiece (1) is lower than a predetermined temperature range with respect to the ambient temperature, the refrigeration compressor (1)
The rotational speed of 6c) is lowered by frequency conversion to reduce the cooling capacity. Conversely, if it is high, the rotational speed of the refrigeration compressor (16c) is increased to increase the cooling capacity.

Now, when the temperature of the machining fluid (3) changes by (@°C) after a certain time (1), the heat exchange relationship is expressed by the following equation.

v-r-CP・θ=Q, -t-Qc-t=
Q, ・t-(Q, +K・θ)t ... [1] Where, V: Total volume of fluid (ze) r: Specific gravity (kg/m") Cp: Specific heat
(KeaJ / kg@c) K: Cooling capacity coefficient (
Kcal/'C) Ql: Calorific value (Kcal) Q,: Initial cooling heat amount (Kcal) When the above equation [1] is solved as a differential equation with respect to each variable t and θ, it is expressed by the following equation [2]. (initial condition t=o
, θ=00).

Based on the above equation [2], calculate how much cooling power area is required for the changing area of machining fluid heat amount, and apply this calculation result to control (not shown). The solenoid valve (16r) and the throttle (1
A plurality of solenoid valves (16f) of the opening/closing means are provided in order to respond to transient increases and decreases in the heat amount of the machining fluid according to commands from the control device. ) in stages. That is, when the amount of heat of the machining fluid increases transiently, the number of solenoid valves (16f) corresponding to the degree of increase are opened to increase the flow rate of the circulating refrigerant gas to increase the amount of cooling heat. On the contrary, when the heat amount of the machining fluid decreases transiently, the number of solenoid valves (16f) corresponding to the degree of decrease are closed, and the transient temperature fluctuation of the machining fluid temperature is reduced in each case. suppress about.

In the above embodiment, a machining fluid cooling device in a wire electrical discharge machining device was explained, but if it is a device that performs machining by supplying machining fluid between a machining means and a workpiece in a general machining device, The same effects as in the above embodiment are achieved.

〔Effect of the invention〕

As explained above, the present invention is to compare the temperatures detected by the ambient temperature detection sensor and the machining fluid temperature detection sensor of the machining device in a machining device that performs machining while supplying machining fluid. As a result, the temperature of the machining fluid supplied is continuously controlled, and the cooling capacity for the machining fluid is controlled in multiple stages in response to transient fluctuations in the machining fluid temperature. This has the effect of continuously uniformizing thermal deformation with the mechanical structure and allowing highly accurate processing to be performed without being affected by ambient temperature.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a machining fluid cooling device in a wire electrical discharge machining apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing details of the frequency conversion unit in FIG. 1, and FIG. 3 is a diagram showing a conventional wire electrical discharge machine. FIG. 1 is a configuration diagram showing an example of a processing device. In the figure, (1) is the workpiece, (3) is the machining fluid, αe
(16f) is a cooling device, (16f) is a solenoid valve, (IQ is a sensor for detecting processing fluid temperature, and α is a sensor for detecting ambient temperature. In addition, the same symbols in the figure indicate the same or equivalent parts.

Claims (2)

[Claims] (1) In a processing device configured to supply a cooling liquid to a gap between a workpiece and a processing means for processing the workpiece, a sensor for detecting the temperature of the processing liquid near the gap and the surroundings of the processing device a temperature detection sensor, a means for comparing the outputs of these sensors and continuously controlling the temperature difference so that it is within a predetermined temperature range, and a means for continuously controlling the temperature difference so that the temperature difference is within a predetermined temperature range; 1. A machining fluid cooling device characterized by comprising: a means for controlling a machining fluid temperature by switching a cooling capacity to a temperature of the machining fluid; (2) The machining fluid cooling device according to claim 1, wherein the machining device is a wire electrical discharge machining device.