JP2010115757A - Wire-cut electric discharge machine having discharging liquid temperature control function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire-cut electric discharge machine for solving a problem at a low cost and having a temperature control function to maintain a discharging liquid temperature in a discharging tank equal under various discharging conditions. <P>SOLUTION: A wire-cut electric discharging apparatus having a discharging tank 2, a holding tank 3 for retrieving or storing the discharging liquid from or in the discharging tank 2, a freshwater tank 4 for storing the discharging liquid in the holding tank 3 via a filter F, discharging liquid supply routes (L1a and L1b) for supplying the discharging liquid from the freshwater tank 4 to the discharging tank 2, and supply routes (L2a and L2b) for supplying the discharging liquid from the freshwater tank 4 to an upper/lower wire guide 5, includes a discharging liquid cooling device 6 to cool the discharging liquid in the freshwater tank 4 and supply it to the freshwater tank 4 and a control device 10 being a temperature control means to control the setting temperature of the discharging liquid cooling device 6 for rough machining to be lower by a predetermined temperature than the setting temperature for finish machining. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wire cut electric discharge machine, and particularly has a feature in temperature control of a machining fluid.

The wire electric discharge machine applies a voltage between a wire electrode and a workpiece to generate a discharge to process the workpiece. A machining fluid is interposed between the wire electrode and the workpiece in order to insulate between the wire electrode and the workpiece, to remove machining waste generated by cooling and discharging. This machining fluid is heated by the electric discharge between the wire electrode and the workpiece, and the temperature rises. Further, the temperature rises due to heat loss of a pump that supplies the machining fluid to a machining tank or the like in which the workpiece is arranged.
The workpiece and the table on which the workpiece is placed are deformed by thermal expansion due to the temperature rise of the machining fluid, which causes a reduction in machining accuracy and a breakage of the wire electrode. For this reason, the wire electric discharge machine is provided with a cooling device for cooling the machining fluid.

  During processing, depending on the processing conditions, the water temperature of the processing tank for storing the workpiece becomes higher than the water temperature of the cooling device or the fresh water tank controlled by the processing and heat generated by the pump. In a normal case, the temperature of the water cooled by the cooling device and the temperature of the water in the fresh water tank are controlled so as to become set temperatures. Therefore, the water temperature of the outlet of the cooling device or the fresh water tank is controlled to a constant temperature even when there is a change in the amount of heat, such as roughing and finishing.

  However, the water temperature in the processing tank is circulated by supplying water from the fresh water tank or the water outlet of the cooling device, but heat is generated by the operation of the jet flow rate pump and electric discharge machining while machining the workpiece. However, a very large amount of heat is generated during roughing. On the other hand, almost no heat is generated during finishing. As shown in FIG. 9, the water temperature in the processing tank at the time of rough machining is compared with the water temperature in the processing tank at the time of finishing as “temperature difference ΔTem *”. "It will be high.

In Patent Document 1, in order to eliminate the above-described temperature difference “temperature difference ΔTem *”, the processing liquid temperature in the processing tank can be kept uniform even if the processing state changes with finishing, etc. during rough processing. A wire electric discharge machine is disclosed.
FIG. 10 is a diagram showing a wire electric discharge machine disclosed in Patent Document 1. In FIG. A first temperature sensor S <b> 1 for detecting the processing liquid temperature in the fresh water tank 4 is provided in the fresh water tank or the processing liquid cooling device 6. A second temperature sensor S <b> 2 for detecting the processing liquid temperature in the processing tank 2 is provided in the processing tank 2. The control device 10 of the wire electric discharge machine selects the second temperature sensor for processing with a large amount of heat generation such as roughing, and selects the first temperature sensor S1 for processing with a small amount of heat generation such as finishing. . The machining liquid cooling device 6 controls cooling of the machining liquid in the fresh water tank 4 based on the temperature detected by the selected temperature sensor. Even if the machining state changes, the machining liquid temperature in the machining tank 2 can be maintained uniformly at a temperature close to the target control temperature. This temperature control technique requires the use of two temperature sensors.

  Patent Document 2 discloses an electric discharge machining apparatus that detects a machining speed in order to control the temperature of a machining liquid supplied to a machining gap in accordance with a Z-axis feed speed during machining. Patent Document 3 discloses an electric discharge machining device that detects an average machining current and a machining fluid flow rate and controls the cooling capacity of the cooling device based on the detection result.

JP 2007-319943 A Japanese Patent Laid-Open No. 2-185322 JP-A-1-321120

  Since the technology described in the background art is feedback control based on the temperature detected by the temperature sensor, the control is performed after sensing the rise in the water temperature, and it is difficult to perform temperature control with better response. Moreover, a temperature sensor is required in two places, a processing tank and a fresh water tank, and it causes a cost increase. The technology for detecting the processing speed, processing current, and processing flow rate requires the use of each detection sensor, which complicates the configuration of the apparatus and increases costs.

  Accordingly, an object of the present invention is to provide a wire-cut electric discharge machine having a temperature control function that solves the above-mentioned problems with an inexpensive configuration and maintains the machining liquid temperature in the machining tank uniformly with respect to various machining conditions. That is.

  The invention according to claim 1 of the present application includes: a processing tank; a sewage tank that collects and stores the processing liquid in the processing tank; a fresh water tank that stores the processing liquid in the sewage tank through a filter; In the wire-cut electric discharge machine having a first machining liquid supply path for supplying a machining liquid to the machining tank and a second machining liquid supply path for supplying the machining liquid in the fresh water tank to the upper and lower wire guides, the fresh water tank And a control means for controlling the cooling temperature of the processing liquid cooling device, and the control means sets the set temperature during rough processing during finishing processing. A wire-cut electric discharge machine having a machining liquid temperature control function, wherein the machining liquid cooling device is controlled to be lower than the set temperature by a predetermined temperature according to machining conditions.

  The invention which concerns on Claim 2 is a processing tank, the sewage tank which collect | recovers and stores the processing liquid of this processing tank, the fresh water tank which stores the processing liquid of this sewage tank through a filter, and the processing liquid of the said fresh water tank In a wire-cut electric discharge machine having a second machining fluid supply path for supplying the machining fluid to the upper and lower wire guides, a machining fluid cooling device that cools the machining fluid in the fresh water tank and supplies it to the machining tank, and the machining fluid cooling device Control means for controlling the cooling temperature of the machining fluid, wherein the control means controls the machining fluid cooling device to lower the set temperature at the time of rough machining to a predetermined temperature lower than the set temperature at the time of finish machining according to the machining conditions. It is a wire cut electric discharge machine having a machining fluid temperature control function.

The invention according to claim 3 is provided with a temperature setting means, and the predetermined temperature is preset by the temperature setting means, and the machining fluid temperature control according to any one of claims 1 and 2 This is a wire cut electric discharge machine having a function.
The invention according to claim 4 includes setting temperature storage means for storing the setting temperature at the time of roughing and the setting temperature at the time of finishing machining for each processing condition, and the control means stores the temperature stored in the setting temperature storage means. The cooling temperature of the machining fluid cooling device is controlled based on the information, and the temperature of the machining fluid in the fresh water tank is lowered by the predetermined temperature according to the machining conditions during the rough machining than in the finish machining. This is a wire-cut electric discharge machine having a machining fluid temperature control function described in any one of the above.

  According to the present invention, the processing liquid temperature in the processing tank can be uniformly controlled in roughing and finishing even if the processing conditions change with an inexpensive configuration. Thereby, the deformation | transformation of the table which mounts the workpiece and workpiece which generate | occur | produce by the temperature change of a process liquid can be suppressed, a machining precision can be improved and the wire cut electric discharge machine which can suppress the disconnection of a wire electrode can be provided.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram of a processing liquid process according to an embodiment of the present invention. In addition, the same code | symbol is used for the element same as a prior art. A machining tank 2 is provided in the mechanism section 1 of the wire electric discharge machine, and an electric discharge machining section is provided in the machining tank 2. A workpiece, which is a workpiece, is placed on and attached to a table provided in the mechanism unit 1. A voltage is applied between the workpiece and a wire electrode (not shown) to generate a discharge while generating a discharge. EDM is performed on the workpiece by relatively moving the workpiece.

  The processing tank 2 is supplied with a processing liquid and stored therein. The machining fluid in the machining tank 2 is mixed with machining scraps generated by electric discharge, and this machining liquid is configured to flow out into the sewage tank 3 as indicated by reference numeral 7. The processing liquid collected and stored in the sewage tank 3 is pumped up by the filter pump P1, passed through the filter F, filtered, and processed waste is removed and supplied to the fresh water tank 4.

  The machining liquid stored in the fresh water tank 4 is pumped up by the circulation pump P3 through the machining liquid supply path L1a, branched at the discharge port, and one is supplied to the machining tank 2 through the machining liquid supply path L1b. The other is supplied to the machining liquid cooling device 6, cooled, and returned to the fresh water tank 4 via the machining liquid return path L1c.

The fresh water tank 4 is provided with a temperature sensor S as temperature detection means for detecting the temperature of the machining liquid. Alternatively, a temperature detecting means is provided in the machining liquid cooling device 6 so as to measure the temperature of the machining liquid in the fresh water tank 4 or the temperature of the machining liquid pumped from the fresh water tank 4 and sent to the machining liquid cooling device 6. May be.
The machining fluid cooling device 6 receives a command signal from the control device 10 of the wire electric discharge machine, cools the machining fluid based on the machining fluid temperature detected by the temperature sensor S, and performs machining via the machining fluid feedback path L1c. Return the liquid to the fresh water tank 4.

  The jet pump P2 pumps up the machining liquid stored in the fresh water tank 4 through the machining liquid supply path L2a and supplies it to the upper and lower wire guides 5 through the machining liquid supply path L2b. The upper and lower wire guides 5 jet the machining liquid from the nozzles provided on the upper and lower wire guides toward the gap between the wire electrode and the workpiece, cool the gap, and remove machining waste generated by the discharge from the gap. To do.

The present invention controls the cooling of the machining liquid by the machining liquid cooling device 6 so that the temperature of the machining liquid supplied to the machining tank is lower by a predetermined temperature in accordance with the machining conditions at the time of rough machining than at the time of finish machining. It has the characteristics.
In this way, the temperature of the machining fluid is controlled, the temperature of the machining fluid at the time of rough machining is lowered in advance than at the time of finishing machining, and the machining fluid heated by the heat loss of the circulation pump P3 or the jet pump P2 is heated. Due to the temperature rise caused by the heat generated by the electric discharge machining, the temperature in the machining bath 2 becomes uniform during roughing and finishing.

  FIG. 2 is a block diagram of the main part of the control device for the wire electric discharge machine in one embodiment of the present invention for controlling the temperature of the machining fluid. The control device 10 composed of a numerical control device or the like includes a processor 11 and a memory 12 composed of ROM, RAM, etc., connected to the processor 11 via a bus 18, an indicator 13, an input means 14 such as a keyboard, It comprises an interface 15 for inputting or outputting a machining program or the like from an external storage medium, each axis control means 16, an input / output circuit 17, and the like.

  Each axis control means 16 moves the table on which the workpiece is placed in the X and Y axis directions orthogonal to each other, and moves the upper guide in the direction orthogonal to the X axis and Y axis. Controls each motor that drives the orthogonal U-axis and V-axis for taper machining, and includes feedback control means for the position, speed, and current of each axis. Each axis control means 16 is connected to each axis servo motor 25 via a servo amplifier 21 for each axis. Each servomotor is provided with a position / speed detector and is configured to feed back the position and speed to the respective axis control circuits, but is not shown in FIG.

  The input / output circuit 17 is connected to a power supply circuit 22, a machining fluid cooling device 6, and a temperature sensor S for applying a voltage between the wire and the workpiece of the wire electric discharge machine to cause discharge. The detected temperature from the temperature sensor S is converted to a digital signal by an A / D converter (analog / digital converter) provided in the input / output circuit 17. The input / output circuit 17 is connected to other peripheral devices such as sensors and actuators.

  FIG. 3 is an example of changes in the water temperature in the processing tank when the temperature is lowered in advance only during roughing according to the present invention. The vertical axis of the graph shown in FIG. 3 is the temperature in the processing tank 2, and the horizontal axis represents time. A broken line represents a set temperature value for the machining liquid cooling device 6. The set temperature value at the time of rough machining commanded from the control device 10 to the machining fluid cooling device 6 is lowered by a predetermined temperature ΔTem from the set temperature value at the time of finishing machining, and the set temperature value is restored to the original value at the time of finishing machining. As shown in the figure, the temperature of the machining liquid in the machining tank 2 can be made uniform during rough machining and during finishing.

  Since the predetermined temperature ΔTem varies depending on the machining conditions, the operator may arbitrarily set it according to the machining conditions. In this case, the temperature to be set is input via the input means 14 and stored in the memory 12. Further, a predetermined temperature ΔTem suitable for the machining conditions may be collected as data in advance and stored in the memory 12 in the control device 10 of the wire cut electric discharge machine. The temperature data stored in the memory 12 may be stored as a predetermined temperature ΔTem, or may be stored as a set temperature value during rough machining and a set temperature value during finish machining.

  FIG. 4 is a diagram for explaining changing the predetermined temperature according to the processing conditions. The processing condition A shown in FIG. 4A is a processing condition in which the wire alignment of the wire electrode is 0.25 mm, the thickness of the workpiece as a workpiece is 60 mm, and the workpiece material is die steel (SKD11). (Roughing) 2nd cut (first finishing) and 3rd cutting (second finishing) are performed. In the machining condition A, in the first cut (rough machining), the set temperature of the machining liquid cooling device 6 is set to be 1 ° C. lower than the set temperatures of the 2nd cut and 3rd cut finishing, that is, the predetermined temperature ΔTem is set to −1 ° C. This means that temperature control is performed.

  The processing condition B shown in FIG. 4B is a processing condition in which the wire alignment of the wire electrode is 0.25 mm, the thickness of the workpiece as the workpiece is 50 mm, and the workpiece material is stainless steel (SUS304). (Roughing) 2nd cut (first finishing) and 3rd cutting (second finishing) are performed.

  In this processing condition B, the processing liquid cooling device 6 is controlled by a first cutting (roughing) roughing, and the set temperature is controlled by a predetermined temperature 0.7 ° C. lower than the setting temperatures of the 2nd and 3rd cutting finishing. is doing. The predetermined temperature of 0 ° C. in the finishing process indicates that there is no deviation from the set temperature of the machining liquid cooling device 6. In this case, the set temperature is a preset value.

  FIG. 5 is a diagram for explaining changing the set temperature according to the processing conditions. FIG. 5A is an example in which the setting of the predetermined temperature in FIG. 4A is stored as the set temperature. FIG. 5B is an example in which the setting of the predetermined temperature in FIG. 4B is stored as the set temperature.

  The processing temperature A and the processing condition B are different in the magnitude of the predetermined temperature that lowers the cooling temperature of the machining fluid cooling device 6 during rough machining. The value of the predetermined temperature for each machining condition is determined according to the actual machining of the workpiece under each machining condition, and the fluctuation of the temperature of the machining liquid in the machining tank 2 is eliminated during rough machining and finish machining. The value of the predetermined temperature is obtained. The obtained set temperature data is stored in advance in the memory 12 of the control device 10 together with the processing condition data.

  FIG. 6 is an example of an interface screen for an operator of the wire cut electric discharge machine to input a predetermined temperature. An example of the display screen of FIG. 6 is displayed on the display 13 (see FIG. 2), a predetermined temperature is input using the input means 14, and the input data of the predetermined temperature is stored in the memory 12.

  FIG. 7 is a flowchart showing an algorithm for controlling the machining fluid temperature executed by the processor of the control device 10 as an embodiment of the present invention. The temperature control process of the present invention is executed when a roughing command or a finishing command is read from the machining program. First, it is determined whether the read command is a roughing command or a finishing command (step ST1). ), If it is a roughing command, data of preset temperature for roughing stored in advance is read from the memory (step ST2), and the machining liquid cooling device 6 is commanded based on the read set temperature data (step ST3). ). On the other hand, if it is a finishing machining command, the preset temperature data of the finishing machining stored in advance is read (step ST4), and the machining liquid cooling device 6 is commanded based on the read set temperature data (step ST5). Note that it is possible to determine whether the command is a rough machining command or a finishing machining command by counting the number of machining operations.

  As described above, it is possible to execute the temperature control of the machining fluid cooling device corresponding to the roughing and finishing, and the machining fluid temperature in the machining tank 2 is maintained even if the machining state changes between roughing and finishing. Uniform temperature control.

FIG. 8 is a schematic block diagram of processing liquid processing according to another embodiment of the present invention. In this embodiment, the machining liquid cooled by the machining liquid cooling device 6 is supplied directly to the machining tank 2 via the machining liquid supply path L1d instead of the machining liquid supply path L1b shown in FIG. is there.
The machining liquid stored in the fresh water tank 4 is pumped up by the circulation pump P3 through the machining liquid supply path L1a and supplied to the machining liquid cooling device 6. The machining liquid is cooled by the machining liquid cooling device 6 and supplied to the machining tank 2 via the machining liquid supply path L1d. In this embodiment, the temperature sensor S is provided on the machining fluid discharge port side of the machining fluid cooling device 6 so as to measure the temperature of the machining fluid cooled by the machining fluid cooling device 6.

In the embodiment shown in FIG. 8, the cooled working fluid is not returned from the working fluid cooling device 6 to the fresh water tank 4, but may be returned to the fresh water tank 4 as shown in FIG. In this case, the temperature sensor may be disposed in the fresh water tank 4 as shown in FIG.
The remaining configuration is the same as that of the embodiment shown in FIG. Also in this embodiment, the temperature of the machining liquid in the machining tank 2 can be maintained uniformly during rough machining and finish machining.

It is a general | schematic block diagram of the process liquid process of one Embodiment of this invention. It is a principal part block diagram of the control apparatus of the wire cut electric discharge machine in one Embodiment of this invention. It is an example of the change of the water temperature in a processing tank at the time of lowering | hanging temperature previously only at the time of roughing by this invention. It is a figure explaining changing predetermined temperature according to processing conditions. It is a figure explaining changing preset temperature according to processing conditions. It is an example of the interface screen for the operator of a wire cut electric discharge machine to input predetermined temperature. It is a flowchart which shows the algorithm of the selection process of the temperature data to instruct | indicate. It is a general | schematic block diagram of the process liquid process of other embodiment of this invention. It is a figure which shows that the process liquid temperature in a processing tank fluctuates by roughing and finishing in the prior art. It is a principal part block diagram of the wire cut electric discharge machine which is a prior art using two temperature sensors.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mechanism part 2 Processing tank 3 Sewage tank 4 Fresh water tank 5 Upper and lower wire guide 6 Processing liquid cooling device 10 Control apparatus 11 Processor (CPU)
DESCRIPTION OF SYMBOLS 12 Memory 13 Display 14 Input means 15 Interface 16 Each axis control means 17 Input / output circuit 21 Amplifier 22 Power supply circuit P1 Filter pump P2 Jet pump P3 Circulation pump F Filter S Temperature sensor

Claims (4)

A processing tank, a sewage tank that collects and stores the processing liquid in the processing tank, a fresh water tank that stores the processing liquid in the sewage tank through a filter, and a first that supplies the processing liquid in the fresh water tank to the processing tank A wire-cut electric discharge machine having a machining liquid supply path and a second machining liquid supply path for supplying the machining liquid in the fresh water tank to the upper and lower wire guides.
A machining liquid cooling device for cooling the machining liquid in the fresh water tank and supplying it to the fresh water tank;
Control means for controlling the cooling temperature of the machining fluid cooling device,
The control means controls the machining liquid cooling device with a machining liquid temperature control function, wherein the machining liquid cooling device controls the machining liquid cooling device at a predetermined temperature lower than the set temperature at the time of finishing machining according to machining conditions. Machine. A processing tank, a sewage tank for collecting and storing the processing liquid in the processing tank, a fresh water tank for storing the processing liquid in the sewage tank through a filter, and supplying the processing liquid in the fresh water tank to the upper and lower wire guides. In a wire cut electric discharge machine having two machining fluid supply paths,
A machining fluid cooling device that cools the machining fluid in the fresh water tank and supplies it to the machining tank;
Control means for controlling the cooling temperature of the machining fluid cooling device,
The control means controls the machining liquid cooling device with a machining liquid temperature control function, wherein the machining liquid cooling device controls the machining liquid cooling device at a predetermined temperature lower than the set temperature at the time of finishing machining according to machining conditions. Machine. Temperature setting means,
The wire-cut electric discharge machine having a machining liquid temperature control function according to claim 1, wherein the predetermined temperature is preset by the temperature setting means. A set temperature storage means for storing a set temperature at the time of roughing and a set temperature at the time of finishing for each processing condition;
The control means controls the cooling temperature of the machining liquid cooling device based on the temperature information stored in the set temperature storage means, and the temperature of the machining liquid in the fresh water tank is determined according to the machining conditions from the finish machining during rough machining. The wire-cut electric discharge machine having a machining liquid temperature control function according to claim 1, wherein the temperature is lowered by a predetermined temperature.

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