JPH0220366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The disclosed technology belongs to a technical field in which hardening is performed at the same position after main machining is performed by electrical discharge machining or the like.

Therefore, the present invention performs forming processing into a predetermined shape on a workpiece for mold production by main processing such as die engraving or drilling electrical discharge machining, wire cut electrical discharge machining, or milling using a ball-end middle tool or the like. After that, the outer periphery of the molded part is further quenched to harden mainly the surface surface and/or inner periphery of the outer periphery of the workpiece molded part. It is an invention related to, in particular, relative movement between the main processing tool and the workpiece setting device by an NC-controlled movement mechanism that can perform servo control as necessary to move the workpiece set in a workpiece setting device using a main processing tool. A predetermined main machining is performed by the machining movement, and then, with the workpiece still set, the operation of the main processing tool can be arranged concentrically with the axis of the main processing tool using a switching device. Alternatively, the workpiece is formed by switching to a local hardening device that is provided concentrically with the main processing tool so that it can be alternately set and withdrawn, and the local hardening device, for example, uses plasma and a coolant to continuously form the workpiece. This invention relates to a mold processing method in which local hardening is performed using a plasma jet or the like while the surface and/or inner peripheral surface of the outer periphery of the processing portion is controlled and moved by the NC control movement mechanism.

[Conventional technology]

As is well-known, in various industrial products, for example, press molds, etc. are hardened by hardening the entirety of each of the punch and die, or at least the respective engaging edges, after machining with a milling cutter, etc., to prevent engagement wear. , and furthermore to prevent damage.

However, if the workpiece is subjected to heat treatment such as quenching after main processing such as drilling or die engraving, it often causes distortion and requires correction and reprocessing.
There has been a demand for a method that reduces the occurrence of such distortion, for example, by performing partial or local heat treatment on desired edge portions.

In addition, electrical machining such as electrical discharge machining is advantageous because it allows drilling, engraving, etc. to be performed on a predetermined hardened workpiece, but the outer edge of the forming process is tempered by the electrical machining action. Therefore, there is a need to easily perform heat treatment such as partial or local hardening on the edge portion.

The processing step involves forming the workpiece into a predetermined shape by main processing such as electric discharge machining or milling, and then heat treatment such as hardening in the next step, for example, hardening the outer peripheral edge part of the forming process. A two-step process is required.

[Problem that the invention seeks to solve]

Therefore, in general, in the hardening process, after the workpiece has been formed by the main processing, it is removed from the workpiece setting device of the main processing device such as electric discharge machining, and is set again in the local control hardening device for the edge portion of the next process. A predetermined locally controlled hardening process is performed.

Therefore, as a matter of course, when transferring the workpiece from this processing device to the local control hardening device and resetting it, the reproducibility of positioning the workpiece is poor, and it is necessary to selectively move a predetermined edge portion or edge portion only to a predetermined width. There were drawbacks such as the inability to locally control hardening.

Therefore, even if expensive automatic control means are introduced for local hardening of edges, etc., there are drawbacks such as the need for skill in work setting and the need for cumbersome processing control even during hardening work. However, there were disadvantages such as poor work efficiency and low machining accuracy.

Furthermore, it was necessary to install two types of automatically controlled expensive main processing equipment and local hardening equipment.
This has the disadvantage that it occupies a large amount of space and increases the cost of the product due to equipment investment.

The purpose of this invention is to solve the various problems associated with performing forming and hardening in two separate processes based on the above-mentioned conventional technology, and to solve the problems that arise when forming and hardening are performed in two separate processes based on the above-mentioned conventional technology. The above-mentioned problem is solved by providing a hardening jig device except for parts common to the processing device, which can be set and retracted alternately with the forming tool device,
The object of the present invention is to provide an excellent mold processing method that is useful in the field of precision processing technology application in the mechanical industry, by allowing the quenching process to continue with the workpiece set in the processing device. .

[Means and actions for solving problems]

In order to solve the above-mentioned problems, the configuration of the present invention, which is based on the above-mentioned claims and in accordance with the above-mentioned object, is to set a workpiece in the workpiece setting device of the present processing device, and to set the workpiece in the workpiece setting device installed in the present processing device. The tool is operated, the servo movement mechanism is driven by NC (numerical) control according to a preprogrammed program, and the workpiece setting device and the main processing tool are moved relative to each other to perform a predetermined forming process, and After the forming process is completed, a switching device is used to switch the operation from the main processing tool to a local hardening device that is provided concentrically with the axis of the processing tool or replaceably concentrically, and the work set is With the workpiece still set in the device, the servo moving mechanism is driven again according to the program, and the surface and/or inner peripheral surface of the outer periphery of the processed cavity or hole of the workpiece is heated in the hardening device. This method takes technical measures such as subsequent hardening using, for example, plasma.

〔Example〕

Next, one embodiment of the present invention will be described below based on the drawings.

Reference numeral 1 denotes a processing device that constitutes the gist of the present invention, and in the illustrated embodiment, it performs numerically controlled wire cut electrical discharge machining of a die for press molding, and then performs processing such as cutting by wire cut electrical discharge machining on the outer periphery of the forming process. This is a hardening process.

In the processing apparatus 1, a workpiece setting apparatus 3 is placed on a base frame 2 installed on the base, and a stand 4 is erected from the base frame 2. 5. A quenching device 6 is installed, and a drain funnel 7 provided below both devices 5 and 6 is connected to a tub 8.
, and extends from the stand 4.

As shown in FIG. 2, in the work setting device 3, the X-axis displacement table 10 linked to the X-axis motor 9 and the Y-axis displacement table 12 linked to the Y-axis motor 11 are engaged, and the It is installed on a bed 13 fixed to the base frame 2 so as to be able to slide orthogonally, and both motors 9 and 11 are connected to an NC unit 14 to form a digital servo movement mechanism 14'. are doing.

Further, a workpiece 16 of a mold die is held by a chuck 17 on the upper surface of a table 15 fixed to the Y-axis displacement table 12.

On the other hand, in the main processing device 5, a U-shaped frame 19 having upper and lower arms 20 and 21 facing each other in the Z-axis direction is held on the stand 4 via a Z-axis sliding bearing 18. , Z of the frame 19
The axial position is adjusted and set by a motor 23.

Reference numerals 27 and 28 denote a pair of positioning die guides which are disposed at the tips of the arms 20 and 21 to face each other in the Z-axis direction, and guide and position the wire electrode 38 as a tool for main processing. In this step, a wire cut electrical discharge machining section for the main machining is formed.

The wire electrode 38 is unwound from the storage drum 25 provided within the frame 19 or on the stand 4, and with the unwinding being braked by the tensioning brake roller 31, the wire electrode 38 is moved to the guides 27, 28 by the unwinding capstan and the pinch roller 32. The winding drum 26 is moved under tension between the winding drums 26 and 26 to be wound up by the other winding drum 26.

24 and 30 are guide rollers, and 29 is an energizing roller that connects a wire electrode to one terminal of a power source for wire cut electric discharge machining as the main processing, and the power source is a DC power source 40, and the voltage of the DC power source 40 is turned on.
It is provided with an electronic switching element 39 which is controlled to be turned on and off by the off-time control device 22, or, if necessary, a charging/discharging capacitor (not shown), the other terminal of which is connected to the workpiece 16.

In the case of the embodiment shown in Figs. 1 to 3, 6 also serves as a plasma discharge nozzle for quenching heat treatment as described later, but in wire cut electric discharge machining as the main machining, machining fluid, usually a predetermined resistivity If necessary, use a machining liquid injection nozzle that sprays water close to pure water.
It is also provided at the bottom of 6.

The wire electrode 38 inserted into the pre-machined hole 16' of the workpiece 16 is wound up and moved at a predetermined speed, preferably without causing large wobbling, and the machining liquid is supplied from the nozzle 6 to the pre-machined hole 1.
6' The machining fluid is injected into the machining portion of the prepared hole 16', and the control device 22 is operated to apply intermittent voltage pulses between the workpiece 16 and the wire electrode 38, and the NC device 14 The motors 9 and 11 are operated according to a predetermined set program to move the workpiece 16 at a predetermined constant speed in a horizontal plane perpendicular to the axis of the wire electrode 38, or between the wire electrode 38 and the workpiece 16.
When feed is applied by servo control that maintains the voltage between the two at a predetermined constant value, the workpiece 16 is processed in the manner of cutting with a jig saw, and therefore the program is controlled to give the workpiece 16 a processing feed of a predetermined contour shape. Then, the predetermined shape is formed or cut out.

The cut side surface of the forming process has a machined surface roughness determined by the electric discharge machining conditions of wire cut electric discharge machining, mainly the machining voltage pulse conditions.

In addition, 33 is a switching control device for wire cut electric discharge machining 5 and quenching heat treatment machining 6, which will be described later.
Also performs operation switching, etc. The hardening device 6, which also serves as the machining fluid injection nozzle, is rotated or moved by an elbow block 41 bored from the stand 4, and is interposed concentrically with the axis of the machining part of the wire electrode 38, and Although it is provided so as to be able to control retraction to a predetermined side, when it is also used as a machining fluid spray nozzle as described above, a wire electrode 38 is set concentrically through the device 6 as shown in the figure.

That is, in the case of complete concentricity, the wire electrode 38 passes through the axial hole of the center electrode rod 42, such as a cathode, as shown in FIG. The casing 43 is provided with a plasma discharge forming gas introduction port 44 and a ring-shaped anode nozzle 45 having a plasma discharge injection hole at its tip.

The cathode rod 42 and the anode nozzle 45 are connected to a resistor 46 and a wire cut discharge via a plasma power control device 35 controlled by a plasma and machining fluid control device 34 switched by the switching control device 33. The machining power sources 22, 39, and 40 are connected to a power source 47, which may be used in combination, to form or stop plasma discharge between them.

50 and 51 are concentric around the anode nozzle 45;
and a ring-shaped nozzle jacket that forms a water nozzle for plasma cooling and hardening, and for spraying machining fluid during wire cut electrical discharge machining; 49 is a jetting fluid rectifying plate provided between the anode nozzle 45; , the nozzle jackets 50, 51
The two ports are provided with electromagnetic valves 52 and 52 respectively controlled by the plasma and processing fluid control device 34.
53, tank 5 with feeding pumps 54 and 55 interposed
6, 57 are connected, and the tanks 56, 57
For example, at least one of the tanks 56 is filled with liquid 58 for wire cut electrical discharge machining, and the other tank 5
A cooling liquid for quenching or water 59, which is the same as the tank 56, is stored in each of the tanks 7 and 7, respectively.

On the other hand, a liquefied titanium cylinder 62 and a liquefied argon cylinder 63 are connected to a passage 60 connected to the port 44 via an electromagnetic valve 61 controlled by a plasma and machining fluid control device 34 through a check valve 60.
4 and 65 in parallel.

A fixed or adjustable throttle valve 66 is interposed between the argon cylinder 63 and the check valve 65 so that the flow rate ratio of the two cylinders 62 and 63 is an appropriate ratio such as 2:1. has been adjusted to.

Furthermore, the electromagnetic valves 52, 53, and 61 are connected to the control device 34, and are provided so as to be able to be controlled to open and close according to purposes such as a predetermined program.

Reference numeral 67 is the wire-cut electric discharge machining cut surface of the workpiece 16, which has a slightly uneven pear surface according to the machining conditions, 67a is the inner peripheral surface of the outer periphery of the forming process, and 72b is the surface surface of the outer periphery. These are the parts that will become the edges of the mold.

In the above configuration, when operating the main processing device 5 of the processing device 1 to form the workpiece 16, first, the control devices 33 and 34 supply a voltage pulse to the wire electrode 38, and the plasma electrode 42,
45 is stopped, the electromagnetic valves 53 and 61 are closed, the electromagnetic valve 52 is opened, and the capstan and the pinch roller 32 are driven to start and maintain the renewed supply of the wire electrode 38 to the processing section at a predetermined tension state. At the same time, pre-programmed NC
The unit 14 is connected to the X-axis motor 9 and the Y-axis motor 1.
1 is driven in a predetermined manner to cause the X-axis displacement table 10 and the Y-axis displacement table 12 to move in the XY direction.

Then, intermittent electric discharge occurs between the wire electrode 38 and the machining fluid, and as described above, the wire cut electric discharge machining progresses, and the workpiece 16 is machined and cut into a predetermined shape, or Forming a mold die by cutting out.

Therefore, by performing the above-mentioned process or further finishing wire cut electric discharge machining in wire cut electric discharge machining such as a second cut, the workpiece 1 is
When the mold forming process in step 6 is completed, the capstan 32 is stopped via the switching control device 33 by switching settings such as manual or program, the winding and renewal feeding of the wire electrode 38 is stopped, and the power source 40,
The pulse energization by the switching element 39 is cut off, and the control device 34 closes the electromagnetic valve 52, and further closes the electromagnetic valve 53, 61.
At the same time, the power supply control device 35 makes the power supply 47 energized and switches the operation to the hardening device 6.

Then, a wire electrode 38 as a tool for main processing
Although a heat-resistant material such as tungsten is sometimes used, it is usually made of copper or a copper-zinc alloy.
Guide 2 because it has no heat resistance and is a nuisance.
The guide 28 is cut near the exit of the guide 7, and the cut end is removed until it reaches at least the tip of the other guide 28.

In addition, if the hardening device 6 does not also serve as a machining fluid nozzle, the device 6, which had been retracted to the side of the axial center of the wire electrode 38, is moved to the control device 3 at this stage.
3, the elbow block 41 is rotated to set the device 6 in the illustrated position.

After the above-mentioned switching is completed, the start button is pressed and the processing device 1 is operated again, and the quenching device 6 is activated, and the outer periphery of the machined hole formed in the workpiece 16 by wire cut electrical discharge machining as the main processing. Edge portion 67b of the surface layer of the peripheral portion
And/or the edge portion 67a of the inner circumferential surface is heated by discharge plasma injection and cooling quenching is performed by cooling water injection, sequentially progressing along the outer periphery of the main processing shape of the edge portions 67a, 67b. It will be done.

That is, in the casing 43, the liquefied nitrogen gas and argon gas from the liquefied nitrogen cylinder 62 and the liquefied argon cylinder 63 pass through the passage 60 and are ejected and supplied from the port 44 by a fixed throttle valve at a flow rate ratio of, for example, 2:1. The power source 47 is energized, a discharge arc is formed between the cathode rod 42 and the anode nozzle 45, the nitrogen gas and argon gas are heated and ionized, and a plasma discharge arc is ejected from the anode nozzle 45 to form the outer periphery of the machined hole. After heating the edge part 67b on the surface surface and/or the edge part 67a on the inner circumferential surface of the part, the temperature is rapidly lowered by exposing it to the jet of the cooling water 59, and quenching is performed.

Of course, during this time the X, Y displacement tables 10, 1
2 is performed by adding offset correction of a predetermined minute dimension to the same program as that for the forming process of the main processing and processing of the outer periphery of the shape in the above-mentioned quenching operation, or by adjusting the quenching process speed by adjusting the capacity of the device 6, etc. Set the correction according to the
As a result, the X and Y axis motors 9 and 11 are operated in a predetermined manner to relative slide, and the outer periphery shape of the forming shape during the wire cut electric discharge machining as the main machining of the workpiece 16 is tracked and scanned with respect to the anode nozzle 45. Restore accurately. The hardening ability of the hardening device 6 can be of various degrees, but for example, for a mold material such as SK11, the hardening capacity can be approximately 1 to 2 mm in width and about 2 mm deep from the edge of the outer peripheral edge toward the surface layer and/or inner peripheral surface. It is thought that about 0.5 to 1 mm is required, but for this degree of hardening treatment, the machining power supply for wire cut electric discharge machining, for example, the normal voltage of about
Pulsing of around 100 to 300 V and current of around 10 A, or a pre-pulsed DC power supply can be used as is.

That is, for example, if the power supply is 200V and 10A,
In order to heat and harden the edge portion with the above width and depth, even if the heating efficiency is about 30%, the hardening processing speed, that is, the relative shape scanning of the hardening processing between the nozzle 45 and the workpiece 16. Increase movement speed to about 150
This means that there is a heating capacity that can be considered moderate in mm/min, which corresponds to the machining speed of wire cut electrical discharge machining, approximately
It can be seen that the speed can be sufficiently covered from 0.5 to 60 mm/min.

Most importantly, if the power supply capacity is insufficient, it is sufficient to install it in advance, and there is no particular problem.

However, it is impossible to generate a plasma arc between the electrodes 42 and 45 by using a power source for electrical discharge machining of about 200V.
An active electrode such as a 1.6 to 2 mm/φ thorium-containing tungsten electrode or a rare-earth metal element-containing copper electrode is used, and a heat-resistant electrode is used as the electrode 45. This is because a high voltage of at least about 2 KV or more is required to generate a discharge to generate a plasma arc between the electrodes.

The embodiment shown in FIG. 4 shows a power supply as an example of a countermeasure for such a case, and 68 is for electrical discharge machining;
Alternatively, it is a DC power supply for wire cut electrical discharge machining, or a pulse power supply, and 69 is an output terminal as a power supply for electrical discharge machining. When the power supply 68 is a DC power supply, a pulse generation circuit is provided on the output side of the terminal 69.

Note that the power source 68 may have a current capacity increased to approximately 20 A (average).

70 is the output to the electrodes 42 and 45 and the power source 68
A high voltage surge prevention circuit 71 such as a reactance filter and a rectifier is connected between the power source 68 and the power source 68.
will be provided.

72 is a plasma start control switch provided between the high voltage power source 70, and 73 is a plasma start control switch provided between the power source 70 and the high voltage power source 70;
A safety switch is provided as necessary between the switch 72 and the power supply 68, and is closed after a short delay time after the switch 72 is closed.

74 is a controller for the power supply 68, high voltage power supply 70, and switches 72 and 73.

In the illustrated embodiment, as the high voltage power supply 70,
This is a case where a high-voltage discharge power supply consisting of a high-voltage DC power supply 70a and a discharge capacitor 70b charged by the power supply 70a is used, but it is also possible to generate plasma by high-frequency discharge using a high-voltage high-frequency power supply. good.

In the case of the illustrated circuit, the switches 72 and 73 are opened, charging of the capacitor 70b to a predetermined voltage is stopped by the high-voltage DC power supply 70a according to a command from the controller 74, and the switch 72 is closed and the capacitor 70b is charged to a predetermined voltage by the controller 74. When the capacitor 70b discharges, the controller 74 turns on the switch 73.
Close and generate a plasma arc.

36 is a capacitor 70b between electrodes 42 and 45.
When a high voltage discharge occurs, a heater that heats the gas flowing between the electrodes 42 and 45 and the argon mixed gas so that a plasma arc is easily generated,
In this case, it is provided within the torch 43, and 37
is a heating power source for the heater 36, and the control device 34
Accordingly, the heating is controlled to a predetermined level only at least when the plasma arc starts to be generated.

It goes without saying that the embodiment of the present invention is not limited to the above-mentioned embodiment. For example, this machining is not limited to the case of wire cut electric discharge, but also tertiary machining by NC control using a die-sinking electric discharge machine. When performing die engraving of the original shape, that is, when forming a hole or cavity by NC 3-axis control using a simple shaped electrode such as a rod, or when forming a hole or cavity using a die electrode, NC control is performed. It can also be carried out when processing is performed according to the external shape, or when a hole or cavity is formed by NC milling using a ball end mill tool, etc. on a milling machine, etc., or when local heating is performed. As a means of heating, it is also possible to use laser heating instead of plasma arc.

〔Effect of the invention〕

As described above, according to the present invention, in the mold processing method, the workpiece is basically clamped in a predetermined position by the same processing device, from the main processing to the post-processing quenching. Processing can be done in a series of operations, and since virtually the same control program is used, there is no need to remove, reset, or replace the workpiece, improving work efficiency. The reproducibility of the machining position of the workpiece during machining is good, the accuracy is significantly improved, and excellent effects are achieved in that no skill is required.

Furthermore, since the forming process and the hardening process are performed in one processing device, the equipment cost is reduced and the occupied space is reduced, so that the cost of the product can be significantly reduced.

Furthermore, since the steps from forming to hardening are performed in series by a switching device, there is the advantage that work can be taken over smoothly.

In addition, the local heating means of the hardening device is configured so that it can be arranged concentrically with the tool for main processing, and during the hardening process, the local heating means is adjusted to the shape of the forming process using the NC program used during the forming process. By relatively moving the mold along the outer peripheral edge, it is possible to locally accurately and easily harden the outer peripheral edge of the mold after molding.

[Brief explanation of drawings]

The drawings show one embodiment of the invention,
Fig. 1 is a schematic side view of the embodiment, Fig. 2 is a partially enlarged schematic sectional view of Fig. 1, Fig. 3 is an enlarged schematic sectional view of the portion 6 in Fig. 2, and Fig. 4 is a power supply circuit diagram. be. 1... Processing device, 3... Work setting device, 5
... main processing device, 6 ... processing liquid injection nozzle and quenching device, 16 ... workpiece, 33, 34 ... switching device, 38 ... main processing tool, 45 ... plasma injection nozzle.

Claims (1)

[Claims] 1. In a mold processing method in which the outer periphery of the molding process is hardened after performing the prescribed forming process of the main process on the workpiece for mold production,
A local heating means is provided so that it can be arranged concentrically with the axis of the main machining tool, and a program related to the machining shape preprogrammed in the numerical control device is installed between the workpiece set in the work setting device and the main machining tool. After performing the molding process into a predetermined mold shape by relative movement, the workpiece is set in the workpiece setting device, and there is a gap between the local heating means and the workpiece during the molding process. The outer periphery of the forming process is heated and quenched by relatively moving along the outer periphery of the forming process using the program related to the processed shape used. Characteristic mold processing method.