JPS58160018A - Electric discharge device - Google Patents

Abstract

PURPOSE:To improve the precision of processing and the working efficiency by a method wherein the depth of a processing hole in a workpiece during processing is measured automatically and processing electrodes are fed into the processing hole section by a depth corresponding to the difference between the desired depth of the hole and the depth of the hole during processing. CONSTITUTION:The processing electrodes 10a and 10D are replaced with a measuring probe 32 before a processing hole 14 in a workpiece 12 reaches the desired depth and the depth of the processing hole 14 under processing is measured. Then the measuring probe 32 is replaced again by the processing electrodes 10a and 10b and the electrodes are fed to the processing hole section to correct the depth of the hole by a depth corresponding to the difference between the desired depth of the processing hole 14 and the depth of the processing hole 14 under processing so that the hole processing work is carried out automatically in one lot to thereby improve the precision of processing and the working efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric discharge machining apparatus, particularly an electric discharge machining apparatus that is equipped with an electrode feeding device that feeds a machining electrode toward a workpiece and forms a machined hole of a desired depth in the workpiece. Regarding.

Electrical discharge machining is a machining method in which a machining electrode and a workpiece are opposed to each other through a gap, and a discharge phenomenon is caused while supplying a machining liquid to the gap to machine the workpiece.

Conventionally, the apparatus described below has been used as an electric discharge machining apparatus for forming a machined hole of a desired depth in a workpiece.

That is, in FIG. 1, the processing electrode 10 is connected to the workpiece 1.
An electrode feeding device (not shown) is provided to continuously feed the electrode 10 toward the workpiece 12, and the processing electrode 10 is determined in accordance with the desired depth Zm of the processing hole 14 of the workpiece 12. A hole 14 with a desired depth Zm is formed in the workpiece 12 by the distance
was being formed.

Generally, the feed amount of the processing electrode 10 is
The distance Z is smaller by the bottom surface clearance C than Zm from the top surface of the cylinder, that is, the feed is carried out by a distance Z = Zm - C. However, when the machining electrode 10 is electrically discharge-machined from the top surface of the workpiece 12, Z force is applied. When it is fed in, the processing electrode 10
is consumed during machining, and if the length of the wear is ΔZ, then the tip of the machining electrode 10 is shallower than Zo by ΔZ at a depth 4=Z
It is located at the position of 0-ΔZ, and the depth of the machined hole 14 is also Zm and Δ
Only Z becomes shallower. Therefore, in order to process the workpiece 12 to a desired depth Zm, it is necessary to further process the workpiece 12 by a depth ΔZ.

However, the above bottom clearance c + it extreme wear length Δ
Since Z varies depending on the shape of the workpiece 12, electrical conditions, method of applying machining fluid, etc., it cannot be determined accurately. Therefore, Z of the machining electrode 10 is determined in advance by considering the electrode wear length ΔZ. It takes a lot of skill to send in only +ΔZ.

For this reason, conventionally, after processing to the state shown in FIG.
, and the corrected feed length Δ'Zi-Zo-Z.

was calculated, and the processing electrode 10 was further fed by ΔZ. In recent years, the automation of electrical discharge machining equipment has progressed through the use of numerical control devices, and the above-mentioned feeding of the machining electrode 10 has been automatically performed to improve work efficiency.

However, as mentioned above, in the conventional device, automatic operation is temporarily interrupted when correcting the feeding of the processing electrode 12.
The disadvantage is that the operator has to measure the depth 4 of the machined hole 14 during processing, and it is not possible to perform full automatic operation from the start of processing to the end of processing, which requires time and effort for processing work. There was.

Further, since the depth ZI of the machined hole 14 during the process was measured by an operator, measurement errors were likely to occur, and there was a drawback that accurate processing could not be performed.

For this reason, conventional attempts have been made to use the machining electrode 10 as it is as a contact probe and to sense the contact of the machining electrode 10 with the workpiece 12 to measure the depth zl of the machining hole 14. , in this method, the processed electrode 10 is
The machining electrode 10 senses contact with machining powder adhering to the circumference of the bottom surface of the machining hole 14, and since the clearance C is usually extremely narrow, the machining electrode 10 senses contact with the inner surface of the machining hole 14, resulting in a measurement error. there were.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to perform high-precision machining and improve work efficiency by automatically performing machining operations all at once. The purpose of the present invention is to provide an electric discharge machining device that can perform the following steps.

In order to achieve the above object, the present invention provides an electric discharge machining apparatus that is equipped with an electrode feeding device that feeds a machining electrode toward a workpiece and forms a machining hole of a desired depth in a workpiece. and a measuring glove for measuring the depth of a hole being machined, a contact sensing device for sensing contact between the measuring probe and the workpiece, and a contact sensing signal from the contact sensing device. A storage device that stores the depth of the hole to be machined during machining, and a feed reduction command device that issues a feed command to the electrode feed device based on the depth of the hole to be machined that is in the middle of machining, which is stored in the storage device. Before the machining hole of the workpiece reaches the desired depth, replace the machining electrode with a measuring probe to measure the depth of the machining hole during machining, and replace the measuring glove with the machining electrode again. The present invention is characterized in that the feeding of the machining electrode is corrected by a depth corresponding to the difference between the desired depth of the machining hole and the depth of the machining hole during machining, and machining operations are automatically performed all at once.

Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows a preferred embodiment of the electrical discharge machining apparatus according to the present invention, in which the machining electrode 10a is connected to the surface plate 16.
An electrode feeding device 18 is provided to feed the electrode toward the workpiece 12 placed above.

The electrode feeding device [1B] has a pulse motor 22 supported by a head 20, and a main shaft 26 is engaged with a pole screw 24 fixed to the rotating shaft of the pulse motor 22. Further, an automatic clamp device 28 is provided at the lower end of the main shaft 26, and the shank 30a of the processing electrode 10 is removably clamped by this automatic clamp device 28. Due to the movement, the main shaft 26 moves up and down via the ball screw 24, and as a result, the processing electrode 10 moves up and down.

Further, the apparatus of this embodiment is provided with an exchange device 34 for mutually exchanging the machining electrode 10 and the measuring glove 32 used for measuring the depth of the machining hole 14 during machining.

The exchange device 34 has a magazine 38 rotatably provided in a magazine box 36, and a plurality of storage holes 38a provided in the magazine 38 have processing electrodes 10b1 and measurement probes attached to the shanks 30b and 30c, respectively. 3
2 is stored therein, and by rotating the magazine 38, a desired processing electrode 10b or measurement probe 32 is selected. The exchange device 34 also has a swing arm 40 that is rotatably provided at the lower end of the magazine box 36 and is movable forward and backward, and up and down. between the processing electrodes 10a, 10b and the measurement probe 3.
2 transportation is carried out.

Furthermore, the apparatus of this embodiment has a contact sensing device 42 for measuring the depth of the hole 14 during processing.
consists of a switch 44, a resistor 46, and a battery 48 connected in series between the measurement probe 32 and the workpiece 12, and a contact sensor 50 connected in parallel with the resistor 46. The switch 44 is provided to prevent the contact sensor 50 from malfunctioning due to machining current flowing through the resistor 46 during electrical discharge machining. Then, with the measurement probe 32 attached to the automatic clamping device 28, the switch 44 is
When the measurement probe 32 is brought into contact with the top surface of the workpiece 12 and the bottom surface of the processing hole 14, a voltage is generated across the resistor 46 at the same time as the contact is made. This voltage is sensed by the contact sensor 50, and the point of contact of the measurement probe 32 is detected.

A numerical control device 52 is provided to drive and control the electrode feeding device 18 described above, and the numerical control device 52 is configured as follows.

In other words, a control program is input into the paper tape 54 in advance, and when an automatic positioning command is output to the processing device 56, the processing device 56Iri decodes the control program, and the computing unit 58 reads the decoded control program. The feed amount of the processing electrode 10a is calculated based on the program. Then, a feed command signal 100 is output to the pulse motor 22 based on the feed amount of the processing electrode 10a calculated by the feed command circuit 60.
The one-pulse motor 22 feeds the machining electrode 10a based on the feed command signal 100 until the machining hole 14 of the workpiece 12 reaches a predetermined depth during machining. At the same time, the feed command signal 100 is output to the output integration circuit 62, and its contents indicate the current value coordinates of the processing electrode 1Oa (measuring probe 32).

The numerical control device 52 also has a storage device 64 that stores the depth of the hole 14 that is being processed based on the contact sensing signal 102 output from the contact sensing device 42. The storage device 64 has a coordinate reading circuit 66 that reads the coordinate values of the measurement probe 32 based on the contact sensing signal 102 output from the contact sensing device 42, and the coordinates read by the coordinate reading circuit 66 are stored in the memory 68. coordinate value storage unit 68a,
68b. That is, at the same time that the contact sensor 50 senses the voltage generated across the resistor 46 and outputs the contact detection signal 102, the output integration circuit 62 outputs the read command signal 104 to the coordinate value reading circuit 66, and the coordinate value reading circuit 66 outputs the read command signal 104. The coordinates read in 66 are stored in the coordinate value storage section 68a in the memory 68 for each contact position of the measurement probe 32 (in this embodiment, the top surface of the workpiece 12 and the bottom surface of the processing hole 14).
, 68b. Note that when the contact sensing signal 102 is outputted from the contact sensing device 42 to the coordinate value reading circuit 66, at the same time, the feeding stop signal 106 is outputted from the contact sensing device 42 to the feeding command circuit 60, and the measuring glove 3
2 is stopped.

Furthermore, the numerical control device 52 has a feed command device that issues a feed command to the electrode feed device 18 based on the depth of the hole 14 that is being machined, which is stored in the storage device 64. The command device is also used as the feed command circuit 60. Based on the coordinates of the measuring glove 32 stored in the memory 68, the desired depth ZII of the machined hole 14 with the calculator 70 is determined.
Difference ΔZ between I and the depth Zm−ΔZt of the machined hole 14 during processing
The feeding amount of the machining electrode 10a corresponding to is calculated, and the feed command circuit 60t'i calculates the feeding amount and sends the υ correction signal 110 to the pulse motor 22 using the calculation signal 108 output from the t'i calculator 70.
is output, and the feeding correction of the processing electrode 10a is performed.

The embodiment of the present invention consists of the above configuration, and its operation will be explained below.

First, as shown in FIG. 1, the machining electrode 10a is moved from the top surface of the workpiece 12 to a depth Z corresponding to the desired depth Zm of the machining hole 14. We will explain the case where the data is sent up to the maximum.

As shown in FIG. 2, the processing electrode 10a is attached to the automatic clamping device 28, and when an automatic positioning command is output to the processing device 56, the processing device 56 clamps the paper tape 54.
The control program input to the computer is decoded. Based on the decoded control program, the processing unit 58
The feed amount of the pole 10a is calculated and the calculation result is sent to the feed command circuit 6.
When the transmission command signal 100 is output to the pulse motor 22, the transmission command signal 100 is output from the transmission command circuit 6o to the pulse motor 22. Accordingly, the pulse motor 22 rotates at a predetermined speed based on the feed command signal 100, and the discharge machining hole 14 is formed between the machining electrode 10a and the workpiece 12. Due to the consumption of the machining electrode] Oa during machining, the desired depth Zm of the machining holes 14 becomes shallower by ΔZ as shown in FIG. ing.

A characteristic feature of the present invention is that the depth Zm -Zo of the machined hole 14 is automatically measured during the process described above, and the depth Zm - Zo of the machined hole 14 is automatically measured.
4 desired depth Zm and the depth of the processed hole 14 during processing Zm-
The purpose of this is to correct the feeding of the processing electrode 10a by a depth zo corresponding to the difference between the depths z and z.

That is, during the above-described processing, the processing electrode 10a is raised as shown in FIG. 3(5), and the swing arm 40
When the electrode rotates and moves forward and grabs the shank 30a of the processing electrode 10a clamped by the automatic clamping device 28, the automatic clamping device 28 becomes unclamped. Then, the swing arm 40 descends, retreats, rotates, and advances to transport the processing electrode 10a directly below the magazine 38, rises, stores it in the storage hole 38a of the magazine 38, and then retreats.

Magazine 38 is then rotated to select measurement probe 32. Then, the swing arm moves forward 40 steps, picks up the shank 30c of the measuring probe 32, descends, retreats, rotates, and moves forward to carry the measuring probe 32 directly below the automatic clamping device 28, and then ascends, and the automatic clamping device 28 A shank of 30c is clamped. Thereafter, the swing arm 40 retreats and pivots back to its original position.

In this way, the measuring glove 32 is attached to the automatic clamping device 2.
8, the switch 44 is closed to prepare for measurement. Then, as shown in FIG. 3 (13), the measuring probe 32 first moves horizontally to the upper surface of the workpiece 12 by a specified distance as shown by the arrow, and then descends to the workpiece 12. When it comes into contact with the resistor 46, a voltage is generated across the resistor 46 depending on the contact position, and this voltage is applied to the contact sensor 5.
When detected at 0, a read command signal 104 is simultaneously output from the output integration circuit 62 to the coordinate value reading circuit 66. The coordinates Za of the upper surface of the workpiece 12 read by the coordinate value reading circuit 66 are stored in the coordinate value storage section 68Ji within the memory 68. Next, the measuring probe 32 is returned to the measurement starting point, descends down the machined hole 14 as shown by arrow E, and comes into contact with the bottom of the machined hole 14, and the coordinate Zb of the bottom of the machined hole 14 is stored in the memory 68 in the same manner as described above. Coordinate value storage section 6 within
8b. When this operation is completed, the measurement probe 32 rises and is replaced with the original machining electrode 10a by the above-mentioned replacing operation of the swing arm 40 and magazine 38, and the machining electrode 10a#'i is shown in FIG. Move to mid-processing position z1. The switch 44 shown in FIG. 2 is also opened to cut off the operation of the touch sensing device 42.

Next, the arithmetic unit 70 uses the coordinate value storage section 68a in the memory 68.
, 68b are read out, the raw distance ΔZ = Zm - (Z - - Zb) is calculated, and the calculation signal 108 is output to the feed command circuit 60. As a result, the feed command circuit 60 outputs a feed correction signal 110 to the pulse motor 22. Therefore, the processing electrode 10a is the third
Figure (As shown by Q, the rotation of the pulse motor 22 lowers the machining distance ΔZ, and the machining hole 14 has a desired depth Zm.
can be formed.

Similarly, in the above-described embodiment, automatic correction of the depth of the machining hole 14 of the workpiece 12 was described, but correction of the amount of oscillation due to consumption of the machining electrode 10a during oscillation machining, etc. It can be applied to repeated electrical discharge machining, such as correction of machining amount.

In addition, in the above-mentioned embodiment, the depth of the machined hole 14 during processing is measured from the voltage change caused by the contact between the measurement probe 32 and the workpiece 12, but a measurement method using a micro switch or the like may also be used. It has a similar effect.

As explained above, according to the present invention, the machining electrode is replaced with a measuring probe before the machining hole of the workpiece reaches a desired depth, the depth of the machining hole during machining is measured, and the measuring probe is replaced with the measuring probe. To automatically perform machining operations all at once by replacing the machining electrode again and correcting the feed of the machining electrode by a depth corresponding to the difference between the desired depth of the machining hole and the depth of the machining hole in the middle of machining. As a result, highly accurate machining can be performed and work efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the state of the machining electrode and the workpiece during machining, FIG. 2 is an explanatory diagram showing a preferred embodiment of the electric discharge machining apparatus according to the present invention, and FIG. FIG. 3 is an explanatory diagram of the operation of the shown device. Identical members in each figure are denoted by the same reference numerals 10a, lQb.
12 is a processing electrode, 12 is a workpiece, 14 is a processing hole, 18 is an electrode feeding device, 28 is an automatic clamp device, 32 is a measurement probe, 34 is an exchange device, 38 is a magazine, 40 swing arms, 42 is A touch sensing device, 52 a numerical control device, 6o a feed command device, 64 a storage device, 102 a touch sensing signal, and 11° a feed correction signal. Agent Patent attorney Shin Kuzuno - (1 others) Figure 1 Procedural amendment (voluntary) ■, Indication of case Patent application No. 57-043934 2
, Title of the invention: Electrical discharge machining apparatus 3, Person making the amendment 5, Detailed explanation column of the invention in the specification to be amended, Drawings. that's all

Claims (1)

[Claims] (1) In an electric discharge machining device that is equipped with an electrode feeding device that feeds a machining electrode toward a workpiece and forms a machining hole of a desired depth in the workpiece, the machining electrode and the machining hole that is being machined are a replacement device for exchanging a measuring probe for measuring the depth of a workpiece; a contact sensing device for sensing contact between the measuring probe and a workpiece; It includes a storage device that stores the depth of the hole to be machined, and a feed command device that issues a feed command to the electrode feed device based on the depth of the hole to be processed that is being processed while being stored in the storage device. Before the machining hole reaches the desired depth, replace the machining electrode with a measuring probe to measure the depth of the machining hole during machining, and replace the measuring probe with the machining electrode again to measure the desired depth of the machining hole. An electric discharge machining device characterized in that the feed of the machining electrode is corrected by a depth corresponding to the difference between the depth of the machining hole and the depth of the hole being machined, and machining operations are automatically performed all at once.