JPH0521690B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for setting machining conditions in electric discharge machining, and more specifically, the present invention relates to a method for setting machining conditions in electric discharge machining, and more specifically, the present invention relates to a method for setting machining conditions in electrical discharge machining. , relates to a method of setting machining conditions for creating a machining program for the series of machining steps of electric discharge machining when machining is performed using a plurality of machining processes of about 3 to 5 processes such as semi-machining, semi-finishing machining, and finishing machining. [Prior Art] Conventionally, electric discharge machining methods have been known in which a workpiece is sequentially machined in a plurality of machining steps with different electrical machining conditions using one electrode. In such a processing method, for example, first rough machining is performed, then semi-machining and semi-finishing machining are performed, and finishing machining is performed as the final step to obtain a processed product with desired dimensions and accuracy. This is generally widely practiced, and the accuracy and other finishing qualities of the processed product are influenced by various electrical processing conditions in each of these processing steps. Therefore, it is necessary to appropriately determine the machining conditions under which electrical discharge machining should be performed at each stage of these series of machining processes and create a machining program for each machining process. However, this decision required considerable experience and was so difficult that even experts were prone to making mistakes. The various electrical machining conditions mentioned here include the peak value (Ip) of the current waveform of the discharge current flowing during electrical discharge machining, the pulse width (τon) that is the duration of this current waveform, and the pulse width (τon) that is the duration of this current waveform. It is the pause width (τoff) of the voltage applied in a pulsed manner to By referring to various machining condition data provided by the manufacturer and own machining data, etc., and configuring the electrical parameters separately, the person can set electrical parameters that meet the required conditions such as the surface roughness of the workpiece. Electrical discharge machining was performed according to a machining program created by selecting and setting machining conditions for each machining process. In this way, an apparatus in which a machining operator sets machining conditions in advance for each series of machining steps and creates a machining program is disclosed, for example, in Japanese Patent Publication No. 47-4719. There is. [Problems to be Solved by the Invention] However, in the conventional electric machining device as disclosed in Japanese Patent Publication No. 47-4719, when creating a machining program by setting machining conditions, it is necessary to Setting of various electrical processing conditions in
The operator must individually set the settings on the boat based on the machining condition data table provided by the manufacturer or his own experience. Therefore, as mentioned above, various machining conditions for machining are This often results in inappropriate processing, resulting in economic and time losses. In addition, if an inexperienced worker can perform temporary machining, it may take a long time, or the machining electrode may be consumed more than necessary, or the roughness of the machined surface may be rougher than desired. This tends to cause some kind of inconvenience, and it has been difficult to achieve satisfactory processing. Therefore, an object of the present invention is to eliminate the need for an operator to create a machining program by setting individual machining conditions, when a workpiece is machined in multiple machining steps using one electrode. , some machining condition data such as the type of machining, electrode, material of the workpiece, and final machining targets such as final finished surface roughness, as well as machining data such as the amount of electrode reduction, and the dimensions and shape of the machined hole. To provide a method for setting machining conditions in electric discharge machining, which allows the creation of an appropriate machining program for a series of machining processes by inputting specifications, and enables the desired machining to be performed extremely efficiently. be. [Means for Solving the Problems] The method for setting machining conditions for electrical discharge machining according to the present invention to achieve the above object is characterized by:
a numerical control unit that controls relative machining feed between the electrode and the workpiece and movement in a direction perpendicular to the feed direction in response to machining data for performing machining; Machining using an electric discharge machining apparatus, which is equipped with a servo control section for maintaining the state during machining in a state required for electric discharge machining, and further has a machining condition selection and setting section consisting of an input switch section, a storage device, and a control device. In the condition setting method, the numerical data of the predetermined electrical machining conditions, the desired electrode, the material of the workpiece, and the overcut amount and machined surface roughness when machining under the electrical machining conditions are included. The plurality of sets of machining conditions are set by the control device based on the required number of sets of machining condition data including numerical data of various machining performances, and the designation and input from the input switch section when setting the electrical discharge machining conditions. storing program data in advance in the storage device to create a machining program for a series of machining steps from the data; and inputting the input when creating the machining program for setting machining conditions for a required workpiece A first step in which the type of machining is input by specifying whether electrode non-consumable machining is to be performed and the material of the electrode and workpiece, and a second step in which the desired final surface roughness of the workpiece is specified and input. a third step for specifying and inputting machining data regarding the amount of reduction in the electrode and the shape and depth of the machined hole; Select and read the machining condition data, and select one set of machining condition data that matches the final surface roughness data of the machining performance specified and input in the second step from among the many sets of machining condition data read out. Then, with the selection of the one set of machining condition data, one electrode is used to process the workpiece in multiple machining processes such as rough machining, semi-machining, and finishing machining with different electrical machining conditions. A set of machining condition data corresponding to each series of machining steps for machining is selected from the set of machining condition data read out using at least one data in the one set of machining condition data as an index, a step of creating a machining program for the series of machining steps by selecting and combining them based on the program data; and setting various electrical machining conditions in the power supply unit for each machining step of the machining program according to the data of the created machining program. At the same time, the relative machining feed amount between the electrode and the workpiece in each machining process of the machining program is controlled by the numerical control unit based on the created machining program and the designated input of the third step. The processing is performed by setting data regarding translational motion in a direction perpendicular to the feeding direction. Note that the electrode reduction amount here means 1/2 of the difference between the outer diameter dimension of the electrode used and the final machining target dimension, but the term electrode reduction amount is based on electrical discharge machining technology. Since this terminology is unique to this field, I will explain it briefly here. That is, in electric discharge machining, unlike in the case of other machine tools for cutting or grinding, a gap exists between the tool electrode and the machined hole of the workpiece at the end of machining. This interval is called a discharge interval or overcut, and generally, when the discharge energy per unit discharge is large, the machined surface roughness of the workpiece increases, and the above interval also becomes large. Therefore, in addition to the discharge gap or the machining gap between the electrode and the workpiece in the opposing feeding direction, there is also a gap between the electrode and the workpiece due to machining debris flowing along with the machining fluid. There is an overcut, that is, a gap between the opposing sides of the electrode and the workpiece in a direction perpendicular to the feeding direction, which is enlarged by the subsequent discharge. Therefore, in electric discharge machining, it is necessary to make the electrode smaller in advance in consideration of the overcut, according to the set electric discharge machining conditions, with respect to the final finished size. This reduction is called the reduction amount and is expressed on one side (radial dimension). According to the above, for example, the cross section has a predetermined size.
With a shaped electrode, the specified (feed) to the workpiece
When attempting to machine a deep hole with a certain set machining condition, the amount of electrode reduction is determined by the material of the electrode/workpiece and the amount of overcut that occurs when machining with the set machining conditions. However, depending on the machining conditions, electric discharge machining can include non-consumable electrode machining (bottom hole machining), low consumable machining, and consumable machining (through-hole machining), depending on the machining conditions. processing)
However, in order to simplify the explanation, we will discuss the case of machining in which the electrode is almost non-consumable. However, even if the type of machining is specified in this way, the present invention applies to rough machining, semi-machining, finishing machining, etc. using one electrode to process a workpiece under different electrical machining conditions. This is related to the method of creating and setting a machining program when machining is performed in multiple machining steps, and furthermore, in the first rough machining of the multiple machining steps, the relative direction of the opposing direction between the electrode and the workpiece is Even if machining is performed using the so-called Z-axis feed, in which almost no feed or movement is performed other than the machining feed, the machining conditions after the second machining step, such as semi-machining, are sequentially changed so that the energy per unit discharge is small. Since this is a process in which the machined surface roughness is reduced and the overcut is also reduced, in the process after the second process, even if the electrode is not consumed, at least from the relationship of the size of the overcut, it is perpendicular to the process feeding direction. It is necessary to perform processing while applying relative translational movement in the direction between the electrode and the workpiece. However, machining by applying translational motion in a direction perpendicular to the feeding direction is a compensation for the benefit of being able to perform machining in multiple steps without replacing the electrode, and it is stable due to machining while appropriately discharging machining waste. This is indispensable for performing highly efficient machining. As described above, when a workpiece is processed in multiple processing steps with different electrical processing conditions using one electrode of the present invention, the amount of electrode reduction is It is clear that it needs to be greater than the total amount of cuts, and if the amount of reduction is too large, the number of machining steps will increase, and the machining conditions for the first rough machining will become rougher, resulting in a shorter machining time. Although they tend to be shorter, it is difficult to achieve machining accuracy, so they should be avoided.
Conversely, if the amount of reduction is too small, the number of machining steps will be reduced, and the machining conditions for the initial rough machining will be closer to the final finishing machining conditions, and although the machining accuracy will be high, the time required for machining will be below the normal value. This should also be avoided as it will take 10 times as long. [Operation] According to the method for setting machining conditions in the electric discharge machining apparatus of the present invention, the input switch section of the machining condition selection setting section selects the electrode to be used, the material of the workpiece, and whether the electrode is consumable or not. When the type of machining, the final surface roughness as the final machining target to be applied to the workpiece, machining data regarding the shape and depth of the machined hole, and the amount of electrode reduction are specified and input, the control device of the setting section selects and reads out a set of machining condition data of the same type that corresponds to the type of machining specified and input from among the many sets of machining condition data stored in the storage device of the setting unit, and reads out the machining condition data of this read set. From among the data, select one set of machining condition data having machining performance (surface roughness data) that matches the specified input final surface roughness data, and further select at least one of the machining condition data of this one set of machining condition data. Using data such as surface roughness as an index, select a set of machining condition data corresponding to each series of machining processes such as rough machining, semi-machining, and finishing machining from among the many sets of machining condition data read out above. In combination, a machining program for the series of machining steps is created, and electrical machining conditions in the power supply section are automatically and sequentially set for each machining step using the data of this created machining program. Data regarding the relative machining feed amount between the electrode and the workpiece in each machining process of the program and the translational movement in the direction perpendicular to the feed direction are automatically generated using the data of this machining program and the input machining data from the switch section. By setting this in the numerical control unit, electrical discharge machining of a series of machining steps will be started.
Creation of a machining program for an optimal series of machining steps commensurate with the amount of reduction in electrode size and execution of the machining process do not depend on the operator's detailed setting work or experience, allowing the desired machining to be performed efficiently and without errors. be able to do it. [Example] Hereinafter, a method for setting electrical discharge machining conditions according to the present invention will be explained in detail with reference to an illustrated example. In FIG. 1, 1 is an electric discharge machining section, and 16 is a machining condition selection and setting section, in which a machining program for a series of machining steps is created by the machining condition setting method of the present invention, and the created machining process is performed. The electric discharge machining section 1 executes a series of targeted machining steps based on machining conditions set by a program. The electrical discharge machining section 1 places the set workpiece 2 on a predetermined plane (X-axis and Y-axis plane).
A machining table 3 supported by a frame (not shown) so as to be movable within the machining table 3, and a machining electrode 4 disposed facing the workpiece 2 set on the machining table 3 in the Z-axis direction. We are prepared. The processing electrode 4 can be raised or lowered in a direction perpendicular to the predetermined plane (Z-axis direction) by an electrode feeder 6 including a pulse motor 5, and the electrode feeder 6 is controlled by a servo control circuit. 7, the drive is controlled so as to maintain the distance between the workpiece 2 and the machining electrode 4 during electrical discharge machining at a predetermined length. On the other hand, the processing table 3 can be moved in two axial directions orthogonal to each other within the predetermined plane by two drive pulse motors 8 and 9.
9 is controlled by a numerical control device (NC device) 10, and can move the processing table 3 so as to draw a desired trajectory within a predetermined plane. An electric discharge machining power supply circuit 11 is connected between the workpiece 2 and the machining electrode 4. This circuit 11
These are a DC power supply 12, a switching transistor 13 for applying the voltage of the DC power supply as a predetermined voltage pulse to the discharge machining interval, and a resistance switching device for setting the value Ip of the discharge current flowing between the discharge machining interval. 14 are connected in series as shown, and a pulse signal _S1 from a pulse generator 15 is input to the base of the transistor 13 as a gate pulse. The pulse generator 15 can arbitrarily select and set the frequency f, on time τon, off time τoff, etc. of the pulse signal _S1 , which is its output signal, using the control signal _S2 from the setting section 16. It is becoming. Similarly, the resistance switch 14 can be switched to a desired resistance value by the control signal _S3 from the setting section 16, so that the discharge current amplitude Ip can be set to a desired value. Therefore, this electrical discharge machining power supply _circuit 11 _sets various electrical machining conditions Ip, τon,
τoff can be set to a desired value. The electric discharge machining section 1 further receives information from the machining condition selection and setting section 16, which includes an input switch section 17, a storage device 18, and a control device 19, as well as the type of machining (electrode consumable machining or electrode non-consumable machining) and the electrode 4. and each material of the workpiece 2, the value of the final finished surface roughness of the workpiece 2 as the final machining target, data regarding the shape and depth of the machined hole, and the processing used for the dimensions of the machined hole. By simply inputting the value of the electrode reduction amount, the workpiece can be machined through multiple programmed machining processes (rough machining, semi-machining, semi-machining) by the electrical discharge machining section 1 configured as described above. Finishing processing, finishing processing) are performed under appropriate electrical processing conditions, and the entire processing process is carried out using a single electrode to bring the workpiece to the desired dimensions.
The machining condition selection and setting unit 16 receives settings of machining conditions that enable machining into a shape and various controls during machining. The machining condition selection setting section 16 selects the type of machining described above, the material of the electrode and workpiece, the final finished surface roughness,
An input switch section 17 for specifying and inputting the dimensions, shape, and electrode reduction amount of the machined hole, or the shape and dimensions of the translational movement, and numerical data of certain selected electrical machining conditions, which will be described in detail later. and numerical data of various machining performance when machining with various electrodes, workpiece materials, and combinations under the machining conditions, and a specified input from the input switch section 17. A storage device 18 in which program data for creating a large number of machining programs related to a series of machining steps to be created using this set of machining condition data is stored in advance, and the data from the input switch section 17. By inputting a designation such as, the same type of machining condition data is read from among the many sets of machining condition data stored in the storage device 18, and a machining program consisting of an appropriate combination of a plurality of machining steps is created using the program data. A control device 1 such as a microcomputer is used to control the electric discharge machining section so that a predetermined machining can be performed according to the created machining program.
It has 9. Among the many sets of machining condition data stored in advance in the storage device 18, there are prepared many types of machining condition data that suit various machining requirements as follows. As is well-known, in electric discharge machining, there are various factors such as whether or not the machined hole bottoms out, that is, the type of machining, whether or not the machining is done without consumable electrodes, the materials of the electrode and workpiece used, and their combinations. Even if the electrical machining conditions are the same, the machining performance values as a result of the machining will vary greatly depending on these conditions, as shown in Figure 2. The machining condition data, which is a set of numerical data of electrical machining conditions and numerical data of machining performance when machining under the machining conditions, is divided into six groups, in the case shown in the figure, groups 1 to 3. ing.
Once the material of the electrode and the material of the workpiece are determined in this way, the machining performance in electrical discharge machining is determined by various electrical machining conditions, that is, machining speed [g/min], surface roughness [μRmax], The consumption ratio of the electrode [%] and the overcut amount [mm], which indicates the flow rate of the gap created between the machining electrode and the side wall of the machined hole of the workpiece after electrical discharge machining, are almost unique. It will be determined as follows. Tables 1 to 5 are numerical tables that combine numerical data of electrical machining conditions and machining performance when a certain machining is performed, showing the relationship between these, i.e., Tables 1 to 5 show examples of sets of machining condition data. Shown below. Therefore, Table 1 of Tables 1 to 5 corresponds to the machining condition data of the group shown in Figure 2 above, and the type of machining is bottoming machining, that is, machining with no electrode consumption. When the electrode material is copper and the workpiece material is steel, the machining condition data of the set that combines the electrical machining conditions and numerical data of machining performance is from finishing machining to semi-finishing, semi-machining...rough machining. Up to 7 types or 7 stages have been shown, and the processing condition data for these sets is not shown as the processing condition data for the other sets of Tables 2 to 5 or these tables. The machining condition data is stored in advance in the storage device 18 of the machining condition selection and setting section 16 along with each set of machining condition data corresponding to each group from the group shown in FIG.

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〔Effect of the invention〕

According to the method for selecting and setting machining conditions in electric discharge machining of the present invention, as described above, the machining target value, the material of the workpiece and the electrode, the type of machining, etc., which are not related to the operator's skill level, etc. By just providing this data, the optimum machining conditions required for each stage of the series of machining processes in electrical discharge machining are automatically selected, and a machining program for the series of machining processes is created. If so, the data of the machining program created as a result of the modification will be used to set the conditions for each part of the equipment for electrical discharge machining.
It is possible to easily set machining conditions for machining using an electrical discharge machining device without requiring any skill, and this has an excellent effect that anyone can efficiently perform highly accurate electrical discharge machining.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an electric discharge machining apparatus for carrying out the method of the present invention, FIG. 2 is a flowchart for explaining the machining program selection operation in the apparatus of FIG. 1, and FIG. The figure is an explanatory diagram for explaining how to determine the feed amount for each process in a series of machining processes, and Figure 4 is an explanatory diagram for explaining how to determine the amplitude increment of translational movement for each process. be. DESCRIPTION OF SYMBOLS 1... Electric discharge machining section, 2... Workpiece, 3... Machining table, 4... Machining electrode, 5... Pulse motor, 6... Electrode feeding device, 7... Servo control circuit, 8, 9... Drive pulse motor, 10... Numerical control device, 11... Power supply circuit for processing, 12...
DC power supply, 13...Transistor, 14...Resistor switch, 15...Pulse generator, 16...Machining condition selection setting section, 17...Input switch section, 18
... Storage device, 19 ... Control device, S ₁ ... Pulse signal, S ₂ ... Control signal, S ₃ ... Control signal, S ₄ ...
Control signal, S ₅ ... Electrode feed amount signal, S ₆ ... Control signal.

Claims (1)

[Scope of Claims] 1 (A) A power supply unit that can switch and set various electrical machining conditions in electric discharge machining, and a power source unit that can switch and set various electrical machining conditions in electric discharge machining, and a numerical control unit that controls machining infeed and movement in a direction perpendicular to the infeed direction, and a servo control unit that maintains the machining state between the electrode and the workpiece in a state necessary for electric discharge machining. In a method for setting machining conditions for an electric discharge machining apparatus having a machining condition selection and setting section comprising an input switch section, a storage device, and a control device, the method further comprises: (B) numerical data of predetermined electrical machining conditions; A desired number of machining conditions, which are sets of overcut amount and numerical data of various machining performance, including machined surface roughness, when machining is performed under the specified electrical machining conditions under the specified electrode and material of the workpiece. data, and program data for creating a machining program for a series of machining steps from the plurality of sets of machining condition data by the control device based on designation and input from the input switch unit when setting electric discharge machining conditions. (C) When creating the machining program for setting machining conditions for a desired workpiece, the input switch section determines whether the type of machining is electrodeless machining or not; A first step of specifying and inputting the material of the electrode and workpiece; a second step of specifying and inputting the required final surface roughness of the workpiece; and a reduction amount of the electrode and the shape and depth of the machined hole. (D) selectively reading out the set of machining condition data of the same machining type from the storage device in accordance with the designation input in the first step; Select one set of machining condition data that matches the final surface roughness data of the machining performance specified and input in the second step from among the many sets of machining condition data; Depending on the selection of condition data, a series of machining steps for machining a workpiece using a single electrode through multiple machining steps such as rough machining, semi-machining, and finishing machining with different electrical machining conditions. The set of machining condition data corresponding to
At least one set of processing conditions in the data
(F) creating a machining program for the series of machining steps by selecting and combining the selected and read sets of machining condition data based on the program data; The electrical machining conditions are sequentially set in the power supply unit for each machining process of the machining program according to the data, and the numerical control unit The machining is performed by setting data regarding the relative machining feed amount between the electrode and the workpiece in each machining step of the machining program and the translational movement in a direction perpendicular to the feed direction. How to set machining conditions for electrical discharge machining equipment.