FR2530518A1 - ELECTRONIC DEVICE FOR ADJUSTING THE DEPTH OF MACHINING IN AN ELECTRO-EROSION MACHINING MACHINE - Google Patents

Abstract

THE INVENTION RELATES TO AN ELECTRONIC APPARATUS FOR ADJUSTING THE DEPTH OF ELECTRO-EROSION MACHINING. IT RELATES TO AN ELECTRO-EROSION MACHINING MACHINE INCLUDING AN APPARATUS 12 FOR ADJUSTING THE DEPTH OF THE SHAPED HOLES. THIS APPLIANCE INCLUDES A CONTROL PANEL WHICH INCLUDES A DEVICE 38 INDICATING AN INITIAL DEPTH LIMIT, DEVICES 40, 42 INDICATING THE LENGTH OF ELEMENTARY MACHINING STEPS, A DEVICE 44 INDICATING THE NUMBER OF MACHINING STEPS AND DEVICES FOR DISPLAY 48, 50 SHOWING THE CURRENT VALUE OF THE PARAMETERS. A MICROPROCESSOR 28 INCORPORATED IN THE APPARATUS TRANSMITS DATA TO A MICROPROCESSOR 24 OF THE MAIN CONTROL OF THE ELECTRO-EROSION WORKING APPARATUS. APPLICATION TO THE EXECUTION OF VERY PRECISE HOLES IN PARTS BY ELECTRO-EROSION.

Description

The present invention generally relates to

  electro-erosion machining machines and more specifically the electronic control of

  the machining depth obtained in such a machine.

  EDM machines have been used satisfactorily for the machining of very precise holes in objects The advantages of such machining are well known and therefore not repeated It is sufficient to note that the Electro-erosion machining can give accurate results where other processes and devices are totally unable even to approach

  the characteristics given by the electro-machining

  erosion Despite the many advantages of EDM machining, there are particular products whose machined holes must be extremely accurate. An example of this is the machining of many blind holes in a part, the depths of the holes being Another example is the machining of several through holes, when it is important that all the electrodes pass through at the same time. Improvements in the adjustment equipment of EDM machines are presented by the control installation marked "CP-60" and carried out by the Applicant.

  is based on a microprocessor which allows an improvement

  This control is an important step towards the ultimate goal of producing a control

  maximum flexibility In such an order, the conditions

  machining operations or indicators of these

  real-time conditions, are controlled during progression, and the type of adjustment is adapted simultaneously

  controlled conditions or indicators corresponding to

  to ensure that the current machining operation is optimized

  For example, such a very flexible control can

  on the one hand to ensure faster machining when

  real swimming is easier than expected and can on the other hand reduce the machining speed when the actual operation

  machining is more difficult than originally planned -

  The invention constitutes an improvement of a

  control apparatus of an electromechanical machining

  erosion, allowing the realization of orders

  bring together such very flexible or adaptive controls.

  The invention more specifically relates to an electrical apparatus

  depth adjustment tronic which is used in conjunction with the main control of the EDM machine The depth control apparatus according to the invention acts on data

  selected from entry which are relative to the advance of elec-

  machining trodes and accordingly to the depth of the holes machined in the workpiece, and it cooperates with the command

  in such a way that the difficult problems

  hole machining ciles, for example previously indicated

  in the case of blind holes or the simultaneous crossing

  born from several holes, are solved Thus, the invention

  particularly suitable for improving

  properties of an electro-erosion machining

  that it precisely mills several blind holes at precisely determined depths, and when electrodes have to cross simultaneously

  machined through holes in a room The role es-

  of the electronic depth adjustment device

  The invention is therefore an accurate determination of the depth of the ends of the machining electrodes by

  The setting allows for the elimination of

  deterioration of the facing wall when machining in a cavity and removes

  In view of the electronic nature of the application

  such depth adjustment of the invention and the electronic nature of the main control, the answer

  the actual machining condition is practically instan-

  tane, so that the depth adjustment and the

  simultaneous are accurately realized.

  In summary, an advantageous embodiment of depth control apparatus has its own

  microprocessor that receives input data that can

  to be chosen and which come from switches

  input selectors mounted on a control panel.

  The microprocessor acts on the data transmitted by these switches and transmits output data which depends on the input data that has been selected and which is transmitted to the microprocessor of the control

  The electronic device for adjusting the pro-

  the founder therefore transmits information relating to the machining depths, and the main control acts

  on this information and rule the machining process.

  The data transmitted by the switches on the control panel has an initial depth limit,

  a first desired machining step, a second desired step of

  In addition, the control panel has a switch for

  to select a desired mode of operation of the

Adjustment depth.

  The microprocessor of the control unit

  depth is programmed by separate sets of instru-

  exploitation tructions and the particular game of

  in the course of execution is determined by the

  control panel mode selector switch In a first mode of operation, the microprocessor acts on the selected initial depth limit, the desired first machining step and the desired number

  of machining step, so that the microprocessor of the ap-

  Such a depth-of-adjustment system transmits to the main microprocessor control signals such as

  electrodes advance initially to the initial limit

  the desired depth, and then advance during a succession of machining steps, each machining step corresponding to the setting of the first desired machining step and the number of such machining steps being equal to the number of machining steps;

  chosen from no machining In the second mode of operation

  In addition, the microprocessor of the electronic depth control apparatus acts on the selected initial depth limit, the desired second machining step and the desired number of machining steps for transmission to the microprocessor. of the main control, signals such as this main control causes a simultaneous advance in unison of the electrodes to the desired initial depth limit, then a repeated advance during successive machining steps equal each to the second desired step machining that has been set, the number of steps being equal to the desired number of machining steps that

was chosen.

  A crossing detection device is

  also used for both modes of operation.

  In the first mode of operation, the device

  crossing detection system transmits a fault indication when a crossing is detected at a time

  before the end of the complete sequence of

  The first mode of operation is preferably used during the machining of blind holes. , and accordingly a fault signal is transmitted when a

or several holes went through.

  The detection of the bushing is used in the second embodiment for two functions. One of them is the detection of the desired bushing, indicating that all the machined holes have gone through at the same time and that the cycle is thus completed. In this regard, the feedthrough signal is used to stop the machining cycle in such a way that only one additional second desired machining step can be made after the machining step in which the feedthrough has been detected. -though the desired number of machining steps did not reach the number

  previously set on the control panel.

  The operator can then check the part to make sure that all the holes have been machined, although the actual number of machining steps is less than

  selected number set on the control panel

  conde function of the detection of the crossing, in

  the second mode of operation, relates to a

  In this respect, when the crossing is detected during the advance of the electrodes to the initial limit of the depth, a fault indication is transmitted. This indication is desirable because it is preferable that the crossing takes place during one of the second desired machining steps rather than during the initial advance of the electrodes to the initial depth limit Thus, it may be noted that the second mode of operation is chosen when the simultaneous traversal

is wanted in several holes.

  Another characteristic of the electrical apparatus

  Precision Depth Tuning Tread Features

  a new advance of the electrodes, on the electrical support

  trodes, at the end of the arrival of the electrodes to the desired initial depth limit, as well as a new advance at the end of each successive machining step This new advance of the electrodes is intended to maintain a predetermined relationship between the ends of all the electrodes One of the problems posed by the machining with several electrodes is the possibility of an irregular wear of the ends When several blind holes or through holes are machined by several electrodes placed on a common support, it is necessary that the ends electrodes have a predetermined relationship so that the desired relation between the depths of the blind holes in the first case and the simultaneous crossing of the holes opening in the second case is always

  As a result, the electronic device for

  depth setting according to the invention ensures a new advance of the electrodes or their training at the end of the initial advance to the desired initial depth limit and at the end of each machining step This new advance is obtained by placing implementation of totally conventional operations that are not described in detail The electrodes

  are preferably brought away from the room

  only at a location where the new real advance

is realized.

  Another advantage of the invention is that the

  such a depth control electronics is a

  seems that can be conveniently associated with

  to a conventional electro-machining machine.

  erosion In addition, it allows the adjustment of the depth to several machining stations by electro-erosion, although

  that the detailed description of an embodiment

  advantageous, given later in this

  simply circles the device's cooperation with a

  single erosion machining station.

  The electronic device for depth adjustment

  according to the invention has input devices which can

  to be chosen and which are mounted on a

  command, the latter being particularly convenient

  for the operator of the machine and allowing him to

  ci to quickly and accurately adjust the parameters

  The invention implements a fundamental adjustment

  mind corresponding to a piece, which is determined and

  set using the switches on the control panel.

  The operator can observe the progress of the machining and, in the event of a fault, he can, if necessary, modify the settings. When a machining cycle is finished, the operator can observe the workpiece and determine if a

  additional machining is necessary.

  In this case, the operator can conveniently and quickly

  to adjust the depth parameters in such a way

  that the work can be completed quickly and efficiently

  Therefore, in the case of variations such as size, hardness, etc. from one part to another, the invention is particularly suitable for the rapid processing of parts having such differences.

  the invention not only improves the precision and accuracy

  machining operations but still allows

  an increase in the number of pieces that can be processed.

  It is also desirable for the control panel to have a digital readout indicating the accumulated depth. The operator can ignore the position of the ends of the electrodes.

  at any time during machining operations.

  Other features and advantages of the

  come out better from the following description.

  made with reference to the accompanying drawings in which FIG. 1 is a block diagram of a

  electro-erosion machining machine comprising:

  such electronic depth control according to the in-

  Figure 2 is a flowchart illustrating

  a first mode of operation of the electronic apparatus

  depth adjustment device according to the invention; and Figure 3 is a flowchart illustrating

  another mode of operation of the electronic apparatus

  depth adjustment device according to the invention.

  FIG. 1 is a diagrammatic representation of an electro-erosion machining machine which carries the

  general reference 8 and which includes a main command

  10 with which the electronic device is associated

  12 depth adjustment according to the invention.

  The EDM machine 8 comprises a plurality of individual electrodes 14 mounted on a common carrier 16 A slave driving device 18 is associated with the carrier 16 and causes the advance

  and the decline of this support 16, and consequently of the elders

  trodes 14, relative to the part 20 to be machined by the device The support also includes a conventional mechanism for advancing the electrodes again

  carried by the support so that the ends of the electri-

  trodes keep a desired orientation.

  The apparatus further comprises a generator 22

  electro-erosion machining that is associated with electro-

  trodes 14 and to the piece 20 so that it transmits the machining current The control of the apparatus is provided by the control 10 which is an electronic assembly which comprises a microprocessor 24 as well as additional electronic circuits and components which are

  generally identified by the rectangle 26 and

  put the selection and reaction-parameters of usi-

  The main control is integrated with the driving device 18 and the generator 22 so that the support 16 is put into position by the driving device according to the signals coming from the

  electrodes 14 taking a corresponding position.

  As a result, the driving device is intended to advance the electrodes 14 towards the workpiece and to maintain them in the desired relative position with respect to the workpiece 20 with which they delimit a machining space. , while the generator 22 transmits a machining current in the air gaps or spaces formed between the individual electrodes 14 and the part, so that the operations

  desired machining of the part can be performed.

  The individual electrodes 14 provide in this way

  effective machining of several holes in a part 20.

  Each hole may have any section of desired shape that corresponds to the shape of the electrode that is machining the hole. The actual machining operations are performed in the vicinity of the tip of each electrode 14 relative to each other.

  the hole formed by it in the room and consequently

  when there is a gap or working gap between each electrode tip and the workpiece, a machining current - by electro discharge or electro-erosion circulating

so in this space or gap.

  The components marked with the general reference 26 determine the selected machining parameters ensuring

  the operation of the machine for machining

  erosion, such as forward and reverse speeds, machining current intensity, and other well-known parameters used in machining operations

  electro-erosion Most of the equipment

  The above described description, except for the electronic depth adjustment device 12, is part of a known set such as the set "CP-60" set to

point by the Applicant.

  The electronic device 12 for adjusting the depth

  deur according to the invention is associated during operation

  this apparatus already known and includes, as

  1, its own microprocessor 28 and a control panel 30 is generally intended to transmit to the microprocessor 28 input data that can be selected and which depends on the depth adjustment of the ends 14- electrode

  compared to the piece 20 In addition, an entry way-

  output 32 is associated with the microprocessor 28 and an output channel 34 is associated with the microprocessor 24 of the main control of the electro-erosion machining machine This last input channel 34 may be a part existing in the main control

  microprocessor or it may be a device

  then added The two entry ways-

  output 32, 34 are themselves associated with a circuit

  bidirectional interface placed between the two micro-

  processors 28 and 24 and intended for the transmission of

data signals.

  A position transducer 36 is also associated with the electronic device for depth adjustment. An advantageous embodiment of such a transducer

  36 is a linear variable differential transformer.

  This transducer is mounted between the part 20 and the support 16 so that the effective output inductance of the transducer is a function of the position of the support 16 and consequently the ends of the electrodes 14 with respect to the part 20, although the figure represents schematically the input of the transducer mounted between

  the piece 20 and the support 16, it should be noted that the trans-

  driver can be mounted on the table that carries the piece

  and associated with the training device at a location

  The main consideration, however, is to obtain with the aid of the transducer a precise measurement of the position of the ends of the electrodes with respect to the piece 20.

  output of the transducer reaches a microphone input

  processor 28, and a signal representative of the posi-

  the ends of the electrodes reach this microprocess-

  The following description shows in a way that

  more accurate how this position information is

used later.

  We now consider in more detail the

  order number 30 A number of devices

  input that can be selected is mounted on the panel.

  In the embodiment shown, these input devices are in the form of coded wheel switches which can each be selectively set to one of the decimal digits 0-9. Particular inputs for selection may optionally be used. An input data element which may be selected on the control panel and transmitted to the microprocessor 28 is the initial depth limit, as indicated by reference numeral 38. entry of this Initial Limit has four coded wheel switches

  having an increasing weight from left to right, for example.

  The input data that can be selected are de-

  terminated by setting the switches of the input device 38 and represent the initial advance of the

support 16 to the room.

  Another input device 40 corresponds to the mode 1 data and another input device

  42 corresponds to mode 2 data Each of these

  positive input 40, 42 has two switches indicative of

  viduals, one of them having a higher weight than the other Another input device 44 gives a number

  This input device has two

  44 a, 44 b, the switch 44 a being associated with the data of the mode 1 and the switch 44 b with the device 42 of the data input of the mode 2 In summary, when the device operates in mode 1, the electrodes,

  when they have advanced to the initial limit of

  deur set by the device 38, advance successively by machining step corresponding to the mode 1 data indicated by the switches 40, the number of machining steps being determined by the setting of the switch 44 a Correspondingly, when the operation of the mode 2 is chosen, the electrodes, when they have

  advanced to the initial depth limit, -provide succes-

  endlessly by machining step corresponding to the mode 2 data indicated by the switches 42, the number of steps being established by setting the switch 44 b In other words, the number of cycles corresponds to the number

no machining.

  It should also be noted that the settings of the

  44a, 44b determine which operating mode (s) are used Normally, one of the two switches is set to zero and the other to a non-zero number, equal to the desired number of steps machining, and in this case it is the particular switch 44a or 44b which has been set to a non-zero number which determines the next mode of operation. For example, when the switch 44a of the mode 1 is at zero and the switch 44b of the mode 2 to 5, the apparatus operates in mode 2 with five machining steps Similarly, when the switch 44b of the mode 2 is set to zero and the switch 44a of the mode 1 to five, the Depth Control Unit Operates in Mode 1 and Performs Five Machining Steps After Feeding

  at the initial depth limit.

  In addition, the control panel 30 includes control lamps 46a and 46b which selectively light up according to the particular mode or modes selected using switches 44a, 44b. Accordingly, when mode 1 is chosen, the lamp 46a lights up and, when

  mode 2 is chosen, the lamp 46 b lights up.

  A reading device 48 is also associated with the number of cycles and it comprises a device with a

  decimal digit which indicates the number of steps

  Actual swimming during operation A four digit reading device 50 is placed near the device 48 and displays the accumulated depth of the electrodes from the initial electrode advance point. Two additional indicator lamps 52 and 54 are mounted on the panel. The lamp 52 is a cycle indicator lamp that illuminates when the electronic depth control device operates in one of these two modes. The other lamp 54 is a fault indicator lamp which is controlled by certain conditions. operating modes as described in more detail in the remainder of this specification so that it gives an indication of defect. Thus, it may be noted that the panel 30 of

  command provides a convenient grouping for deter-

  the desired parameters for adjusting the depth of

  for the indication to the operators of the state of

  machining operations carried out with the aid of

Adjustment depth.

  A switch 56 is also associated with the panel

  command and it allows the selection of the units of

  on data input devices 38, 40 and 42.

  This is a coded wheel switch and it allows the selection of units in distance or time In the case of distance, the units can be following

  the metric system or the Anglo-Saxon system.

  The essential function of the electronic apparatus

  The depth adjustment system 12 is to subdivide an electro-erosion machining cycle into a number of sub-cycles allowing for further advance or re-training of the electrodes so that the depths and / or

  the holes are more precise and uniform.

  In some applications of the apparatus of

  depth adjustment, it is desirable that an indi-

  cation of the crossing is obtained This crossing

  appears when one or more of the 14 tips of electro-

  crosses the part being machined and form a hole that opens We now consider quickly

  how is such a crossing detected.

  An advantageous method of detecting

  paid is the control of the main machining speed through a workpiece and the control of the average speed during this machining The traverse can be determined as a percentage exceeding 100% of the average machining speed. of one or more ends of electrodes exists, the resistance

  in advance is reduced so that the electronic control

  It is important to note that the particular number chosen corresponds to a range of tolerances in the case of an increase in the speed of advance of the support and consequently of the electrodes. A suitable selection of the increase in percentage allows a determination of a crossing. and the actual number can therefore vary from one operation to another The calculation of the crossing can be done electronically on one or the other

microprocessors.

  FIG. 1 having been described, it is considered

  now other details of the operation of the appa-

  electronic control 12 depth adjustment and we get

  refers to this effect in Figure 2 This is an organization

  nigram of the logical operations implemented during the operation of the electronic control device

  depth in mode 1 It should be noted that the function

  In mode 1 is chosen for example when blind holes and non-through holes must be machined in the room.

  Before considering the detail of the function

  It is advisable to consider the procedure for placing a part, since it determines to a certain extent the setting of the input switches that can be selected.

  a suitable holding device or table in the

* Proper placement, where the electrodes can machine the desired holes When the workpiece is so adjusted, an approximate position of the final depth of the holes can be obtained One can also know the initial point occupied by the ends of the electrodes With these two information elements, the total distance ahead of the ends of the electrodes during the complete machining cycle,

  from the initial point to the end point of each hole, is

  It is also known where the ends of the electrodes begin to move relative to the surface of the workpiece in which the holes are to be machined, and it may or may not be the surface of the workpiece.

  the room itself As a result, the settings of the dis-

  Positive inputs can be performed with all this information, given the machining characteristics of the particular EDM machining machine used and the particular parts to be machined, although

  that the depth adjustment is accurate.

  During the machining operation, the ends of the electrodes may exhibit wear and this may be uneven from one electrode to another. For example, this phenomenon occurs when the surface of the workpiece is inclined with respect to the horizontal plane. and when

  the ends of the electrodes are placed in a horizontal plane

  In other words, in this case, some of the ends of the electrodes start machining the corresponding holes before other electrodes When an electrode has a large or irregular wear while the criteria relating to the depth or crossing simultaneous of a piece are very tight, a

  increased number of new advance cycles, with a

  penetration distance, that is to say for steps

  machining, and may be necessary for the elec-

  trodes keep the same length during the execution of the corresponding holes So, although we consider

  that a complete machining cycle involves an initial advance

  It should be noted that, in practice, several similar machining cycles may actually be necessary for the execution of the machining operations in the desired manner on a single machine.

given piece.

  When setting the data input devices, the initial depth limit is set to a desired value that is less than the total distance of travel from the starting point of the electrode tips to the final depth of the holes.

  main consideration for obtaining a profunda-

  The exact number of holes is the length of the machining step and the number of steps used. Consequently, the setting of the depth limit is normally calculated after

  the selection of the machining step and the number of such steps.

  However, this is not an imperative in all

cases.

  Accordingly, in view of the foregoing considerations, it is now considered in more detail

  FIG. 2 which is a flowchart representing the function

  This flowchart of FIG. 2 represents the logical sequence in which the microprocessor 28 is programmed. The detailed program can be formed according to the flowchart by a

  competent programmer who is familiar with standard

  microprocessor programming, so it is not necessary to incorporate details from an example

  In this paper, moreover, the invention

  in its general form is not limited by the.

  particular details of a program and so it should be noted

  that the invention may implement a program

  conch selected from a number.

  The initial conditions of adjustment of the

  are the setting of the ends of the electrodes in the initial or reference position The cycle begins

  as indicated by reference 60 and the first

  The operation performed after the beginning of the cycle is indicated by the reference 62. This operation comprises reading and memorizing the setting of the initial depth limit given by the switches 38 and reading and storing the data of the switches. with the reference 64

  includes the loading of the data corresponding to the

  Initial depth setting chosen in a register.

  The next operation 66 is the transmission, by the microprocessor, to the main control and through the input channels 32 and 34 of a signal which is processed by the main control so that the EDM machine is implemented and that the slave drive device 18 advances in an initial operation to the initial depth limit When the ends of the electrodes are in proximity so that a machining current can be driven, the holes are machined L machining can be done during the entire initial advance to the initial depth limit, for only part of that initial advance or it may not

  be performed during this initial advance.

  While the electrodes are advancing towards the initial set limit, the microprocessor 28 controls the advance of the electrodes. The operation is performed using the signal from the position transducer 36 and which is transformed into a position data signal that the microprocessor compares to the contents of the register

  which contains the initial depth limit data.

  This comparison operation is indicated by the reference

  68 and it is executed with a repeating frequency

  which is greater than the advance frequency of the electrodes so that the position of the electrodes is very frequently compared to the depth setting and no overshoot is possible. It should be noted that there is a feedback loop, in the operations of depth control, so that the actual depth

  is checked repeatedly.

  When the depth limit has been reached, the microprocessor 28 transmits to the microprocessor 24 a signal as indicated by the operation 70. This signal

  causes the electrode and electrodes support

  trodes themselves under the control of the device 18

  A new advance of the electrodes

  the support is also ensured during this time, this new advance of the electrodes avoids the defects

  of regularity in the machining operations, these

  faults due to irregular wear of the tips, so that the ends of the electrodes are maintained in

the relative positions desired.

  When the initial advance to the limit

  depth has been executed, the command pro

  voce additional sub-cycles corresponding to individual machining steps Before a machining step

  can begin, a determination must be made.

  It implements a comparison executed as indicated by the operation 72 which ensures the comparison of the number

  number of cycles to the number of cycles indicated by the

  At the beginning of the cycle, the actual number is

  to zero, so that the figure O is displayed by the

  during the initial advance to the initial depth limit Before the first machining step sub-cycle begins, the operation of comparing the actual number of cycles and the selected number of cycles

  given by the switch 44a is executed.

  If a equality is not detected, the number of cycles is increased by one unit as indicated in step 74. An update 76 of the initial depth limit data previously loaded in the register 'is then triggered. In other words, a value corresponding to the data of the machining step chosen in mode 1, given by the selector switches 40, is added to the contents of the register so that a limit given

  depth equal to the initial setting of

  foundry increased by a machining step is formed A

  general is transmitted to the microprocessor 24 and this latter trans-

  puts in turn a signal to the driving device 18 so that the ends of the electrodes have Vancent towards the

  piece so that the first machining step is executed.

  The machining operations continue, the depth being verified in the verification loop 68 This procedure (comprising the operations 68, 70, 72, 74,

  76) is repeated until operation 72 of comparison

  reason detects the equality between the actual number of cycles and the setting of the switch 44a When the equality is detected, a signal is transmitted, during the operation 78, and indicates that the total depth has been reached,

  this operation constitutes the end of the cycle (80) and

  in most cases that the work was carried out

  cut (operation 82) However, as indicated above, it is possible that one or more additional cycles

  (corresponding to the same or different settings

  fences) must be carried out according to the nature of the

  particular while the machining operations

  are executed, the device 50 for reading the pro-

  Cumulative Founder gives an indication of the position

  This indication is transmitted by the information of the transducer 36 of position so that, at any time, the position of the ends of the electrodes is displayed for the operator. In addition, during this time, the indicator light 46 a mode 1 is illuminated and, during the machining cycle, the lamp

52 is also enlightened.

  Since mode 1 operation is normal

  When a number of blind holes are machined simultaneously, no traversal is expected. The presence of a crossing therefore indicates a problem. The adjustment device ensures the illumination of the fault warning lamp. a crossing is detected at any time during the implementation of the machining operations while the operation

-in I mode is in progress.

  The foregoing description relates to the function

  of the depth control apparatus according to the invention during mode 1.

  2 is now considered with reference to FIG.

  Figure 3 shows the possible use of mode 1 and mode 2 operations at a time;

  however, it does not indicate the details of the

  In one mode, one of the rectangles represents this operation in mode 1 which has been described with reference

in Figure 2.

  Operation in mode 2 is analogous to

  in many respects to that of Mode 1 Mode 2 is used

  normally read for crossing through holes, accurately The starting point corresponds to the setting

  ends of the electrodes in the initial position, and.

  the cycle begins (100) The data relating to the initial depth limit of the selector switches 38 and the step indicated by the switches 42 are read and stored (102) by the microprocessor 28 The register

  is responsible for the data corresponding to this initial limit

  the microprocessor 28 transmits to the microprocessor 24, via the interface circuit, a signal which causes the spark erosion machining generator to be actuated and the electrodes to advance towards the piece under the action

  of the main order so that the operations

  (106) During this time, the profunda-

  Penetration depth (that is to say the advance of the ends of the electrodes) is controlled using the loop identified by the reference 108 This depth verification

  is similar to that of mode 1 operation; How-

  In addition, it includes an additional determination which is the determination of crossing detection.

(110).

  It is assumed that the crossing has not been detected, and the loop 108 has exactly the same course as

  the corresponding loop 68 of FIG.

  Just downstream of the loop 108, the operation

  112 determines whether Mode 1 has also been chosen.

  poses that the mode 1 operation was not chosen (usual case) and as soon as the depth limit has been reached, the selection of the operation in mode 2 is determined during the operation 114.

  the procedure corresponds to this case and the main order

  blade receives a suitable signal, the slave device

  causing a recoil (116) The determinations

  * tions are still executed almost instantaneously

  so that when the initial depth limit

  has been reached, it is not exceeded.

  are advancing again in relation to their support for this

  moment The initial advance of the electrodes is then ter-

  mined, and the machining cycle can then implement the sub-cycles during which the individual steps

machining are performed.

  For this purpose, the mode 2 data, indicated by the switches 42, are read and transformed into

  data which is added to the register containing the data

  depth limit during operation 118, so that the depth limit is updated and takes a new value that is equal to

  initial limit of increased depth of the

  born in mode 2 as shown on switches 42.

  After this update, the EDM machine is in operation and the driving device

  18 advance so that the machining operations are

  followed (120): The command then executes a verification routine 122 in which the depth is verified

  so that the fact that the limit handed over to

  has been reached or determined. It is an operation

  similar to subprogramme 108.

  The operation also includes a determination of the possible detection of the crossing (124)

  assumes that the crossing was not detected, and the,

  machining ration continues then until the

  depth update limit is reached when

  that this phenomenon exists, the electrodes recede and then advance again (126) and the fact that the number of cycles in mode 2 has been executed is determined (128) If this is not the case, the number of cycles progresses (130). ) and the data corresponding to the setting of the data switches in mode 2 are added to the register so

  the depth limit is updated (132).

  The new number of cycles is then displayed on the device 48, and the control returns to the loop which causes the operation of the EDM machine (120), the driving device advancing so that it

executes the second machining step.

  If we assume that the crossing is not

  performed, the operation is repeated until the name

  At this point, and in the absence of a crossing, this is an indication of

  (134) since a crossing must have been observed

mally.

  On the other hand, when a crossing has been

  tected during one of the machining steps, the control immediately switches to the recoil of the electrodes and to a new advance thereof on the support (136) A final machining step is then executed (138) and, at the end of this

  a signal (140) is transmitted and indicates that the

  total smelter has been reached, this operation

  the end of the cycle (142), the end of the work being then indicated

  (144) The final complete machining step after

  tection of the crossing must ensure a practical crossing

  only simultaneous of all the holes, without exceeding.

  In the case of mode 2 during the initial advance to the set initial depth limit, a fault signal is indicated when a traverse (110) occurs during such an initial advance When a fault is indicated 1 the main control of enslavement is

immediately stopped.

  It will be noted in FIG. 3 that a mode 1 operation (146) can be integrated with the mode 2 operation, and this operation takes place before the mode 2 operation is executed. However, in most cases, one either of the modes only is chosen

for a given operation.

  The above description relates to a device

  electronic depth adjustment intended to be

  associated with an electro-erosion machining machine.

  The description relates to an advantageous embodiment

  from the point of view of construction and operation.

  However, the invention is not limited to this particular embodiment. For example, in the case of the machining of holes that open, this embodiment implements an additional complete cycle after the detection of a traversal. It is not essential that such an operation is always performed. In other words, the detection of a crossing simply creates a decision point at which particular operations are performed.

  additional decisions must be made.

  are the execution of additional sub-cycles,

  the execution of an additional predetermined step of

  swimming other than the chosen sub-cycle, or the complete stop

  of the machining operation These possibilities are simply

  In addition, although the described embodiment implements a new advance of the electrodes, it is not essential that a device providing this

  new advance is incorporated in all cases.

  The above description therefore relates to a

  electronic depth control apparatus for operating in cooperation with an EDM machine The apparatus according to the invention allows a very precise adjustment of the depth of the machined holes

  in the case of blind holes as well as through holes.

  It is understood that the invention has been described and shown only as a preferred example and that we can bring any technical equivalence in its constituent elements without leaving out

of its frame.

Claims (7)

  1 Machining depth-adjusting apparatus for an EDM machine, when machining at least one hole in a workpiece with at least one electrode advancing to the workpiece, said machine having a main control (10) having a control device (24) for operating the control and including the setting of the advance of   minus one electrode, said apparatus being characterized -   in that it is associated with the main control (10) and in that it comprises its own control device   (28) and a device (32) for transmitting data   this last control device (28), these data   arising out of the advance of at least one   trode (14), the latter control device (28) transmitting   putting data itself to the controller (24) of the main control = -   2 Apparatus according to claim 1, characterized in that the control device (24) of the control   (10) comprises a microprocessor, the device   control unit (28) of the depth adjuster   deur (12) comprises a microprocessor programmed to execute two sets of operating instructions relating to the depth adjustment of at least one hole,   and the device for transmitting data   door data entry devices that can   chosen -and which are intended to convey   selected from the microprocessor (28) of the depth control apparatus, these data relating to the advance of at least one electrode (14), the device   introduction of data that can be chosen   taking a device (40, 42) for selecting which set of operating instructions to execute. Apparatus according to claim 2, characterized in that the data input device which can be selected comprises a device (38) for selecting a desired initial depth limit,   a device (40, 42) for selecting a desired step of   and a device (44) for selecting a desired number   machining step, and in that a first of the sets of   tructions, when selected, causes an initial advance of the electrode (14) to the desired initial depth limit and then its successive advance of desired machining steps to the desired number of said steps, per initial loading. of a register by data corresponding to the desired initial limit of   depth then, when at least one electrode is   at the desired initial depth limit, by updating the contents of the register with the value of a desired machining step and, after the end of each successive step of machining, by content day   of the register using the value of a desired step of   until the register has been updated a number of times equal to the desired number of machining steps chosen -   4 Apparatus according to claim 3, characterized in that it comprises a device for advancing again the electrode (14) at least with respect to a support (16) of electrodes, and the main control   (10) causes a new advance of at least one   trode (14) on the support (16) when the predetermined limit   completed depth was reached then successively between the machining steps.   Apparatus according to claim 2, characterized   in that it comprises a device for detecting   poured from one or more electrodes (14) through the workpiece (20) during machining, and that the device   introduction of data that can be chosen   carries a device (38) for selecting an initial limit   desired depth of depth and a device (40, 42) for selecting a desired machining step, and in that a first set of instructions, when selected, causes the initial advance of at least one electrode (14) at   initial desired depth limit and then the repeated advance   successive steps of machining until the   of the electrode at least be detected by the   positive crossing detection.   Apparatus according to claim 5, characterized   in that it comprises a device sensitive to the detection   passing through the traversing detection device during the advance of at least one electrode to the desired initial depth limit and for transmitting a signal indicating that a traverse has been made during the advance of at least one an electrode to   the desired initial depth limit.   7 Apparatus according to claim 5, characterized in that it comprises a device sensitive to the absence of crossing detection by the traversing detection device both during the advance of at least one electrode to the desired limit depth and when   the electrode has advanced for the desired number of steps   This device is intended to transmit a signal   indicating that the crossing was not made or   the advance of at least one electrode to the initial limit   desired depth or during the advance during the desired number of machining steps.   8 Apparatus according to claim 2, characterized in that it comprises a device for advancing again at least one electrode (14) on a support (16), and comprising a traversing detection device   of at least one electrode through the workpiece during the machining   in that the data input device which can be selected comprises a device (38) for selecting a desired initial depth limit, a device (40) for selecting a first desired machining step, a device (42) for selecting a second desired machining step, and a device (44) for selecting a desired number of machining steps, in that one of the instruction sets, when it is chosen, ensures the modification of the desired initial depth limit, the first desired machining step and the desired number of machining steps so that at least one electrode initially advances to the desired initial depth limit and then advances during a series of desired first machining steps equal to the desired chosen number of machining steps, a new advance of the electrodes on their support being   realized once the predetermined limit of depth   has been reached and subsequently between the   in that the other set of instructions, when chosen, causes the initial advance of at least one electrode to the desired initial depth limit and then the repeated advance in the desired second successive steps of machining until the crossing of at least one electrode is detected by the traversing detection device or until the total number of steps machining has been performed.   9 Apparatus according to claim 8, characterized in that the device (44) for selecting a desired number of machining steps comprises a first device (44 a) for selecting a desired number of machining steps associated with the device (40) for selecting a first desired machining step and a second device (44b) for selecting a desired number of associated machining steps   the device (42) for selecting a second desired step.   the first and the second selection device   a desired number of machining steps being selected   depending on the selected instruction set -   Apparatus according to claim 2, characterized   in that it comprises a device for selecting the dis-   positive introduction of data that can be chosen   according to the time or distance parameter or a first or higher-order derivative of a   such a parameter, such as speed or acceleration.