JP2019130629A - Wire residual quantity detection device - Google Patents

Abstract

A wire electric discharge machine detects a remaining amount of a wire electrode wound around a wire bobbin with high accuracy. A wire remaining amount is detected based on means for detecting a rotation speed of a wire bobbin, a detected rotation speed of the wire bobbin, and a feed speed of the wire electrode by a wire sending means. A winding diameter calculator 81 for calculating the winding diameter of the wire electrode in the wire bobbin 31 and a relationship between the winding diameter and the remaining amount obtained based on the result of actually measuring the winding diameter and the remaining amount of the wire electrode 2 in the wire bobbin 31. A storage unit 86 for storing the specifications relating to the winding diameter of the wire bobbin 31 and the wire electrode 2 and an input unit 85 for inputting the specifications of the wire bobbin 31 and the wire electrode 2 used for electric discharge machining. Using the relationship stored in the storage unit 86 in association with the above specification, the winding diameter calculated by the winding diameter calculator 81 is applied to the wire diameter forming the relationship. And a wire remaining amount detecting portion 82 for determining the remaining amount of Umate wire electrode 2. [Selection] Figure 2

Description

  The present invention relates to a remaining wire detection device for detecting the amount of wire electrodes remaining on a wire bobbin in a wire electric discharge machining device.

  In a general wire electrical discharge machining apparatus, a wire bobbin that winds and holds a wire electrode is fed out at a predetermined speed to supply a new unused wire electrode that is not used for machining to the machining gap. By properly grasping when to replace the wire bobbin with a new one, in order to prevent the wire electrode from being broken during processing or to use the wire electrode of the wire bobbin without waste, the wire in the wire bobbin It is required to detect the remaining amount of the electrode as accurately as possible.

For example, in Patent Document 1, page 3, right column, line 16 to column 47, line 47 and the like measure the number of revolutions of the wire bobbin and the number of revolutions of the reference roller of the wire travel system, calculate the delivery length, and calculate the wire bobbin. There is shown an apparatus for calculating the winding diameter of a wire bobbin from the number of rotations and the delivery length and calculating the remaining amount of the wire bobbin based on the determined winding diameter.
Further, in Patent Document 2, the third column, the left column, line 22 to the right column, the right column, line 29, etc., the shaft diameter / width of the wire bobbin, the rotational speed (traveling speed) of the tension roller, the reel rotational speed, and the wire An apparatus for measuring the wire remaining amount from the diameter is shown.

Japanese Patent No. 2736544 Utility Model Registration No. 2510109

  However, in the conventional wire remaining amount detecting apparatus as described above, there is a room for further increasing the accuracy of wire remaining amount detection. Further, if the detection accuracy is to be increased, the configuration and operation of the remaining wire amount detection device become difficult.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wire remaining amount detecting device that can detect the remaining amount of wire electrodes in a wire bobbin relatively easily, safely, and with higher accuracy.

The wire remaining amount detecting device according to the present invention is:
In a wire electric discharge machining apparatus including a wire bobbin that winds and holds a wire electrode, and a wire feeding unit that pulls out the wire electrode from the wire bobbin and continuously sends it to a workpiece, the wire electrode wound around the wire bobbin A wire remaining amount detecting device for detecting a remaining amount,
A rotational speed detecting means for detecting the rotational speed of the wire bobbin;
A winding diameter calculation unit that calculates the winding diameter of the wire electrode in the wire bobbin based on the rotation speed of the wire bobbin detected by the rotation speed detection means and the feeding speed of the wire electrode by the wire delivery means;
A storage unit for storing the relationship between the winding diameter and the remaining amount obtained based on the results of actual measurement of the winding diameter and the remaining amount of the wire electrode in the wire bobbin in association with the specifications related to the winding diameter of the wire bobbin and the wire electrode. When,
An input unit for inputting the above specifications of the wire bobbin and wire electrode used for electric discharge machining,
Using the above relationship stored in the storage unit in association with the specifications input to the input unit, the wire winding diameter constituting the relationship is applied to the winding diameter calculated by the winding diameter calculation unit, and the remaining amount of the wire electrode Wire remaining amount detection unit for obtaining,
Is provided.

  More specifically, the specifications relating to the winding diameter of the wire bobbin and the wire electrode are more specifically the body diameter and inner width of the wire bobbin (the width of the body portion around which the wire electrode between the pair of left and right wings is wound) , And the outer diameter of the wire electrode.

In a preferred embodiment of the present invention,
Wire speed detection means for detecting the feed speed of the wire electrode by the wire delivery means is further provided,
The winding diameter calculation unit uses the feed speed detected by the wire speed detecting means as the feed speed of the wire electrode.

  According to the wire remaining amount detecting device of the present invention, since the wire remaining amount is obtained using the relationship between the actually measured wire winding diameter and the wire remaining amount, the wire remaining amount in the wire bobbin can be relatively easily and safely. It can be obtained with high accuracy.

The schematic block diagram which shows the wire electric discharge machining apparatus provided with the wire residual amount detection apparatus by one Embodiment of this invention. The block diagram which shows the wire residual amount detection apparatus by one Embodiment of this invention. Partially cutaway side view showing a part of the wire electric discharge machining apparatus The perspective view which shows the wire bobbin which can be used for a wire electrical discharge machining apparatus A graph showing an example of the relationship between the wire winding diameter and the remaining wire amount in a wire bobbin The graph which shows the mode of the change over time of wire tension, wire speed, and wire winding diameter in the above-mentioned wire electric discharge machining device The graph which shows the waveform of the pulse signal which a proximity sensor emits in the said wire electric discharge machining apparatus

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a wire electric discharge machining apparatus including a wire remaining amount detection apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the remaining wire amount detection device according to one embodiment of the present invention. First, the overall configuration of the wire electric discharge machine will be described with reference to FIG.

  The wire electrical discharge machining apparatus shown in FIG. 1 includes an automatic connection device 1, a supply mechanism 30 for continuously supplying a wire electrode 2 to a machining site of the workpiece 3, and a used wire electrode 2 for the workpiece 3. And a discharge mechanism 70 for recovering from the processing site. The automatic connection device 1 is means for automatically inserting the wire electrode 2 into the prepared hole 4 formed in the workpiece 3. The unused wire electrode 2 is wound and held on the wire bobbin 31. The wire electrode 2 drawn out from the wire bobbin 31 is sent in the order of the supply mechanism 30, the automatic wire connection device 1, and the discharge mechanism 70.

  The supply mechanism 30 continuously supplies the unused wire electrode 2 to the processing site. The supply mechanism 30 includes a reel 32 having a brake motor 40 that applies a load in a direction against the pulling of the wire electrode 2 to the wire bobbin 31 so that a so-called back tension is applied to the wire electrode 2, and fluctuations in the tension of the wire electrode 2. A servo pulley 33 that prevents the wire electrode 2 from being pulled out and sent to the wire bobbin 31, and a tension roller, a feed roller 20 that applies tension, a break switch 34 that detects a break in the wire electrode 2, and a strain gauge. A tension detector 35 for detecting the tension of the wire electrode 2. The wire electrode 2 drawn out from the wire bobbin 31 reaches the automatic wire connection device 1 through the servo pulley 33 and the delivery roller 20.

  The feed roller 20 that constitutes the wire feed unit includes a drive roller 22 that rotates forward and backward by a servo motor 21 and pinch rollers 23 and 24 that follow the drive roller 22 and press the wire electrode 2. As an example, the roller portion of the pinch roller 23 is made of ceramic, and the roller portion of the pinch roller 24 is made of rubber.

  The automatic connection device 1 includes a pair of energizing electrodes 41 and 42 that supply a heating current to the wire electrode 2 to which tension is applied, and a guide pipe 10 that is provided between the pair of energizing electrodes 41 and 42 and guides the wire electrode 2. And a fluid supply device 16 that is provided on the supply mechanism 30 side of the guide pipe 10 and supplies fluid into the guide pipe 10.

  The energizing electrode 41 is also used as a forward / reverse roller for feeding out or winding up the wire electrode 2. That is, the energizing electrode 41 formed in a roller shape is rotated in the forward and reverse directions by the connected motor 45 and sandwiches the wire electrode 2 with the pinch roller 43 disposed opposite to the wire electrode 2 in the forward and reverse direction. send. On the other hand, the energizing electrode 42 holds the wire electrode 2 between the pinch roller 44 disposed opposite to the energizing electrode 42. The energizing electrode 41 and the pinch roller 43 are disposed on the supply mechanism 30 side, and the energizing electrode 42 and the pinch roller 44 are disposed on the discharge mechanism 70 side with the guide pipe 10 interposed therebetween.

  The pair of energizing electrodes 41 and 42 is connected to an energizing power source 47 and supplies a heating current to the wire electrode 2. At this time, the wire electrode 2 is given a tension that is weaker than the tension during processing, so as not to break the wire electrode 2. The heating current and tension are set according to the wire diameter and material of the wire electrode 2. The heating current supplied from the energizing power source 47 can be changed by changing the resistance value of the energizing power source 47. Further, the tension of the wire electrode 2 between the pair of energizing electrodes 41 and 42 can be changed by changing the torque of the servo motor 21.

  The guide pipe 10 is disposed between the energizing electrode 41 and an upper wire guide 62 described later. The guide pipe 10 is moved up and down by a lifting device 15 operated by an actuator. When the automatic connection is not performed, the guide pipe 10 is raised to the upper limit position and stopped. When the wire electrode 2 is inserted into the prepared hole 4, the guide pipe 10 descends to at least a position immediately above the upper wire guide 62 in accordance with the feeding of the wire electrode 2, and guides the wire electrode 2 to the upper wire guide 62. To do. The guide pipe 10 is attached to a vertical movement member (not shown) supported on the main body side of the automatic connection device 1 by tightening with a cap 14.

  The fluid supply device 16 is, for example, a compressed air supply device, and includes a compressed air supply source such as an air compressor (not shown) and a regulator. In this configuration, the fluid supplied from the fluid supply device 16 is compressed air. The fluid supply device 16 adjusts the high-pressure compressed air of the compressed air supply source to a predetermined pressure with a regulator during automatic connection, and supplies the compressed air into the guide pipe 10. In this way, the fluid supply device 16 generates a downward airflow directed toward the discharge mechanism 70 to send the wire electrode 2 downward along the traveling path, that is, toward the discharge mechanism 70 and to impart straightness to the wire electrode 2.

  The automatic connection device 1 further includes a tip processing device 50 that cuts and discards the rough tip of the wire electrode 2. The tip processing device 50 holds a cutting device 51 that cuts the wire electrode 2, a disposal box 52 that collects the cutting pieces of the wire electrode 2 that are no longer needed after being cut by the cutting device 51, and the cutting pieces of the wire electrode 2. Then, a clamp unit 53 for conveying to the disposal box 52 and a tip detector 54 for detecting the tip of the wire electrode 2 are included.

  In the wire electric discharge machining apparatus, an upper guide assembly 60 and a lower guide assembly 61 are provided. The upper guide assembly 60 provided on the upper side of the workpiece 3, that is, on the supply mechanism 30 side is a unit in which an upper wire guide 62, an upper energizing body 63, and a machining liquid jet nozzle 64 are integrally incorporated in a housing. is there. The lower guide assembly 61 provided on the lower side of the workpiece 3, that is, on the discharge mechanism 70 side, includes a lower wire guide (not shown), a lower energizer, and a machining liquid jet nozzle that are integrally incorporated in the housing. It is a unit. The upper wire guide 62 and the lower wire guide position and guide the wire electrode 2 at a position as close as possible to the workpiece 3. The upper energizing body 63 and the lower energizing body supply a current for electric discharge machining to the wire electrode 2.

  Further, in this wire electric discharge machining apparatus, a high-pressure machining fluid supply device 65 that supplies a high-pressure electrical discharge machining fluid to the chambers of the machining fluid jet nozzle 64 of the upper guide assembly 60 and the machining fluid jet nozzle of the lower guide assembly 61 is provided. Is provided. The high-pressure machining fluid supply device 65 selectively supplies high-pressure machining fluid to the chamber of the machining fluid jet nozzle as necessary. The machining liquid jet of a predetermined pressure stored in the chamber is jetted coaxially with respect to the travel path axis of the wire electrode 2 from the machining liquid jet nozzle toward the machining gap, that is, the pilot hole 4 of the workpiece 3. Thus, the wire electrode 2 is inserted into the prepared hole 4 while being restrained by the machining liquid jet.

  The discharge mechanism 70 collects the used wire electrode 2 that has been consumed by the processing of the workpiece 3 from the processing site. The discharge mechanism 70 provides an offset to the traveling path of the wire electrode 2 that is vertically stretched on the workpiece 3 and also changes the traveling direction of the wire electrode 2 that is fed out, and the wire electrode 2. A conveying device 72 that conveys the wire electrode 2, a winding roller 73 that winds up the wire electrode 2, and a bucket 74 that collects the used wire electrode 2.

  In the wire electric discharge machining apparatus having the above-described configuration, machining between the wire electrode 2 fed from the above-described upper current-carrying body 63 and the lower current-carrying body and the workpiece 3 fed via a current-carrying body not shown. In the gap (prepared hole 4), an electric discharge is generated in the machining liquid, whereby the workpiece 3 is machined. At that time, the table 3 (not shown) on which the workpiece 3 is placed is moved relative to the wire electrode 2 so that the workpiece 3 can be processed into a desired shape.

  Note that when the stretched wire electrode 2 is intentionally cut and newly inserted into the machining start hole of the workpiece 3, or when the wire electrode 2 is accidentally disconnected, the automatic connection device 1 Thus, the wire electrode 2 is automatically connected. For the automatic connection by the automatic connection device 1, a conventionally known method shown in, for example, Japanese Patent Application Laid-Open No. 2006-221654 can be applied, and the detailed description thereof is omitted.

  Next, a wire remaining amount detection apparatus according to an embodiment of the present invention shown in FIG. 2 will be described. In FIG. 2, the electrical configuration is shown as a block diagram. In addition to the block diagram, FIG. 2 shows a proximity sensor 38, which will be described later, in addition to the same servo motor 21, drive roller 22, pinch rollers 23 and 24, and wire bobbin 31 shown in FIG.

  FIG. 3 shows a configuration around the wire bobbin 31. As shown in the figure, the wire bobbin 31 is loaded on a reel 32 at the tip of a rotating shaft that passes through the bobbin holding plate 36 and is rotatably held. As described above, the wire electrode 2 is formed by the reel 32 to which the brake motor 40 is directly connected. Is driven to rotate at a predetermined torque in a direction opposite to the direction in which it is fed out. Therefore, when there is no load on the wire bobbin 31, the wire bobbin 31 rotates in reverse at a predetermined rotational speed. However, when the wire electrode 2 is fed toward the machining gap by the feed roller 20, the wire bobbin 31 has a predetermined A braking force is generated, and a back tension is applied to the wire electrode 2. A proximity sensor detection plate 37 that rotates integrally with the reel 32 is fixed to the reel 32 coaxially with the rotation axis of the reel 32. The proximity sensor detection plate 37 is a disc in which, for example, 15 through holes are evenly provided in the circumferential direction. A proximity sensor 38 is attached to the bobbin holding plate 36 at a position facing the through hole of the proximity sensor detection plate 37. The proximity sensor 38 is, for example, an inductive type or a capacitance type, and emits a pulse signal each time the through-hole provided in the proximity sensor detection plate 37 passes the facing position, so that the wire bobbin 31 rotates once. Each time, 15 pulse signals are output. A mechanical bobbin brake 39 is attached so as to face the through hole with the bobbin holding plate 36 in between. A wire bobbin reversely rotated by a brake motor 40 when a stopper is inserted into the through hole and there is no load. 31 can be temporarily non-rotatably fixed as required.

  Returning to FIG. 2 and continuing the description, the wire remaining amount detecting device basically includes the proximity sensor 38, a rotation speed calculator 80 to which the pulse signal S1 output from the proximity sensor 38 is input, and a rotation speed calculator. 80, a winding diameter calculator 81 to which a rotational speed signal S2 output from the input terminal 80 is input, a wire calculator 82 to which a winding diameter signal S3 output from the winding diameter calculator 81 is input, and a wire remainder output from the wire calculator 82. It comprises a display device 83 to which the quantity signal S4 is input, a speed detector 84 to which the encoder pulse S5 of the servo motor 21 that rotates the drive roller 22 is input, an input unit 85, and a storage unit 86. The speed detector 84 detects the feed speed of the wire electrode 2 based on the encoder pulse S5 and outputs a wire feed speed signal S6. The wire feed speed signal S6 is input to the winding diameter calculator 81 and a length measuring device 87 described later.

  2, the length measuring device 87 connected to the storage unit 86, the rotation speed signal S2 output from the rotation speed calculator 80, and the winding diameter signal S3 output from the winding diameter calculator 81 are input. An empty discriminator 88 and a motor control device 89 to which a bobbin empty signal S7 output from the empty discriminator 88 is input are provided.

  In general, there are a plurality of standards for the wire bobbin 31, and one of the wire bobbins 31 suitable for the machining is selected and used in the electric discharge machining. Table 1 shows a dimension example of each part of the wire bobbin 31 in each of the plurality of standards. Note that the dimensions such as the diameter D defined by each standard are the dimensions of the portion shown in FIG.

  In addition, as the wire electrode 2 wound around the wire bobbin 31, for example, one type of wire electrode 2 is selected from the wire electrodes 2 having outer diameters φ different from 0.05 mm, 0.1 mm, 0.2 mm, etc. used. When the wire electrode 2 is wound around the wire bobbin 31, the relationship between the length of the wire electrode 2 being wound (remaining wire amount) and the wound outer diameter (wire winding diameter) of the wire electrode 2 is as follows: It is uniquely determined by the body diameter d of 31, the inner width W of the wire bobbin 31, and the outer diameter φ of the wire electrode 2. In the present embodiment, the trunk diameter d and the inner width W are specifications of the wire bobbin 31 that are involved in the wire winding diameter, and the outer diameter φ is the specification of the wire electrode 2 that is involved in the wire winding diameter.

  The storage unit 86 shown in FIG. 2 stores the relationship between the wire winding diameter R and the wire remaining amount S for each specification of the wire bobbin 31 and the wire electrode 2, measured as described later, in association with the specification. ing. FIG. 5 shows two examples of the relationship between the wire winding diameter R and the remaining wire amount S as α and β, respectively.

  Next, with reference to FIG. 2, detection of the remaining amount of wire performed during wire electric discharge machining will be described. Prior to starting the wire electric discharge machining, specifications of the wire bobbin 31 and the wire electrode 2 to be used are input to the input unit 85. This input is made by inputting numerical values of the body diameter d, the inner width W of the wire bobbin 31 and the outer diameter φ of the wire electrode 2. Alternatively, since the body diameter d and the inner width W of the wire bobbin 31 are determined for each standard of the wire bobbin 31 as shown in Table 1, the specification of the wire bobbin 31 is input indirectly by inputting this standard. May be made. The input specifications of the wire bobbin 31 and the wire electrode 2 are input to the wire calculator 82 via the winding diameter calculator 81.

  When wire electric discharge machining is performed, the wire roller 2 is pulled out from the wire bobbin 31 at a substantially constant speed by the drive roller 22 that constitutes the wire delivery unit. Thereby, since the wire bobbin 31 rotates, the proximity sensor 38 outputs the pulse signal S1 described above every moment. The rotational speed calculator 80 detects the rotational speed, that is, the rotational speed of the wire bobbin 31 in a predetermined detection cycle based on the pulse signal S1. As described above, in the present embodiment, the proximity sensor 38 and the rotation speed calculator 80 constitute a rotation speed detection unit that detects the rotation speed of the wire bobbin 31. The rotation speed calculator 80 outputs a rotation speed signal S 2 indicating the detected rotation speed of the wire bobbin 31, and the rotation speed signal S 2 is input to the winding diameter calculator 81.

Further, when wire electric discharge machining is performed, the encoder pulse S5 of the servo motor 21 is input to the speed detector 84. The speed detector 84 detects the feed speed of the wire electrode 2 based on the encoder pulse S5, and outputs a wire feed speed signal S6 indicating the detected speed. The wire feed speed signal S6 is also input to the winding diameter calculator 81. The winding diameter calculator 81 is based on the wire feed speed indicated by the wire feed speed signal S6 and the wire bobbin rotation speed indicated by the rotation speed signal S2, and the winding outer diameter of the wire electrode 2 in the wire bobbin 31, that is, the wire winding diameter. Is calculated. This calculation is performed by, for example, the following equation. As an example, the wire feed speed is about 10 m / min≈167 mm / s.
Wire winding diameter (mm) =
Wire feed speed (mm / s) / {π · Wire bobbin rotation speed (times / s)} (1)

  The winding diameter calculator 81 outputs a winding diameter signal S3 indicating the wire winding diameter obtained as described above, and this winding diameter signal S3 is input to the wire calculator 82. The wire computing unit 82 as the wire remaining amount detection unit includes the wire winding diameter indicated by the winding diameter signal S3, the wire winding diameter R and the wire remaining amount for each specification of the wire bobbin 31 and the wire electrode 2 stored in the storage unit 86. Based on the relationship with S, the wire remaining amount S in the wire bobbin 31 is obtained.

  That is, the wire computing unit 82 is based on the specifications of the wire bobbin 31 and the wire electrode 2 input to the input unit 85 before starting the wire electric discharge machining, and is associated with this specification and stored in the storage unit 86. The relationship between the diameter R and the remaining wire amount S is read from the storage unit 86, and a signal S8 indicating this relationship is captured. Then, the wire computing unit 82 applies the wire winding diameter indicated by the winding diameter signal S3 to the wire winding diameter R in the above relationship to obtain the remaining wire amount S. The wire computing unit 82 outputs a wire remaining amount signal S4 indicating the obtained wire remaining amount S, and this wire remaining amount signal S4 is input to the display device 83. For example, the display device 83 including a liquid crystal display device displays the wire remaining amount S indicated by the wire remaining amount signal S4 on the display screen. An operator or the like who is performing wire electric discharge machining can know how long the wire electrode 2 remains in the wire bobbin 31 by looking at the display on the display device 83.

  As described above, according to the wire remaining amount detecting device of this embodiment, the wire remaining amount is obtained using the relationship between the actually measured wire winding diameter R and the wire remaining amount S. The quantity can be obtained with high accuracy.

  In the display device 83 shown in FIG. 2, the wire remaining amount may be simply indicated by the length of the wire electrode 2 remaining on the wire bobbin 31, or the length of the remaining wire electrode 2 and speed detection. From the wire feed speed detected by the device 84, a wire electric discharge machining time that can be continued thereafter may be obtained, and the machining time may be indicated on the display device 83 as the remaining wire amount. Further, such a processing time and the length of the wire electrode 2 remaining on the wire bobbin 31 may be indicated on the display device 83.

  Here, the point which calculates | requires the relationship between the wire winding diameter R and the wire residual amount S as shown in FIG. 5 based on those measured values is demonstrated. When obtaining the above relationship for a wire bobbin 31 of a certain specification, a wire bobbin 31 in which the entire winding length of the wire electrode 2 is accurately known is prepared. Although the wire electric discharge machining is not performed, the wire electrode 2 is pulled out from the wire bobbin 31 by the driving roller 22 as in the case of the wire electric discharge machining. At this time, the speed detector 84 outputs a wire feed speed signal S6 indicating the feed speed of the wire electrode 2 based on the encoder pulse S5 of the servo motor 21 in the same manner as described above.

  The wire feed speed signal S6 is input to the length measuring device 87. The length measuring device 87 integrates the wire feed speed signal S6, for example, or accumulates and records the wire feed speed signal S6 to feed rollers. The length of the wire electrode 2 drawn from the wire bobbin 31 is obtained by directly obtaining from the number of rotations of 20. Then, the length measuring device 87 obtains the remaining wire amount S remaining in the wire bobbin 31 by subtracting the length of the drawn wire electrode 2 from the entire winding length of the wire electrode 2. Further, the winding diameter signal S3 output from the winding diameter calculator 81 is input to the length measuring device 87 as in the case of wire electric discharge machining. The length measuring device 87 samples the signal indicating the wire remaining amount S and the winding diameter signal S3 at an appropriate time interval to obtain a relationship between the wire winding diameter R and the wire remaining amount S, and a signal indicating this relationship. S9 is input to the storage unit 86. This relationship is stored in the storage unit 86 in association with the specifications of the wire bobbin 31 and the wire electrode 2 used to obtain the relationship.

  Note that the relationships α and β between the wire winding diameter R and the wire remaining amount S in FIG. 5 are obtained in two cases where the specifications of the wire bobbin 31 and the wire electrode 2 are different from each other. If the specifications of the wire bobbin 31 and the wire electrode 2 are constant, basically only one such relationship is required.

  However, even when the above specifications are constant, if the wire winding diameter R and the wire remaining amount S are measured a plurality of times, a plurality of relationships between the wire winding diameter R and the wire remaining amount S are obtained due to measurement errors and the like. It can be done. In such a case, an average relationship between them may be obtained from the plurality of relationships and stored in the storage unit 86. Alternatively, only one of the plurality of relationships may be selected, and the selected relationship may be stored in the storage unit 86. However, unless the remaining length of the wire electrode 2 is directly detected, it is impossible to avoid the occurrence of a calculation error, and in any case, the remaining amount of wire must be estimated in consideration of safety. In practice, the actual measurement error as described above is not particularly problematic. That is, although it depends on the quality of the wire bobbin product, there is little demand for registering data for compensating the calculated wire remaining amount value using the plurality of wire bobbins 31. Rather, even if the actual measurement values of a large number of wire bobbins 31 are accumulated, the uncertainty of the calculation of the remaining amount of wire cannot be reduced, but the burden of collecting data is increased, and the wire electrode 2 is made more Since only a large amount is consumed, it is desirable to register only the data of one wire bobbin 31.

As described above, when storing one selected relationship in the storage unit 86, it is desirable to pay attention to the following points. Hereinafter, the relationship α and β in FIG. 5 will be described as an example. Before the wire bobbin 31 is used, it is assumed that the wire remaining amount in the wire bobbin 31 is S ₀ and the wire winding diameter is R ₀ . Wire remaining Also in the wire bobbin 31 when the minimum value of the wire winding diameter has decreased to R _1, if the relationship α is selected in S _1, if the relationship β is selected to be S _2. Then, when the remaining amount of the wire becomes a considerably small set amount, it is assumed that there is a demand to temporarily suspend the wire electric discharge machining operation and replace the wire bobbin 31 holding the wire electrode 2 with another new one. .

Although the specifications of the wire bobbin 31 and the wire electrode 2 are constant, the fact that the two relationships α and β are required is likely to be an intermediate relationship between α and β. If fact was the case, the wire remaining when the wire winding diameter is a value near the minimum value R _1, if the relationship α is selected fewer sought than the actual wire remaining relation β When is selected, it is required to be larger than the actual wire remaining amount. Therefore, if importance is attached to the safety of avoiding a situation in which the wire electric discharge machining operation is continued without replacing the wire bobbin 31 until the remaining amount of the wire electrode 2 in the wire bobbin 31 becomes 0 (zero). It can be said that it is desirable to select the relationship α in which the remaining wire amount is estimated to be smaller than the diameter, that is, the relationship α in the above example.

  In the present embodiment, the speed measured by the speed detector 84 is used as the wire feed speed for the wire diameter calculator 81 of FIG. 2 to calculate the wire winding diameter. When it is input as one of machining conditions (parameters) from the control unit of the unit 85 or the wire electric discharge machining apparatus, the input value may be used as it is as the wire feed speed.

  In the present embodiment, the empty discriminator 88 shown in FIG. 2 is used to detect that the wire bobbin 31 is in an empty state, that is, no wire electrode 2 remains at the time of wire electric discharge machining. Hereinafter, this empty state detection will be described.

  6 shows the wire winding diameter indicated by the winding diameter signal S3 output from the winding diameter calculator 81 in FIG. 2, and the wire feed speed (wire speed) indicated by the wire feed speed signal S6 output from the speed detector 84 in FIG. ) And changes in the tension (wire tension) of the wire electrode 2 detected by the tension detector 35 in FIG. 1 over time. The empty discriminator 88 receives the winding diameter signal S3 and the rotational speed signal S2 output from the rotational speed calculator 80.

  In the wire electric discharge machining apparatus, it is necessary to arrange the wire electrode 2 in a tensioned state in the machining gap of the workpiece 3, and therefore, generally from the feeding roller 20 that also serves as the tension roller shown in FIG. A means for holding the wire electrode 2 is provided. On the other hand, the reel 32 to which the wire bobbin 31 is mounted is combined with the brake motor 40 as described above, so that a predetermined back tension is applied to the wire electrode 2 between the wire bobbin 31 and the delivery roller 20. Yes. Since the wire electrode 2 running between the reel 32 and the take-up roller 20 vibrates slightly, it is detected by the tension detector 35, for example, as shown in the range from time 0 to T1 in FIG. Although the tension includes a minute vibration component, a substantially constant tension is generated in the wire electrode 2 in the machining gap.

  Here, if the wire bobbin 31 is empty at time T1 shown in FIG. 6, that is, the wire electrode 2 is not wound at all, then the wire winding diameter is marked with “Q” in FIG. As shown by the circles, a sudden drop occurs. Hereinafter, this point will be described in detail. When the end of the wire electrode 2 wound and held on the wire bobbin 1 is separated from the wire bobbin 31 at time T1, the wire bobbin 31 has a rotation direction (positive direction) when the wire electrode 2 is pulled out by the brake motor 40. Since a force in the reverse direction acts, the wire bobbin 31 stops rotating instantaneously and then rotates in the reverse direction.

  FIG. 7 shows the waveform of the pulse signal S1 from the proximity sensor 38 at this time. As shown in the figure, the pulse signal S1 does not rise during the period in which the wire bobbin 31 is instantaneously stopped as described above, and after this period has passed, the wire bobbin 31 is rotated in the reverse direction by the brake motor 40. Along with it, it comes up again. In this example, the reverse rotation of the wire bobbin 31 is faster than the rotation speed of the forward rotation when the wire electrode 2 is pulled out through the acceleration period, so that the pulse width and period of the pulse signal S1 are finally This is shorter than that in the period before the rotation stop.

  When the rotation of the wire bobbin 31 stops for a moment and the number of pulse signals S1 during a predetermined calculation period becomes extremely small, the detected rotation speed of the wire bobbin suddenly becomes remarkably slow. Therefore, the feed speed of the feed roller 20 and the wire bobbin 31 The calculated winding diameter calculated with the rotational speed of the shaft once increases. In the embodiment, since the winding diameter is calculated with a predetermined calculation period of about 1 second to several seconds in practice, the winding diameter slightly increases at time T1 in the graph shown in FIG. However, if the calculation cycle is shortened to the limit, the rotation speed of the wire bobbin 31 during the calculation period when the rotation of the wire bobbin 31 stops momentarily approaches zero to the limit. The phenomenon of increase in the diameter of the roll appears more clearly. Immediately after that, when the wire bobbin 31 starts reverse rotation by the braking force and increases the rotation speed, the detected rotation speed of the wire bobbin 31 increases, and this time, the winding diameter is calculated to be rapidly reduced. Since the predetermined calculation cycle is 1 second to several seconds, when compared with the generation degree of the pulse signal S in FIG. 7, there is a step on the line indicating the winding diameter at the point Q for a while after the time T1 shown in FIG. Arise. Therefore, the rapid decrease in the wire winding diameter shown in FIG. 6 is due to the reverse rotation of the wire bobbin 31 at a high speed immediately after the wire bobbin 31 stops rotating instantaneously. The transition at a slightly lower value following this rapid decrease is due to the fact that the reverse rotation of the wire bobbin 31 has shifted to a constant speed.

  The empty discriminator 88 discriminates that the wire bobbin 31 is in an empty state when it detects a rapid decrease in the wire winding diameter from the input winding diameter signal S3. Specifically, for example, by comparing the winding diameter newly calculated every calculation cycle of 1 second to several seconds with the previously calculated winding diameter, the phenomenon that the winding diameter increases at time T1 and the subsequent Q point A decrease in the winding diameter can be detected. More specifically, when the winding diameter calculated later is larger than the previously calculated winding diameter, it is determined that the wire bobbin 31 is not present in the wire bobbin 31 and the rotation of the wire bobbin 31 stops momentarily at time T1. After the next calculation period, the wire bobbin has already started to reversely rotate at a high speed exceeding the normal rotation speed, so that a rapid decrease in the winding diameter can be detected from the rapid increase in the pulse signal S1. . When it is attempted to determine that the wire bobbin 31 has been emptied only by the phenomenon of a sudden decrease in the wire winding diameter, for example, the difference between the winding diameter calculated before and the winding diameter calculated later is a predetermined threshold value. It can be considered that it is “abrupt decline” when it changes so much that it exceeds. The above threshold value is, for example, 1.5 times the diameter of the wire electrode as the difference between the winding diameters, considering that the winding diameter cannot exceed the diameter of the wire electrode in a short period of time before and after the calculation period. Is set to a value that is approximately doubled. When this determination is made, the empty discriminator 88 inputs a bobbin empty signal S7 indicating that the wire bobbin 31 is empty to the motor controller 89. Upon receiving the bobbin empty signal S7, the motor control device 89 sends a control signal S10 instructing the servo motor 21 to stop driving, and stops the rotation of the servo motor 21, that is, the rotation of the drive roller 22.

  The wire tension and the wire speed (substantially feed speed) shown in FIG. 6 indicate changes when the rotation of the drive roller 22 is continued even after the wire bobbin 31 becomes empty as described above. In such a case, the time for the end of the wire electrode 2 away from the wire bobbin 31 to reach between the drive roller 22 and the pinch roller 23 is T2, and the end of the wire electrode 2 is the drive roller 22 and the pinch roller 24 (see FIG. 1). ) Is defined as T3. As shown in the figure, the wire tension greatly decreases when the end of the wire electrode 2 passes between the drive roller 22 and the pinch roller 23, and further when the end passes between the drive roller 22 and the pinch roller 24. Furthermore, it is greatly reduced. On the other hand, when the end of the wire electrode 2 passes between the drive roller 22 and the pinch roller 23, the wire speed is greatly increased due to the absence of pinching by these rollers (actually, the drive roller tries to increase to a predetermined wire tension). 22), and when the end passes between the drive roller 22 and the pinch roller 24, the feed force is lost and the feed force is greatly reduced to zero (actually, the wire tension causes the wire breakage). The drive roller 22 has stopped controlling because it falls below the threshold value to be detected).

  In order to reach between the driving roller 22 and the pinch roller 23 after the end of the wire electrode 2 is separated from the wire bobbin 31, the wire electrode 2 is supplied at a feed speed set in general wire electric discharge machining. Sometimes it takes at least about 5 seconds. On the other hand, the time required until the rotation of the servo motor 21 is stopped by the control signal S10 output from the motor control device 89 after the empty discriminator 88 determines the empty state of the wire bobbin 31 is clearly more than about 5 seconds. short. Therefore, when the rotation of the servo motor 21 is stopped as described above, the portion before the end of the wire electrode 2 is sandwiched between the drive roller 22 and the pinch roller 23, and the end is processed by the workpiece. It can prevent entering the gap. Therefore, it is possible to prevent the processed surface of the workpiece from being damaged by the end of the wire electrode 2. Further, since the wire bobbin 31 is replaced with a new one after being empty, it is possible to prevent the wire electrode 2 from remaining on the wire bobbin 31 and wasting the wire electrode 2.

  The empty discriminator 88 in the embodiment described above detects a sudden change in the rotational speed of the wire bobbin 31 from a sudden change in the winding diameter of the wire electrode 2 calculated by the winding diameter calculator 81. However, the present invention is not limited thereto, and the sky discriminator 88 may be configured to detect a sudden change in the rotation speed of the wire bobbin 31 by directly using the rotation speed signal S2 output from the rotation speed calculator 80.

  In such a case, if the rotational speed signal S2 indicates the rotational speed of the wire bobbin 31 by distinguishing the rotational direction, the absolute value of the rotational speed is compared with the threshold value as described above, for example. What is necessary is just to detect a sudden change of. Further, when the rotation speed signal S2 indicates the rotation speed of the wire bobbin 31 by distinguishing the rotation direction, it may be detected that the rotation direction is reversed as a rapid change in the rotation speed.

  Further, even when a sudden change in the rotational speed of the wire bobbin 31 is detected by directly using the rotational speed signal S2 output from the rotational speed calculator 80, the rotational speed signal S2 has only the magnitude of the rotational speed of the wire bobbin 31. (Ie, ignore the direction of rotation). In this case as well, as in the case of using a rapid change in the winding diameter of the wire electrode 2, a positive threshold value is set for the positive rotation speed, and it is detected that the rotation speed exceeds the threshold value. Thus, a sudden change in the rotation speed of the wire bobbin 31 can be detected.

  The present invention is not limited to the configuration of the embodiment shown in the drawings, and various modifications and applications are possible without departing from the technical idea of the present invention.

2 Wire electrode 20 Sending roller 22 Driving roller 23, 24 Pinch roller 31 Wire bobbin 38 Proximity sensor 40 Brake motor 80 Rotational speed calculator 81 Reel diameter calculator 82 Wire calculator (wire remaining amount detector)
83 display device 84 speed detector (wire speed detecting means)
85 Input unit 86 Storage unit 87 Length measuring device 88 Empty discriminator 89 Motor control device

Claims (2)

A wire wound around the wire bobbin in a wire electric discharge machining apparatus comprising: a wire bobbin for winding and holding a wire electrode; and a wire feeding means for pulling out the wire electrode from the wire bobbin and continuously feeding the wire bobbin toward a workpiece. A wire remaining amount detecting device for detecting the remaining amount of an electrode,
Rotation speed detection means for detecting the rotation speed of the wire bobbin;
A winding diameter calculation unit that calculates the winding diameter of the wire electrode in the wire bobbin based on the rotation speed of the wire bobbin detected by the rotation speed detection means and the feed speed of the wire electrode by the wire delivery means;
The relationship between the winding diameter and the remaining amount obtained based on the result of actual measurement of the winding diameter and the remaining amount of the wire electrode in the wire bobbin is stored in association with the specifications related to the winding diameter of the wire bobbin and the wire electrode. A storage unit;
An input unit for inputting the specifications of the wire bobbin and the wire electrode used in the electric discharge machining;
Using the relationship stored in the storage unit in association with the specification input to the input unit, the winding diameter calculated by the winding diameter calculation unit is applied to the wire winding diameter constituting the relationship. A wire remaining amount detection unit for determining the remaining amount of the wire electrode;
Wire remaining amount detection apparatus comprising: Wire speed detection means for detecting the feed speed of the wire electrode by the wire delivery means is further provided,
The winding diameter calculation unit uses the feed speed detected by the wire speed detection means as the feed speed of the wire electrode.
The wire remaining amount detection apparatus according to claim 1.