DE2559039B2 - DEVICE FOR DETERMINING THE EFFECTIVE SERVICE LIFE OF A TOOL - Google Patents

Description

The invention relates to a device for determining the effective service life of a tool, with a transducer for generating an electrical signal according to the processing resistance of a workpiece, a signal processing device for processing the electrical Signal, a comparator for generating a pulse when the output signal of the .Signalververarbeitungeinrichtung deviates from a predetermined Be / .ugssignal, and a device for determining the useful service life of the tool as a function of the output signal of the comparator.

For example, when making a laminated printed substrate with a thin copper foil, numerous small holes are made with the aid of drills. Quality and accuracy of the surface of the laminated substrate after the drilling process, / .. B. surface roughness, as well as the adhesion of synthetic resin are strongly influenced by the effective service life, ie the degree of wear of the drill. In other words, as long as the drill bit is sharp and has excellent cutting ability, excellent quality can be expected from the hole produced. However, as soon as the drill shows a certain amount of wear, the bore surface becomes rough b / .w. coarse, so that synthetic resin adheres to this coarse or rough surface. To avoid this disadvantage, the number of operations to be carried out with a drill is often set to a predetermined value of, for. B. 3000 predecessor drilling limited; As soon as the predetermined number of operations is reached, the drill is replaced by a new one. However, the service life of the drills available in the hand is subject to great swan blades. For example, the service life of some drills is only sufficient for 500 holes, while other drills can produce 5000 or more holes. If the life of a drill is determined by the number of operations that can be carried out with it, there is a risk that unsatisfactory linear printing substrates or the like will be produced using worn or improperly working drills.

Another method of determining de The lorin de becomes the operational lifespan of a drilling egg in the case of swarf incurred as a basis iu this provision was used. Even with these

γ. ι rcn isl the lle / ieluing / wipe the life ^ ' η hrcrs and the I-orm of the chip flour decisive. ^{l 'tS} "normally lierdein such a provision? ^a' done h'sichibeobachtung, the Hrgebnis this n '^ iiiinuing or not lieweriung conclusive. Previously, ■ turned procedures / for monitoring the He- ^' ^ 'lifespan of drills are liJier not exactly, "" l they require cumbersome operations. ¹¹ A is the I) T-AS 19 57 OM 5 is a computing device

f'r / .eiigung one for the wear of an artillery ι '' of their characteristic signal is known, wherein the kccheneinrichtung is to be formed so that they ^L each time a signal for the Verschleißzu 'i'mi of the tube provides that in the ^{Gunman S} -nr can be included, so dall ilic at every school; Correction of the guideline values depending on wear and tear is carried out, 'In order to achieve tlics, a limit switch and a selector switch for the identification of wear and tear and on the output side a counter / ur summation of the products identified by the multiplier is connected to a multiplier. The control switch can be mechanically connected to the gun and the counter can also be designed as a permanent body, a permanent memory can be connected to the counter. Thus managed this well ·: th execution a multiplier / for application of / is powered by a limit switch from an I and / to another by a selector switch for the representation of the respective Munilionsarl.

So with this famous execution the (Jrad read wear and tear on a gun barrel, based can be determined on 'a predetermined coefficient, and / was also dependent on the type of wedge used ammunition to make a corresponding payroll correction / u can. In such a way However, 1-egg line correction is made regardless of the initial state of the gun b / .w. (ieschüt / rohres carried out, and you can then get a good hearing result Achieve when the gun barrel / u start is in good condition. However, if the gun barrel at the beginning is already in a bad condition, the measurements or the Heuerleit Corrections no longer lead also desired hearing result.

The object on which the invention is based is to provide an improved device for Determination of the effective service life of a tool of the type defined at the beginning / u create with the help of which the service life can be determined automatically and precisely.

Based on the device of the type defined at the outset, this object is achieved according to the invention solved in that the Besiimmimgseinrichlung a first counter / to count the pulses from the comparator, a second counter / to count a predetermined one Number of measurements of the machining resistance of the workpiece by the transmitter and one Execution / to compare the counts of the first and second counters / to determine the zero / bar Has the service life of the tool.

According to the present invention are for example weis- 200 holes carried out on a workpiece. Then a work piece is read, which is niatenally and this corresponds exactly to the Weikstiick, in one or more l'robchohrungen pierced, and the BoIu vv idcrsiand is eaten. If at These I eslboiirungen two or more Hrgomsv. are obtained, according to which the Bohrw idcrsland , • exceeds a predetermined well, the Bohl stopped legged to be able to change the tool or the hollow. Hs therefore becomes a bad condition of a tool due to the first I estbohi ung displayed.

In detail, the message can be a \ οι 'Cilh.il te Weiiei education crlahren. that the Mel.lum formula 'a work / eugki al! messer aulweisi, the uniform or integral on a Weiksiückuscli provided isl. which in vertical / iieinaiuler running Λ and i'-Richluiigen is displaceable. Of the Transmitter can continue to execute emc for the gradual delivery of one from the same factory like the workpiece-related l'ruflmgs with every measurement or determination of the useful life . of the tool aiii point.

Other advantageous opportunities for education and training ng the hearing results from the sayings 4 to h.

The following is a preferred definition ι the HiTiiiduug based on the drawings in more detail. Hs shows

I ig. I a supervision on em BoIu kralimeßgerai. the is mounted on the table of a numerically controlled messenger device.

H ig. 2 shows a section to show the Auihaiis of Bohl dynamometer according to H i g. 1.

H'ig. 3 and 4 schematic representations for !.! ■ Clarification of the working principle of the Bohl kral ι messcr according to I · 'i g. 2,

in H i g. ^r ) and b graphical representations of the waveforms of the by means of the drill force meter according to I ι g. 2 determined torque and thrust forces,

H i g. 7 is a block diagram of an execution area in FIG Hearing and

;, H "ig. 8 to 11 graphical representations of signal waveforms for explaining the operation of the device according to H i g. 7th

The device shown in the figures for evaluating or determining the useful or, κ, effective service life of a drill contains a Bohrkrafimesser, which serves as a detector for supplying an electrical signal, which the resistance indicates during a drilling process. The drill claw knife is used to generate an electrical signal with a voltage which is proportional to the torque or thrust exerted by the drill on the workpiece during the drilling process. The drill dynamometer is on table 2 of a numerically controlled drilling device I ( 1), mounted on which a workpiece shown as laminieries bednickf.-s (circuit) substrate is mounted "serves the same construction as the substrate 5. The feed device 7 comprises a pulse or stepping motor 8. A threaded spindle 4 driven by the latter and a slider 10 aiii which can be displaced by its rotation. When the motor 8 is switched on, the slider becomes IO shifted towards the body i, so that dci Pnillmg h with leather measurement of the Bohrw iderslands schr In some cases, a previous piece is pushed through ile K, μ per> while the Molo: K wiul,, in this case in Ibercinsiimmung in the program of the ",,," τ, μ hm Sleiiersvsiems. For example, "" in! The table 2 lings cine, N Vhsc II and one, ) axis 12 s, shifted that the drilling egg wvmiu in.

unlined substrate 3 made about 200 holes Has. broke into a position above the body 5 of the bolirkrait knife 4! will. Unier this Conditions then the drilling resistance is measured for the first time during the drilling process on the test piece 6, and After completion of this measurement, the pulse or stepper motor is controlled by the numerical control system switched on in order to move the test item 6 upwards by one step. In this state then becomes the / wide drilling resistance measurement carried out. These measurements are taken one after the other, and if four Drill resistance measurements have been carried out, the table 2 is moved to the drill in the Bring the next drilling position on the substrate 3, or the drill is, depending on the result of the measurement, through replaced a new drill.

The following are the construction details of the body 5 of the power meter 4 with reference to FIGS. 2 to 4 explained. According to FIG. 2, the body 5 consists of a cylindrical housing 21 which is closed at the bottom and which is given away with a shoulder 22 on its inner wall. The edge 23.Ί of a membrane 23 is attached to the shoulder 22 by means of screws 21a. The membrane 23 has a thick peripheral edge 23.-? and a thick central part 236, which are connected to one another by a thin sieve section 23c, which makes the membrane flexible in the vertical direction. The rigidly formed central part 23b is connected in its center with a gate 23c /.

Under the middle part 236 of the diaphragm 23 is a Flat-chimney-shaped support member 24 is arranged, and between the two parts is a thrust-measuring piezoelectric Element Pl inserted. The support member 24 is secured by a preload screw 25, which is passed through the bottom of the housing 21 is screwed through, pushed upwards. The test item 6 is through a Holder 26 held, the outer circumference of which is held by a cross-shaped spring 27. This feather supported on the in F i g. 3 the holder 26 over the housing 21. The open top of the Housing 21 is closed by a suitable cover 28.

On the underside of the holder, a projection 26.7 is provided which rotatably receives a projection 23c on the upper side of the central part 23 spring membrane 23. A dynamic piezoelectric element P2 is inserted between the two lugs 26, 7 and 23c. According to FIG. 3, the pre-pressure or the preload is set with the help of an adjusting screw 30 acting on the shoulder 23c serves to transmit thrust.

The drilling resistance at Bolux-n of the test specimen 6 is determined as follows with the aid of the drill force meter described above: The test specimen 6 is set to the position shown in FIG. 2 is attached to the holder 26, and a drill D is advanced in the downward direction as shown by arrow C while it is rotated in the manner indicated by arrow B. In FIG. When a drilling process is initiated in this way, a torque and a thrust are exerted on ilen test specimen 6.

The direction of the torque is also indicated by the arrow / J (Fig. 3). The piezoelectric DrchmomentmeßelemcMi / '2 is between the Ansät / 23c of the membrane 21 and the Ansät / 26, -i des Holder 26 clamped. As a result, the element P2 is acted upon by the test object 6 Torque corresponding Di tick verprcßi so that it generates a corresponding electrical signal. By using a test item 6 from the same Material like the workpiece can easily change the degree of wear and tear at any point in time. the remaining operating time of the drill is determined will. F i g. FIG. 5 illustrates an example of a waveform of an electrical signal including the Torque for the case that an ultra-hard drill with a diameter of 0.8 mm at a Speed of 80,000 rpm and a feed rate of 0.03 mm / revolution a hole by a laminated printed substrate 1. The is effective during the torque measurement Membrane 23 as a rigid body in the direction of rotation of the drill. The rotational movement of the holder 26 is through the cross-shaped spring allows.

The thrust acting on the test specimen 6 during the drilling process acts on the piezoelectric thrust measuring element Pl on the support member 24 via the holder 26, the steel ball 31 and the membrane 23 (see FIG. 4). In the process, the holder 26 is displaced downwards by the cross-shaped spring 27 so that it exerts a pressure corresponding to the thrust on the piezoelectric element P1, the membrane 23 being able to bend in the vertical direction due to its construction described. Here, the piezoelectric element P1 generates an electrical signal corresponding to the thrust acting on the test object 6. FIG. B illustrates an example of a thrust curve which was determined under the same conditions as the curve according to FIG. 5.

As mentioned, torque and thrust can easily be determined from the piezoelectric Elements P2 and PI supplied electrical signals can be determined while doing preload adjustments before the measurement without further ado by twisting the adjustment screw 30 and 25 can be made.

Since the Bohrkraftmesscr measuring the drilling resistance according to Fig. 1 is mounted on the movable table in the direction of the axes X and Y , the workpiece does not need to be detached from the table for each measurement or determination of the useful life of the drill, whereby the measuring process is simplified . As a result, exact bores can be guaranteed at all times, as is particularly desirable when processing laminated, printed substrates or formwork panels.

According to Fig. 7 are those of the piezoelectric! Elements Pl and P2 emitted signals individually or together as Ausgr.ngssignal the Bohrkraftmcs sers 40 is applied to an amplifier 41. It should be noted, however, that the Bohrkraflmesser 40 not on di construction described is limited. Since the output of the drill force meter 40 is low The hamlet has tension and contains complex components resulting from the drilling process shape of the signal after amplification of the output; signals in the amplifier 41 by a filter 42 shaped. I. the following description is used by the fiiezoelectr see element PI generated .Strust signal as the Signi required for determining the drilling resistance / After amplification, the thrust signal has a waveform according to I · 'i μ. H. and after shaping dun

the filter has the smoothed waveform shown in FIG. 9. In the case of Fig. 9, the filter has one Cut-off or cut-off frequency of 1000 Hz: when using a low-pass filter with a cut-off frequency however, from 100 Hz the further smoothed waveform shown in FIG. 10 is obtained. Of course the gain coefficient of the amplifier 41 and the cutoff frequency of the filter 42 can depending can be set to any value according to the conditions of use.

The output signal of the filter 42 is integrated by an integrator 43 and then applied to one input of a comparator 44. A reference voltage Eo is applied to the other input of the comparator 44, so that this comparator supplies an output signal to a counter 45 when the output signal E \ of the integrator is greater than the reference voltage Ea

Figures 11 and 12 illustrate the relationship between the thrust of a drill and the number of drilling operations. 11 shows the thrust curve during the first drilling process, in which the maximum thrust is a little more than 0.5 kg. In the 8000th bore, however, the thrust increases to about 1.2 kg according to FIG. 12; this means that the maximum thrust has increased to about double due to drill wear. These data were determined with a drill with a diameter of 0.8 mm, which was operated at a speed of 80,000 rpm at a feed rate of 0.03 mm / revolution. The level of the output voltage E / of the integrator 43 also varies depending on the magnitude of the thrust. Therefore, if the thrust z. B. according to FIG. 11 is small, the integrator output signal E _{1 is} also small, ie it is, for example, about 3.5V according to FIG. 13. With increasing thrust according to FIG. B. according to FIG. 14 about 8.5V. For this reason, by setting an appropriate reference voltage Eo, it is possible to obtain an output signal from the comparator 44 when the useful life of the drill is reached and the thrust has exceeded a predetermined value. Although not shown in the figures, appropriate means are provided for changing the reference voltage Eo depending on the respective types of the drill and the workpiece.

The counter 45 is a 4-bit counter prefixed to a content of 2, which is reset by a transmission output signal from a 4-bit counter 46 which counts a predetermined number of drilling resistance measurements as a function of the output signal of the drilling force meter 40. The purpose of using the combination of two counters 45 and 46 is to statistically process varying resistances during drilling operations in order to determine the end of the working life of the drill according to the ratio between the number of measurements N ₍ > and the number of Measurements N \ in the case of Eo <E . In the present example, in which the relationship E () <E appears more than twice when performing four measurements, the 4-bit counter 45, which is preset to 2, generates a carry output signal, which is used as the end-of-life signal

ίο the drill is used to make the numerical Control system a command signal to. Interrupt the drilling process and change the drill to enter. If no transmission signal is generated by the counter 45, the numerical

The control system transmits a command signal to continue the drilling process via a converter 47. If in the device according to FIG. 4 the results of the first two of four measurements correspond to the condition Eo <E, the counter 45 generates an over-

: ii carry signal before counter 46 sends a reset signal and thereby interrupts the drilling process. In this case, the entire system is returned to the state before the initiation of the measurement from the numerical control system a free signal to the

y, counters 45 and 46 are supplied when drilling is interrupted or the drill is replaced.

The drilling resistance is measured, for example, every 200th drilling process, and the drilling work is under the control of the

jo numerical control system continued until the end of the usable service life of the drill has been reached or the drilling process on a workpiece has been completed is.

While in the above-described Ausführe approximately form a drilling dynamometer for measuring the when Drilling generated resistance is used, any other measuring device can be used which is the change of a physical quantity such as the cutting temperature and the number of

^ o revolutions of the drive shaft due to wear of the drill as an electrical quantity. With the device according to the invention can also the useful service life of any other cutting tool, e.g. B. a drill head or

4i cutting steel. If the invention c Device combined with a workpiece feeding device and a tool changing device a fully automatic drilling machine can be created.

vi Of course, the workpiece is not on cir laminated printed substrate or a printed formwork panel. In any case, jedocr the test piece 6 consist of the same material as the workpiece, because the test piece for representation

Vi of the same resistance to workmanship as in the work piece is used.

3 BhHt /

Claims (5)

Patent claims: 1. Device for determining the effective service life of a tool, with a Transmitter for generating an electrical signal according to the processing country a workpiece, a signal processing , direction for processing the electrical signal, a comparator for generating a pulse, when the output signal of the signal processing means is from a predetermined reference signal deviates, and a device for determining the useful service life of the tool in Dependence on the output signal of the comparator, thereby g e k e η η ζ e i c h net that the Determination device a first counter (45) for counting the pulses from the comparator (44), a second counter (46) for counting a predetermined number of measurements of the machining resistance of the workpiece by the transducer and means for comparing the counts of the first and second counters (45, 46) to determine the useful service life of the tool. 2. Device according to claim!, Characterized in that that the transmitter has a tool power knife (l-'i G. 2, P I, P 2), which is provided unitarily or integrally on a workpiece table is, which in X-iind running perpendicular to each other V-directions is displaceable. 3. Apparatus according to claim 2, characterized in that the transmitter further comprises a Device (7, 8, 9, 10) for con gradual feed of one made of the same material as that Workpiece existing test piece (6) for each measurement or determination of the useful life of the tool. 4. Apparatus according to claim 1, characterized in that the transducer is a Werkz.eugkraftmesser with a housing (21) of a rigid central part having membrane (2Ϊ) which is arranged in the housing (21) in a horizontal position and with its IJmfangsrand on the housing ( 21), a test specimen holder (26) for holding a test specimen (6) close to the surface of the membrane, the holder being rotatable about the axis of the membrane (2.3) and movable in a vertical direction, one of the holder (26 ) downwardly protruding first approach (26; i) a from the membrane (2.3) upwardly protruding and the first approach (26ü) facing second approach (2Ie), a first piezoelectric inserted between the two approaches (26.Ί, 23c) Element (P2) for torque measurement and a second piezoelectric element (P 1) inserted between the housing (21) and the underside of the membrane (21). 5. Apparatus according to claim!, Characterized in that d: iü the signal processing device (I- ig. 7) an amplifier (41) for amplifying the, μ mi transducer (40) emitted electrical signal, a low-pass filter (42) for removing the I. I >> cli! re (| uen / component from the output signal of the amplifier, an integrator (41) for integrating the output signal of the low-pass filter (42) when carrying out a measurement and an I im η! llung for applying the output signal of the integral (4)) has aiulen comparator (44). b. Device according to claim I, characterized in that that (Jer first counter (45) is set or set so that it has a first carry signal;! l at a count corresponding to the total number of measurements generated during a measurement cycle, and is preset to a predetermined payment. that the second counter (46) has a second :, carry signal to reset the first counter (45) generated when the second counter (46) the total number counted from measurements of the machining resistance on the workpiece, and that the determining device means for supplying the first carry signal as a processing final command signal and a converter for converting or converting the first request signal for the purpose of generating a command signal for the Eorisetziing of the processing.