EP2228186A2 - Wire saw device - Google Patents

Abstract

The device has a cutting wire (140) guided over a wire guiding plate (110) and deflection rollers (120), and movable in a longitudinal direction using tensile strength. A sensor (135) is arranged in a periphery region (A) of the wire guiding plate or the deflection rollers. The sensor detects change of current position of a saw wire (140) with respect to a position given as an optimal position, which is transverse to a longitudinal axis of the saw wire. The sensor is formed as inductive-, magnetic- or optical sensor, and is formed as a proximity sensor with a pre-amplifier.

Description

The invention relates to a wire saw apparatus according to the preamble of claim 1. In particular, the invention relates to wire sawing apparatus, which in a first application for sawing or cutting a crystalline billet or ingot into several blocks or bricks or in a second application for sawing or Slicing blocks or bricks to serve in wafers. In the first application, this is also understood to mean a wire-saw apparatus which comprises a squaring of cylindrical monocrystalline material, such as e.g. B. silicon, in blocks or the multicrystalline silicon in the form of cuboid bars divided into blocks or bricks and is commonly referred to as Squarer.

The crystalline billets or ingots to be cut have previously been produced by a crystal growing process. In previous squaring processes, external saws with diamond-coated saw blades or band saws were used. In more modern methods, the squaring is done by dicing by means of a sawing wire through a corresponding wire-sawing device, to which a first application of the invention relates. The squaring turns one originally round monocrystalline ingot into one square block with rounded corners or a square, multicrystalline large ingot several blocks with square cross section. A second application relates to a wire sawing apparatus used to make wafers of both multicrystalline and monocrystalline material, particularly silicon. In the process, the blocks or bricks created during the squaren are sawn into disk-shaped wafers.

When sawing or cutting according to both applications, an exact guidance of the saw wire must be achieved and it must be avoided overuse of the material.

The sawing wire may be a high-tensile strength steel wire, which may additionally have embedded on its surface, for example in a nickel alloy, diamond grains. However, it may also be made of innumerable individual fibers existing plastic wire having on its surface abrasive grains (see, eg WO 2003/041899 ).

In the currently most commonly used sawing technology, the wire does not come into direct contact with the material (silicon). Because the sawing frames are sprayed with a mixture of glycol or oil and silicon carbide grains, which is commonly called "slurry". The silicon carbide acts as an abrasive medium, which causes the actual sawing of the material. Thus, in the narrow sense, it is not a sawing, but a Drahttrennläppen.

The invention is also to improve the wire guide in the known as Squarer wire saw devices that are used for sawing or Cutting a crystalline ingot into a plurality of blocks to form a preferably square wire array of preferably intersecting cutting wires or cutting wire sections. However, the invention is not intended to be limited to this type of wire-sawing apparatus. In these squarers, the cutting wire is passed over a plurality of wire guide discs and moved longitudinally under tension, each wire guide disc having a plurality of grooves for guiding the cutting wire. On the four sides of the square, a plurality of wire guide discs are rotatably mounted in an arrangement, which is also referred to as wire guide roller. The wire guide discs are mounted at defined intervals to achieve the desired cutting widths. These devices are particularly suitable for the production of blocks, from which in the subsequent manufacturing step "wafer sawing" typically 130μm to 200μm thick solar wafers are produced.

Another type of wire saw apparatus is for example from DE 100 03 240 A1 known. This wire saw device is a multi-wire saw and is used in particular for sawing a silicon ingot into a plurality of wafers or semiconductor wafers. For this purpose, the apparatus has a wire group in which a cutting wire is guided over a plurality of grooved rolls, the grooves being spaced apart from each other as required by the thickness of the desired wafers. Thus, these rollers act as multi-groove or grooved roller or cylindrical wire guide rollers. Accordingly, is from the DE 100 03 240 A1 a wire saw apparatus known in which the wire cutters are guided over roller-shaped wire guide rollers and longitudinally under tensile stress to be moved. This device, also referred to as a multi-wire saw, is used for the process of wafer sawing.

From the DE 10 2007 019 566 A1 It is known that the material of which the lining of the wire guide rollers consists, and the contour of the plurality of grooves of the wire guide rollers of this wire saw apparatus must be adjusted in order to minimize their wear. Thus, the service life of the wire guide rollers are increased, the wire optimally guided and quality characteristics of the wafers produced in this multi-wire saw, such. B. Bow and Warp, positively influenced.

From the EP 1 110 652 B1 is a wire saw device (multi-wire saw) known in which also cutting wires are guided over wire guide rollers. To ensure optimum wire tension during the sawing process, tension sensors are provided to measure or monitor the wire tension.

In addition to maintaining optimum wire tension, care must be taken in each type of wire sawing apparatus to ensure that the cutting wire remains in the respective groove on the wire guide roll (multi wire saw) or wire guide disk (squarer). In particular, it must be avoided that a so-called wire jump occurs from one groove to another. In the process of wafer sawing, however, each adjacent groove of the wire guide roller is already occupied by a wire running therein, whereby in this process a wire jump occurs less frequently, only leads to the failure of two adjacent wafer due to geometry tolerance exceeded and a wire jump is usually tolerated. Wire jumps in wafer sawing usually have their cause in the wear of the grooves, such as the EP 1 110 652 B1 describes.

All these types of wire saw devices have in common that they in addition to the aforementioned wire guide elements, so the wire guide rollers (Multi Wire saw) or joined together to wire guide rollers wire guide wheels (squarer) for determining the product geometry precision guidance of the engaged wire sections, also Also have other wire guide elements for the purpose of defining the wire path, which are referred to in more detail as wire guide discs, pulleys, guide rollers or Umlenkzylinderrollen.

Therefore, it is of general interest to limit the natural wear of the contact surfaces of wire guide elements, that is, the contact surfaces that directly contact the cutting wire, such as those shown in Figs. Do not allow all pulleys in the machine to wear too much so that the cutting wire runs along the predetermined paths.

Furthermore, it should be ensured that a wound on a supply roll and a transverse to the wire movement extending guide roller wire follows the windings of the supply roll or its transverse forces and thereby moves freely on an extended Umlenkzylinderrolle and does not get stuck on the ever-occurring wear grooves of Umlenkzylinderrolle.

In addition, it would be desirable to be able to determine the tension of the cutting wire at as many points between different wire guide elements.

• Sprünge des Drahtes aus der vorbestimmten Rille einer Drahtführungsscheibe heraus detektiert werden,
• der Verschleiß von Umlenkrollen eines jeden Typs detektiert wird,
• detektiert wird, wenn das freie Wandern des Drahtes auf den Umlenkzylinderrollen nicht mehr gegeben ist
• die Zugspannung des Schneidedrahtes nicht nur in der Nähe von Aufwickel- oder Abwickelspule bestimmt werden kann.

Accordingly, it is an object of the present invention to provide a wire saw device, in which the above-mentioned disadvantages and requirements are overcome or solved in an advantageous manner. In particular, should be achieved by the invention that

• Cracks of the wire are detected out of the predetermined groove of a wire guide disc,
• the wear of pulleys of each type is detected,
• is detected when the free migration of the wire on the Umlenkzylinderrollen is no longer given
• the tension of the cutting wire can not be determined only in the vicinity of take-up reel or take-up reel.

In particular, it should be reliably recognized in a wire-saw apparatus such as a squarer for squaring ingots when the saw wire jumps out of the predetermined groove of a wire guide disk.

It is also to be ensured in wire-saw devices of this or other type that the natural wear of the contact surfaces of wire guide elements can be detected early and automatically and prevented that the cutting wire does not leave the intended guideway and / or does not get caught in a developing wear groove.

The object is achieved by a wire saw device with the features of claim 1.

Accordingly, it is proposed that the wire-saw device has at least one sensor which is arranged in a surrounding area of at least one of the wire guide elements and which detects a change in the current position of the cutting wire relative to a predetermined position as an optimal position transverse to the longitudinal axis of the cutting wire.

The wire sawing apparatus according to the present invention therefore comprises at least one sensor arrangement which serves to monitor the position of the guided wire in the vicinity of wire guide elements and thus in particular to monitor the wire guide in the device and / or the state of wear of the wire guide elements and / or the wire tension ,

As wire guide elements, any type of wire-guiding elements are considered, in particular considered wire guide wheels, pulleys, guide rollers or Umlenkzylinderrollen. The respective sensor can be a spatially resolving sensor or detector, that is to say be such that it detects a spatially resolved change in the current position of the cutting wire. A spatially resolved change in the position of the cutting wire in the vicinity of a wire guide disc provides the indication of a wire jump in one of the adjacent grooves, or provides the indication of an unacceptable wear of the guide roller or on an unacceptable wear of a Umlenkzylinderrolle or on an associated state change of the cutting wire. Also, the respective sensor may be a time-resolved sensor or detector, that is to be so designed to detect a time-resolved change in the current position of the cutting wire to detect an associated state change of the cutting wire, in particular wear and / or change in tensile stress.

The wire saw device can be designed for example as a multi-wire saw, the block-like body of crystalline material, in particular ingots of silicon, divided into several slices or wafers, in particular by Drahttrennläppen or wire cutting loops cuts.

Also, the wire saw device may be formed, for example, as a squarer, the block-like body of crystalline material, in particular ingots of silicon, divided into several blocks or bricks, in particular cut by Drahttrennläppen. In this case, at least one sensor is arranged in each case in the surrounding area of one or more wire guide disks (n) so that the sensor detects whether the cutting wire remains in the groove in which the cutting wire is guided or has jumped into another groove.

Typically, each of the four sides of the wire saw apparatus, referred to as a squarer, is an assembly of a plurality of such wire guide disks. This arrangement may also be referred to as wire guide roller or composite wire guide wheels. Preferably, the sensors are located in a surrounding area that supports the reeling and / or Abrollbereich for the cutting wire on or from the respective wire guide disk. In particular, the respective sensor comprises exactly one groove of the respective wire guide disk.

Here, a sensor device is proposed that has at least one such sensor and can be mounted on a wire-saw device.

Thus, the wire saw apparatus presented here is preferably provided with a plurality of sensors, which are aligned with the guided in the grooves cutting wires out and recognize any occurring wire jump safely and immediately. Since the sensors are always aligned to a predetermined groove, operator errors are avoided when setting up the wire field, since the misplaced wire must be detected in the predetermined groove.

In the case of a detection of a change in position, which indicates an unacceptable state change, such as a wire jump, the cutting or sawing process can be stopped. By eliminating the wire jump by manual intervention then there is the possibility to prevent that in the case of continued squaring of an ingot without manual intervention in the worst case up to 8 blocks because of geometry errors to reject, for example, from a ingot with a base of 700mm x 700mm, which should be sawed into 16 blocks measuring 156mm x 156mm. In addition to the detection is to avoid rejects in particular necessary that a wire jump can be detected immediately and the machine can be brought to a standstill.

At least one sensor is preferably arranged in the surrounding region of each wire guide disk such that the sensor detects whether the respective cutting wire remains in the groove in which the cutting wire is guided. The sensors are preferably mounted on the frame, which also carries the wire guide roller with the respective wire guide discs, or on a holder attached thereto. As sensors, for example, inductive, magnetic and / or optical sensors can be used. It is also advantageous if the respective sensor is designed as a proximity sensor, i. as a sensor that can detect metal objects without physical contact. For this purpose, different sensor types, such as an electromagnetic induction high frequency oscillation type, a magnet type sensor type, or a capacitive type sensor.

Preferably, the wire sawing apparatus includes control circuitry coupled to the sensors which processes a sensor signal from the sensor and which controls stopping of the longitudinally moving cutting wires if at least one of the sensors indicates the occurrence of a wire jump. Preferably, the control circuit may also be integrated in a motor controller for at least one electric motor drive for moving the cutting wires. The drive preferably contains several motors.

The control circuit is preferably designed such that it has at least one comparator which transmits the sensor signal compares to a predefinable threshold. Also, the control circuit may comprise at least a first circuit stage, which checks whether a ground fault of the cutting wire is present. Because in a cost-effective variant, the sensor is in a metal housing, which in turn is conductively connected to the device. Thus, any possibly occurring contact of the sensor can be detected by the cutting wire and protective measures can be triggered. In addition, the control circuit may additionally have at least one second circuit stage, which continuously checks the function of the respective sensor. Preferably, a sensor with (in the sensor housing or in the cable) integrated amplifier is used, so that the sensor function or the wiring between the sensor and the amplifier can be tested via a separate output. Likewise, the control circuit may comprise at least one linking stage, which links a plurality of sensor signals together. This may be, for example, a logical OR circuit.

Figur 1 a) und b)

zeigen in einer Frontansicht bzw. in einer Seitenansicht b) schematische Darstellungen einer Drahtsäge-Vorrichtung nach einem ersten Ausführungsbeispiel in Form eines Squarers, wobei exemplarisch anhand von zwei Drahtführungsscheiben die Anordnung der Scheiben sowie des Sensors und die Führung des Drahtes dargestellt sind.

Figur 2

zeigt schematisch in einer dreidimensionalen Ansicht den Aufbau der Drahtsäge-Vorrichtung nach dem ersten Ausführungsbeispiel.

Figur 3

zeigt zu den Fig. 1 und 2 im Detail einen Ausschnitt einer mit mehreren Rillen versehenen Drahtführungsscheibe, sowie den nahe dazu angeordneten Sensor zur Detektion von Drahtsprüngen

Figur 4

zeigt in einer ersten Ausführungsform eine erfindungsgemäße Steuerschaltung für die in Fig. 1 bis 3 dargestellten Sensoren.

Figur 5

zeigt eine Variante der erfindungsgemäßen Steuerschaltung für die in Fig. 1 bis 3 dargestellten Sensoren.

Figur 6 a)

zeigt in schematischer Darstellung einen anderen Teilbereich einer Drahtsäge-Vorrichtung(vorkommend sowohl in einem Squarer als auch einer Multi Wire Säge) und repräsentiert einem zweiten Anwendungsfall, wobei ein Sensor die Position des Schneidedrahtes bei seiner Auf- oder Abwicklung detektiert.

Figur 6 b)

den Teilbereich der Drahtsäge-Vorrichtung nach Fig. 6b) zeigt, wobei die Auf- oder Abwicklung des Schneidedrahtes weiter fortgeschritten ist.

Figur 7

den Teilbereich der Drahtsäge-Vorrichtung nach Fig. 6a) und 6b) zeigt, wobei eine durch Verschleiß an einer Umlenkzylinderrolle hervorgerufene fehlerhafte Drahtführung bzw. Drahtwanderung erkannt wird.

Figur 8

zeigt in schematischer Darstellung einen Teilbereich einer Drahtsäge-Vorrichtung nach einem dritten Anwendungsfall, wobei ein Sensor die Position des Schneidedrahtes an einer Umlenkrolle detektiert, um den mechanischen Verschleiß der Umlenkrolle zu überwachen.

The invention and the resulting advantages will be described below in more detail and by means of embodiments, reference being made to the accompanying drawings

FIG. 1 a) and b)

show in a front view and in a side view b) are schematic representations of a wire saw apparatus according to a first embodiment in the form of a squarer, wherein the arrangement of the discs and the sensor and the guide of the wire are shown by way of example with reference to two wire guide discs.

FIG. 2

shows schematically in a three-dimensional view of the structure of the wire saw apparatus according to the first embodiment.

FIG. 3

shows to the Fig. 1 and 2 in detail a section of a multi-grooved wire guide disc, as well as the arranged close thereto sensor for detecting wire jumps

FIG. 4

shows in a first embodiment, a control circuit according to the invention for the in Fig. 1 to 3 illustrated sensors.

FIG. 5

shows a variant of the control circuit according to the invention for in Fig. 1 to 3 illustrated sensors.

FIG. 6 a)

shows a schematic representation of another portion of a wire saw apparatus (occurring in both a squarer and a multi-wire saw) and represents a second application, wherein a sensor detects the position of the cutting wire in its winding or unwinding.

FIG. 6 b)

the portion of the wire saw device after Fig. 6b ), wherein the winding or unwinding of the cutting wire has progressed further.

FIG. 7

the portion of the wire saw device after Fig. 6a) and 6b ), wherein one by wear on a Umlenkzylinderrolle caused faulty wire guide or wire migration is detected.

FIG. 8

shows a schematic representation of a portion of a wire saw apparatus according to a third application, wherein a sensor detects the position of the cutting wire on a pulley to monitor the mechanical wear of the pulley.

The embodiments described below illustrate the versatile application of the invention. The subject matter defined by the term "wire sawing apparatus" is to be understood very generally and includes all apparatuses for breaking up crystalline material, such as wire saws for cutting blocks, bricks or columns in wafers, squarers for breaking up crystalline ingots into so-called blocks, bricks or pillars etc. "Sawing" is understood here to mean any kind of dicing of material by means of one or more cutting wires, in particular also so-called wire-separating lapping, in which the wire itself does not cut the material, but essentially one at or the contact point ( n) between the material and wire introduced mixture of glycol or oil and with abrasive grains (so-called slurry). The wire moves the slurry on or in the contact zones, so that the material is removed by means of wire cutting laps. For guiding the at least one cutting wire wire guide elements are used, which may have different configurations, such as wire guide disks, guide rollers or Umlenkzylinderrollen, Guide rollers, driven or non-driven guide rollers etc. ,

On the wire-sawing apparatus, instead of dividing crystalline ingots into so-called blocks, bricks or columns, etc. by wire-cutting lapping, the process of wire-cutting can also be used. In wire cutting, a wire is used in which the abrasive particles (e.g., diamond particles) are metallically bonded to the surface of the wire.

The FIGS. 1 to 5 refer to application examples, which relate to the wire guide in the wire field of a squarer, wherein the sensors are arranged in the vicinity of the wire field, in particular to avoid the occurrence of wire jumps on wire guide disks. The FIGS. 6 . 7 and 8th describe further applications of the sensor arrangement, in which in particular an unobstructed migration of the wire to Umlenkzylinderrolle should be ensured or the wear of wire guide wheels to be monitored. The sensor arrangement for detecting the position of a sawing wire is therefore not limited to the detection of a wire jump on wire guide disks or the wear of wire guide disks. This sensor arrangement can be used on all types of wire-saw devices, such as square or multi-wire saws. The sensor is always arranged in the vicinity of a wire guide disk or an analogous position in the vicinity of a deflection roller, a guide roller or a deflection roller or the like, and detects the deviation of the actual position of the wire from its desired position. These numerous applications are described below with reference to the FIGS. 1 to 8 described in detail.

As a first exemplary embodiment is here first on the basis of FIGS. 1 to 3 a wire saw device in the form of a Squarers described on which a sensor according to the invention is mounted. The sensor is connected to a control circuit based on the Fig. 4 and 5 in two embodiments will be described.

The FIGS. 1a) and 1b 2 and 2 show in different views a wire saw apparatus according to the invention in the form of a squarer 100 which cuts into blocks or bricks by means of a cutting wire 140, a monocrystalline ingot 200 or multicrystalline ingots 200 of a crystalline material such as silicon.

The the FIG. 1 shows on the basis of the views a) and b) by way of example the guidance of the cutting wire 140 via wire guide elements in the form of pulleys 120 and wire guide disks 110 and the arrangement of at least one sensor 135 for detecting the current wire position and reliable detection of a wire jump. Before this will be discussed in more detail, should first be based on the FIG. 2 the general structure of the Squarers are described.

The FIG. 2 shows in a three-dimensional view of the squarer 100 having a frame or a holder 130 for a plurality of wire guide elements in the form of wire guide disks 110 and pulleys 120 (all a kind of previously enumerated wire guide elements). The over the Wire guide-guided cutting wire 140 intersects in the cutting area and tensions there a wire field 145, which is suitable for sawing multi or monocrystalline blocks or ingots. The cutting wire 140 is guided over the guide rollers 120, which are located in the upper region of the holder 130, to the respective wire guide disks 110, which are located in the lower region of the holder 130 and for the deflection of the cutting wire in the horizontal cutting direction and for an exact wire guide to care.

In the vicinity of each wire guide disk 110, a sensor 135 is provided, which is aligned with the guide or the current position of the cutting wire in order to recognize any occurring wire jumps immediately. Because the machining process determines in which groove the cutting wire should be located. Should the cutting wire, for whatever reason, leave this groove or optimal position, this is immediately recognized and displayed or evaluated by the invention proposed here.

The sawing or cutting wire 140 used here is only slightly thicker than a human hair with approximately 250 μm. Slicing an ingot 200 (see also Fig. 1 ) with a wafer-thin brass-coated steel wire usually takes 5 to 7 hours. The wire makes a pendulum motion by moving the wire back and forth through the material at a speed of up to 15 m / s. The illustrated roller system ensures that the saw wire passes through all the sawing channels one after the other. For cutting the ingot 200 into, for example, sixteen blocks, a wire roll with about 400 km of wire is needed.

The wire guide will now be based on the FIG. 1 described in more detail:

The FIG. 1 shows on the basis of the views a) and b) by way of example the guidance of a cutting wire 140 on the pulleys 120 and wire guide disks 110 and the arrangement of the sensor 135 for the reliable detection of a wire jump. The guided over the rollers wire 140 is brought by the wire guide discs 110 in the horizontal cutting position and thus accurately positioned for sawing the ingot 200. The respective wire guide disks 110 have for this purpose a plurality of grooves (see also FIG. 3 ). A mounted on the holder 130 each in the immediate vicinity of the wire guide disk 110 sensor 135 checks the exact position of the cutting wire 140 and reports any occurring wire jump. The environment A detected by the sensor corresponds to a narrower area near the grooves of the wire guide disk 110. The sensor 135 shown here is configured as a proximity encoder in the form of a high frequency oscillation type comprising a measuring coil, a vibration circuit, an amplitude detection circuit, and an output circuit. All circuit elements can be integrated in one housing. Alternatively, the measuring coil may be incorporated in a separate measuring head and connected by a cable to the vibration circuit mounted with the remaining circuit elements in another housing. In between there is a cable (coaxial cable) in which an amplifier can be integrated if it has a certain length. By means of the oscillation circuit and the measuring coil, a high frequency magnetic field is generated, which in the nearby metal object (here in the cutting wire) a Induced current (eddy current) generated. The smaller the distance between the sensor and the metal object, the larger the induction current and the larger the load in the oscillation circuit. These changes are detected in the sensor by the amplitude detection circuit located therein and via the output circuit as a measurement signal or sensor signal (see signal S Fig. 1 ).

Various embodiments of the proximity sensor are conceivable, such as e.g. as a switching sensor with internal or external electronics or amplifier, or e.g. preferred as a switching sensor with external adjustable amplifier. Thus, in the sensor itself is preferably always a part of the electronics or even the entire electronics. The non-sensor electronics or amplifier may be e.g. be in the cable, in a connector or be designed as a separate amplifier.

The FIG. 3 shows in detail the upper portion of the wire guide disk 110 with the grooves provided therein. Here, for example, 10 equidistant grooves are present, of which the grooves R1, R5 and R10 are provided here by way of example with a reference numeral. The middle groove R5 is intended to define the current and desired ideal position or desired position P0 of the cutting wire 140. The sensor 135 mounted in the immediate vicinity, which represents, for example, a proximity switch with integrated amplifier, detects the current and optimum position of the cutting wire. As soon as a wire jump from the current groove R5 should occur in another groove, this is immediately detected by the sensor 135. The sensor is with one later described circuit which performs an evaluation of the sensor signal and at a wire jump, the drive means (not shown) of the wire sawing device stops.

The FIGS. 4 and 5 show in further details examples of the structure of the sensor device according to the invention with associated control circuit.

In the FIG. 4 For example, a first control circuit 150 connected to the sensor 135 is shown. The sensor supplies a sensor signal S, which is present at the input of the control circuit 150. The control circuit 150 has, in particular, a comparator or differential amplifier 151 which, on the basis of a threshold value detection, detects whether the sensor signal S indicates a wire jump or not. The differential amplifier 151 is followed by a trigger stage 152, which forms a rectangular trigger signal and this leads to a link stage 153. The connection stage, which is designed here as a logical OR gate, combines a plurality of sensor signals and thus causes a control signal ST to be generated at the output of the control circuit as soon as at least one of the sensors detects a wire jump. The combination stage 153 is followed by an output pulse shaping circuit which generates a floating control signal ST, which is fed, for example, to the actual drive control (machine control) for electric motors which drive the wire saw apparatus.

The control circuit 150 may additionally be provided with a first switching stage 155 which checks whether a short to ground of the respective wire is present. Thus, an additional safety function is installed. In addition, the circuit may also additionally have a second circuit stage 156, which causes an automatic safety / function control of the sensor.

The sensor signals processed by the circuit 150 can not only be detected by the wire-jump sensors, such as those shown in FIG. The sensor 135, but also come from other sensors that measure or detect, for example, the wire tension. Thus, in the control circuit 150 different sensor signals can be merged and processed. The drive of the wire saw device is stopped, for example, even if the wire tension should be outside a predetermined tolerance range.

The FIG. 5 shows another embodiment of the control circuit 160, which corresponds to a simplified embodiment of the circuit 150 described above. The signal S coming from the sensor 135 'is fed to a differential amplifier 161, which also acts as a comparator here. Differential amplifier 161 provides signal preprocessing by converting the analog sensor signal to a switching level with a defined voltage swing of, for example, 0 or 15 volts. A downstream trigger stage 162 is used for pulse formation and for additional security, the standardized edge slopes are generated for the subsequent stage. For this example, a monoflop can be used. In the example shown then follows a link stage 163, which is also designed as OR gate and a plurality of sensor signals or signals from a plurality of sensors 135 'and 136' merges. Thereafter, the output pulse shaping follows in a corresponding stage 164, so that finally a control signal ST 'is produced which effects the stopping function in the machine control. The control circuit 150 or 160 according to the invention can also be integrated into the machine control.

The here on the basis of FIGS. 1 to 5 previously described embodiments of the invention are particularly suitable for reliably detecting a change in the current position of the cutting wire on the respective wire guide element (wire guide disk, deflection roller, guide roller, deflection roller, etc.). By means of a control circuit or evaluation electronics realized therein, in the case of a wire jump, a control signal or a switch-off pulse for the drive of the wire saw device is generated. In the case of other types of position changes of the cutting wire, such. In Fig. 6 . Fig. 7 and Figure 8 shown, the control signal does not necessarily lead to a shutdown of the drive but can lead to a message at the end of the ongoing sawing process to check the monitored element and replace if necessary.

The invention has, inter alia, the advantage that a wire jump is detected reliably and immediately and thus the machine or the drive is stopped immediately. In addition, eliminates the need to re-set the wire field an additional Check the position of each wire in the designated groove.

The control circuit according to the invention is characterized in particular by the fact that it outputs a set pulse for a memory cell D-flip-flop after a triggering of any input edge at the sensor output. It is therefore a switching sensor equipped with a D-latch. Thus, in the event of an event, which may also be very short, signaling (e.g., visual alarm indication) is set and it is avoided that events are not recognized by operating personnel (absence, too short a temporary event, etc.). The triggering serves in particular to increase immunity to interference and variability. For the electronics, preferably half of the sensor supply voltage can be used. This contributes to a sufficient noise immunity. For the logical combination of a plurality of sensor input signals can be resorted to a conventional logic circuit, preferably with particularly low-loss components are used. As a sensor type, for example, a DC proximity switch with amplifier is suitable.

The above based on the FIGS. 1 to 5 described embodiments relate to an inventively designed wire saw apparatus in the form of a Squarers having a guided over wire guide disks and under tension longitudinally moving cutting wire, each wire guide disk has a plurality of grooves for guiding the cutting wire. It will be understood that the invention also applies to any other type of wire sawing apparatus can be, in which at least one cutting wire is guided in a groove, wherein it is irrelevant whether the leadership is done by means of a wire guide disc in the strict sense. Therefore, the term "wire guide disk" should not be understood to be narrow, but include any type of wire guide elements that may be provided with grooves, such as rollers, wheels, rollers, cylinders and the like.

Based on Figure 6a), 6b ) and 7 A further exemplary embodiment of the invention will now be described, namely a sensor system for monitoring a wire guide not impaired by roller wear during a winding or unwinding operation:

The FIG. 6a ) shows a portion of a device according to the invention, in which the cutting wire 140 is guided over several wire guide elements in the form of various guide rollers 121 and 122 (also called guide roller) and an extended Umlenkzylinderrolle 124 on a wire supply spool 125 to be wound up there. As a counterpart to the wire supply spool 125 shown, a further wire supply spool (not shown) is provided from which the cutting wire 140 is unwound, passed through the material in the direction of pull Z, and then, as in FIG FIG. 6 a) represented, is guided over the guide roller 121 and guide roller 122 and the Umlenkzylinderrolle 124 on the wire supply spool 125 and wound there.

The successive winding and rewinding of the wire is an essential feature of a wire saw machine, since it is advantageous to move the wire in the so-called pendulum cut. In this case, a certain length of wire is unwound from the unused wire spool and wound after passing through the object to be sawed on a collecting coil for used wire, the wire movement then brought to a standstill and then by means of a backward movement of the wire a slightly shorter length wire from the The old wire spool was taken and wound back onto the supply reel. And so on. Typical lengths are 300 m in the forward direction and 280 m in the backward direction. The winding of the used wire is done with a pitch of a few mm per coil revolution with a used coil length of 100 mm to 200 mm.

The cutting wire 140 must be wound onto the wire supply spool 125 as uniformly as possible. For this purpose, the guide roller 122 is vertically moved up and down, wherein the cutting wire 140 slides over the Umlenkzylinderrolle 124 or wanders. This Umlenkzylinderrolle 124 has an elongated, roller-like shape and consists of a plastic, preferably a material of low density, high wear resistance and the greatest possible static friction against the wire.

The FIG. 6a ) shows the cutting wire 140 in the upper position, ie at the upper end of the Umlenkzylinderrolle 124, and the FIG. 6b As can be seen, the vertical position of the cutting wire 140 on the Umlenkzylinderrolle 124 changes accordingly. Because of the deflection angle of the wire to the guide roller 121 and the As a result, the downward thrust force on the wire results in the wire trajectory of the downward movement of the roller 122 being voluntary. This voluntary consequences is only hindered if circumferential grooves caused by wear are on the reversing cylinder roller 124. By means of a sensor 135, which is rigidly connected to the guide roller 122, the position of the cutting wire 140 is monitored to this guide roller 122. If no wear on the rollers 122 or 124 occurs or makes itself felt, this position remains unchanged and is always on the upper rolling plane of the guide roller 122nd

The FIG. 7 shows the situation in which disturbing grooves have formed on the Umlenkzylinderrolle 124 due to material wear, of which at least one wear groove V is formed so deep that the cutting wire 140 gets stuck in this wear groove V in its downward movement (hiking). In such a case, the cutting wire 140 will no longer be uniformly wound up on the wire supply spool. By the sensor 135, however, this case is detected immediately, since the actual position P # of the cutting wire 140 briefly deviates upwards or downwards from the nominal position P0 specified relative to the guide roller 122 (depending on the winding or unwinding direction) and the Sensor 135 detects this. In this case, as shown in Figure 6c, the cutting wire 140 either lifts off from the guide roller 122 and increases the distance between the cutting wire 140 and the upper running plane of the guide roller 122 (in the case illustrated here, there is no wire deflection on the guide roller 122 ) or the cutting wire is deflected much more than intended on the guide roller 122 (not shown case).

The sensor 135 is, for example, an inductive proximity sensor with integrated preamplifier, which recognizes this change in position immediately and to the control circuit (s. Fig. 4 or 5 ), which can turn off the device or machine immediately. The sensor 135 thus monitors the optimum position during the downward movement of the cutting wire 140.

Suitable sensors for the detection of analog signals are both inductive sensors without external power supply and sensors with external power supply. The former sensors generate signal amplitudes of only a few 100 mV. To increase the immunity to interference, i. Increasing the signal-to-noise ratio, the signal should be amplified. Suitable enhancers are e.g. Differential amplifier, electrometer amplifier, instrumentation amplifier. The use of a bandpass with simultaneous signal amplification is advantageous.

Sensors with external power supply and integrated signal amplification have signal amplitudes of several volts. This means higher interference immunity. The filtering of the signals takes place as described above. For the evaluation of fast signal changes z. B. sensors with a signal processing frequency of several KHz used.

The in the FIGS. 6a), 6b ) and 7 shown arrangement can thus achieve a reliable monitoring of the wear on the Umlenkzylinderrolle 124.

In the Fig. 6a), 6b ) and 7 arrangement shown also allows to monitor the wear of the guide roller 122, since in the case of wear this, the cutting wire 140 cuts deeper into the roll and the actual position P # of the separating wire is thus permanently lower than that in contrast to the previously described case Target position P0.

In order to detect the role wear on the other rollers, such as the pulleys 120, 121 or 121 *, the arrangement can FIG. 8 be used.

For this purpose, a sensor 135 *, which detects the position of the cutting wire 140, is mounted in the vicinity of the deflection roller 121 *. If wear occurs on the roller 121 * over time, this manifests itself in particular in the fact that the cutting wire 140 eats into the roll material. This occurs especially in roles that have a high slip with the wire, such as drive rollers or braking rollers. The abrasion of the material and the burying of the wire 140 reduce the effective diameter of the roller 121 *. The wire 140 is then in a position that is significantly lower than the normal position and in particular becomes critical when two along the wire path successive pulleys are not in a plane but their axes are inclined against each other to give the wire path so complex contours. The service life of a deflection roller is between 10 and 50 hours, depending on the specific process parameters. Is in the currently visually and manually running wear control of the critical wear of a Override pulley, this can lead to the jump off the wire from the roll during the cut and in the further to the crack of the wire.

By the sensor 135 * a position change of the wire 140 is detected in this case as well. Both in the example shown here Fig. 8 as well as in the example Fig. 7 the position of the wire changes transversely to its longitudinal axis. The position of the wire in the longitudinal direction changes in the present examples ( Fig. 6 to 8 ), since one can assume an invariance of the geometric relations with respect to the natural movement of the wire along its axis.

With the aid of the described invention, the wire tension of the cutting wire can also be detected and / or monitored. For this purpose, in each case a sensor is mounted in the immediate vicinity of the wire 140 at one or more locations, which is preferably designed as an inductive sensor, which can measure minimum transverse vibrations of the wire, if the wire to vibration (mechanical and / or electromagnetic) is excited.

For example, an electromagnetic excitation may be effected by exciting a repetitive pulse repeating in a certain time interval or by a "tunable" sinusoidal frequency (wobbling).

The current tension of the wire can then be given the given parameters wire diameter, wire density and unsupported length between two deflection or guide points determine. This is particularly important for wire sections between the exit from the sawed object and the wire guide roller following wire movement, because at this point the actual tension of the wire is very undefined, because of not exactly predictable frictional force of the wire in the sawn object on the one hand and not exactly predictable Zugspanungsübertragung by the wire guide roller on the other hand.

The optimum tensile stress then corresponds to a certain vibration frequency that can be accurately detected by the sensor. Too low tension leads to a lower frequency; too high a tension to a higher frequency. In order to evaluate the signals generated by the sensor, a control circuit connected to the sensors is provided. Unlike digital signal processing (see Fig. 4 and 5 ), which is necessary for the detection of a wire jump, the evaluation of analog signals is required to determine the wire tension.

• Detektion von Drahtsprüngen aus einer vorgegebenen Rille heraus
• Detektion von Lageveränderungen des Drahtes auf einem Drahtführungselement
• Detektion des Verschleißes eines Drahtführungselementes
• Detektion der Drahtspannung

In general, the exploited for the various monitoring tasks sensor signals such. B

• Detecting wire jumps out of a given groove
• Detecting changes in position of the wire on a wire guide element
• Detection of the wear of a wire guide element
• Detection of the wire tension

Used to immediately stop the sawing process in case at least one of the sensors indicates changing the position of the cutting wire on a wire guide disc To complete the sawing process and to replace worn wire guide elements before the start of a new sawing process or to register and evaluate only the detection result as part of the process parameter monitoring on the wire sawing device.

The sensor may also be implemented in one or more sensor devices to be mounted on the wire saw apparatus.

LIST OF REFERENCE NUMBERS

100

Wire Saw Device (Squarer)

110

Wire guide element in the form of a wire guide disk (arrangement of several wire guide disks on one axis forms a wire guide roller)

R1 to R10

Grooves in wire guide disc

120

Wire guide elements in the form of a deflection roller

121.121 *

Wire guide elements in the form of pulleys

122

Wire guide element in the form of a leading guide roller, also called guide roller

124

Wire guide element in the form of a cylindrical deflection roller, also called Umlenkzylinderrolle

125

Wire supply spool

130

Bracket for wire guide discs

135, 135 *

Sensor (mounted on bracket)

140

cutting wire

145

wire frame

Z

Pull direction of the cutting wire

V

wear groove

P0

optimal position (setpoint) for the cutting wire

P #

out of position

150, 160

Control circuit (different variants)

200

Body of crystalline material, such as e.g. Ingots or ingots

Claims (22)

A wire saw apparatus for cutting bodies (200) of crystalline material, the wire saw apparatus having a cutting wire (140) guided over one or more wire guide elements (110, 120, 121, 122, 124) and moved longitudinally under tension, characterized that
the wire saw device has at least one sensor (135, 135 *) arranged in a surrounding area (A) of at least one of the wire guide elements (110, 120, 121, 121 *, 122, 124) and which changes the current position of the cutting wire (140) relative to a position (P0) predetermined as an optimal position, transverse to the longitudinal axis of the cutting wire (140). Wire saw apparatus according to claim 1, characterized in that the respective sensor (135) is an inductive or magnetic and / or optical sensor. Wire saw apparatus according to claim 1 or 2, characterized in that the respective sensor (135) is designed as a proximity sensor with integrated preamplifier. Wire saw apparatus according to one of the preceding claims, characterized in that the wire guide elements are deflection rollers (120; 121, 122; 124) and / or wire guide disks (110). A wire saw apparatus according to any one of the preceding claims, characterized in that the respective sensor (135; 135 *) is adapted to detect a spatially resolved change in the current position of the cutting wire (140) to cause a change in state of the cutting wire (140) and / or the wire guide elements (120, 121, 122, 124), in particular wear to recognize. Wire saw apparatus according to one of the preceding claims, characterized in that the respective sensor (135; 135 *) is adapted to detect a time-resolved change in the current position of the cutting wire (140) in order to change the state of the cutting wire (140) associated therewith, in particular wear and / or change in tension, to recognize. Wire saw device according to one of the preceding claims, characterized in that the wire saw device is formed as a squarer (100), the block-like body of crystalline material, in particular bars (200) made of silicon, divided into several blocks or bricks, in particular by Cutting lumber cuts. Wire saw apparatus as Squarer (100) formed according to claim 7, characterized in that in the surrounding area (A) of each wire guide disc (110) at least one of the sensors (135) is arranged so that the sensor (135) detects whether the cutting wire (140) remains in the groove (R5) in which the cutting wire (140) is guided or in one other groove has jumped. Wire saw apparatus according to one of claims 4 to 6, characterized in that the wire saw device is designed as a wafer saw, the block-like body of crystalline material, in particular blocks, bricks or columns of silicon, divided into several slices or wafers, in particular cut by wire cutting laps or wire cutting loops. Wire saw device according to one of claims 4 to 9, characterized in that the surrounding area (A) determines the rolling and / or rolling area intended for the cutting wire (140) on or from the deflection roller (120, 121, 122; 124). and / or wire guide disk (110). Wire saw device according to one of claims 4 to 10, characterized in that the surrounding area (A) comprises all the grooves (R1, R5, R10) of the respective wire guide disk (110). Wire saw apparatus according to one of claims 4 to 11, characterized in that the respective sensor (135) is aligned with the cutting wire (140) guided in one of the grooves (R5). Wire saw apparatus according to any one of the preceding claims, characterized in that the sensors (135) are mounted on a frame (130) of the wire-sawing device (100) or on a holder attached thereto. Wire saw apparatus according to one of the preceding claims, characterized in that the wire saw device has a control circuit (150) connected to the sensors (135), which processes a sensor signal (S) coming from the sensor (135) and stopping it longitudinally moving cutting wires (140) controls, if at least one of the sensors (135) indicates changing the position of the cutting wire (140) to cause a change in state of the cutting wire (140) and / or the wire guiding elements (110; 120; 121; 122 124). Wire saw apparatus according to claim 14, characterized in that the control circuit (150) is integrated in a motor control for at least one electric motor drive for moving the cutting wires. Wire saw apparatus according to claim 14 or 15, characterized in that the control circuit (150; 160) has at least one comparator (151, 161) which compares the sensor signal (S, S ') with a predefinable threshold value. Wire saw apparatus according to any one of claims 14 to 16, characterized in that the control circuit (150) comprises at least a first circuit stage (155) which checks whether a short to ground of the respective cutting wire occurs. Wire saw apparatus according to one of claims 14 to 17, characterized in that the control circuit (150) at least one second circuit stage (156), which continuously checks the function of the respective sensor (135). Wire saw apparatus according to one of claims 14 to 18, characterized in that the control circuit (150, 160) has at least one linking stage (153, 163) which links a plurality of sensor signals together. A sensor device for a wire saw apparatus, comprising a cutting wire (140) guided over one or more wire guide elements (110, 120, 121, 122, 124) and moved longitudinally under tension, characterized in that
the sensor device has at least one sensor (135, 135 *) which is arranged in a surrounding area (A) of at least one of the wire guide elements (110, 120, 121, 121 *, 122, 124) and which changes the current position of the cutting wire (140) relative to a position (P0) predetermined as an optimal position, transverse to the longitudinal axis of the cutting wire (140). Sensor device according to Claim 20, characterized in that the sensor device has a control circuit (150) which is connected to the at least one sensor (135) and processes a sensor signal (S) coming from the sensor (135) and stopping it longitudinally moving cutting wires (140), if the at least one sensor (135) indicates changing the position of the cutting wire (140), controls an associated state change of the cutting wire (140) and / or the wire guide elements (120; 122; 124). Use of a wire saw apparatus for dividing bodies (200) from crystalline material, wherein the wire saw apparatus has a cutting wire (140) guided over one or more wire guide elements (110, 120, 121, 122, 124) and moved longitudinally under tension;
characterized in that
the wire saw device has at least one sensor (135, 135 *) arranged in a surrounding area (A) of at least one of the wire guide elements (110, 120, 121, 121 *, 122, 124) and which changes the current position of the cutting wire (140) relative to a position (P0) predetermined as an optimal position, transverse to the longitudinal axis of the cutting wire (140).

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