EP3271111B1 - Method and grinding machine for grinding groove containing workpieces - Google Patents

Description

The invention relates to a method and a grinding machine for grinding grooves having workpieces according to the preamble of claims 1 and 6, such as GB 2 143 448 A known.

In the known methods and grinding machines for grinding grooves in workpieces, in particular helically or threaded workpieces are produced, the grinding wheel is profiled so that when grinding the groove in the workpiece, the outer positive shape of the profiling of the grinding wheel as a negative mold in Form of the groove formed in the workpiece. Even with the use of powerful and relatively long life CBN or diamond grinding wheels occurring at the profiling of the grinding wheel wear leads to a deterioration of the grinding result and, consequently, to a deviation from the desired shape of the groove in the workpiece, during the grinding process also reduce the accuracy of the profiling of the grinding wheel and its sharpness. As a result, the profiling of the grinding wheel has to be re-profiled after certain periods of use, d. H. must be trained.

As a very powerful dressing method for the profiling of the above grinding wheels, the crushing has prevailed. Crushing, which is often referred to as roll-forming, has long been established and proven to be a special method of rotary dressing for accurate profiling of metal- or ceramic-bonded diamond or CBN grinding wheels. Crushing is especially useful when large quantities of tools have to be provided with fine profiles.

The known crushers typically include crimping rollers which are either driven and frictionally drag the grinding wheel when both are engaged or disengaged, but the grinding wheel is such that when both are engaged, the grinding wheel by friction takes the Crushierrolle, ie can rotate. Because in recent years increasing tendency for ever larger and more powerful grinding machines with more powerful grinding spindle drives, the driving of Crushierrollen has prevailed by the driven grinding wheel, ie the Crushierrolle runs smoothly with, when the grinding wheel with the Crushierrolle is engaged. So that a high profiling accuracy can be achieved at the grinding wheel during crushing, the crushing parameters have to be selected and used with great care. After all, when the crushing roller and grinding wheel are engaged with each other, either whole grains from the profiling lining of the grinding wheel or at least larger fragments thereof are crushed or even torn out. When crushing, care must also be taken to ensure that the broken grains are removed as quickly as possible from the contact area between the crushing roller and the grinding wheel. The Crushiervorgang takes place at relatively high pressures in the engagement region of Crushierrolle and grinding wheel, so that is deformed by possibly occurring deformations of the grinding wheel, the profile to be formed during or after dressing. The parameters of Crushierrolle and grinding wheel in the strict sense or Crushierrollenspindel and grinding wheel spindle in the broader sense must therefore be selected and implemented so that the aforementioned deformations can be avoided or even excluded. If certain parameters such. B. the relative feed between the grinding wheel and Crushierrolle or in the engaging area of both resulting so-called Crushierdruck too large, a so-called chattering can occur, which is to avoid the Crushiervorgang under all circumstances.

In DE 30 50 373 C2 a dressing device for a numerically controlled profile or surface grinding machine is described. In this known dressing device, a Crushing device is arranged on the profile or surface grinding machine, which has its own drive. Provided is the dressing of a plurality of profiled grinding wheels, which are arranged in the direction of the axis of rotation side by side, so that each profiled grinding wheel is associated with a dressing roller. During the crushing, the dressing roll on the grinding wheel is rolled under pressure so as to crush and break up the abrasive grains, the peripheral speeds of the grinding wheel and the crushing roller being equal. By providing a dressing roller for crushing directly on the known grinding machine, the dressing can already be classified in the entire grinding process.

In DE 1 284 867 A is a universal grinding machine with turret described on which in the wheelhead a so-called curl device is provided, with which the required for forming or plunge grinding profile is rolled on the circumference of a grinding machine. The implementation of the curling process in terms of profiling in terms of Crushierens is not described. Although the profiling of the grinding wheel by means of this known curling device takes place on the actual grinding machine, it is additionally carried out in a single operation between grinding operations or turning, drilling, friction and thread cutting operations likewise carried out on the universal grinding machine.

In US 4,555,873 For example, a method and apparatus for grinding workpieces by means of a profiled grinding wheel are described. Also arranged on the grinding machine is a dressing device with which the shape and the sharpness of the grinding wheel can be restored. For this purpose, the grinding wheel is brought back into shape and sharpness between actual grinding operations with dressing rollers shaped in accordance with the profiling of the grinding wheel. It is also described in this document that dressing can be carried out continuously during interrupted grinding or during grinding. While there is no direct indication of crushing in this document, it is described that dressing should be considered as a process that can be performed continuously or discontinuously. Procedural separations of the dressing process are not described.

Furthermore, in DE 41 04 266 A1 a dressing machine for profiling a grinding wheel with a dressing wheel described. The described dressing of the grinding wheel, ie generating the required for the accuracy of the grinding result profiling of the grinding wheel with rounded at their faces dressing wheels, which are spatially pivoted so around the front side of the grinding wheel during dressing, that the profile to be achieved on the grinding wheel is generated , During the dressing process, the dressing wheel is in each case oscillated oscillatingly about a pivot axis which is arranged at a distance from its circumferential end face and extends transverse to the axis of rotation. In principle, the dressing wheel is moved up to the grinding wheel. In this known dressing the wear of the dressing wheel to be controlled.

In JP 05138532 A A dressing device for CBN grinding wheels is provided, which machines the grinding wheel so that it can be used equally well for pre-grinding as for finish grinding. The dressing wheel has so-called crushing grains and individual abrasive grains which are mixed in the dressing layer. The dressing takes place in one process and describes a dressing of axial end faces of a cup-shaped grinding wheel.

In US 3,435,814 a crushing device for crushing dressing of profiled grinding wheels is already described, which is fixedly mounted on a grinding machine. The crimping device is designed in the form of a crushing roller and is set against the grinding wheel for dressing it. A drive for the Crushierrolle should ensure that the peripheral speed of Crushierrolle and grinding wheel do not differ. When the crimping roller and the grinding wheel are engaged with each other, only the grinding wheel drives the crusher roller. The Crushiervorgang is carried out in one operation, and then the Crushierrolle is disengaged from the grinding wheel.

Also in the company brochure Winter of Saint-Gobain Abrasives it has already been described that a roll-in device used for dressing a profiled grinding wheel should as far as possible be part of the machine and be firmly installed on it. As a result, time-consuming tool changes can be avoided. Preferably, the grinding wheel should be driven and the profile roller smoothly be taken by this during dressing. Special profiling rollers are required for initial profiling as well as for subsequent profiling processes. In this known device, it is necessary that after profiling the profiling must be replaced. This has the disadvantage that positioning errors and thus profiling errors can occur on the grinding wheel.

It is common to all the already known dressing or crushing methods or crusher devices used that the crushing is neither carried out as a function of the grinding task, nor that the parameters of the actual crushing process guaranteeing high flexibility are taken into consideration.

The object of the present invention is therefore to provide a method and a grinding machine for grinding grooved workpieces, in which a crushing dressing of a grinding wheel to be profiled, taking into account substantial crushing parameters, is integrated into an automated grinding process and a high quality of the ground workpiece can be achieved in achieving a long service life of the grinding wheel.

This object is achieved by a method having the features according to claim 1 and by a grinding machine having the features according to claim 6. Advantageous developments are defined in the respective dependent claims.

According to a first aspect of the invention, a method of grinding workpieces having grooves is described. The workpieces are in particular helically or threaded workpieces, the grooves also straight grooves or radially circumferential grooves such. B. punctures can be. The workpiece is clamped and its groove is ground by means of a grinding wheel, which has a profiling which corresponds to the cross section of the groove. Due to the grinding process, as a result of wear of the grinding wheel can change their profiling, which is why the grinding wheel is reprofiled by crushing. Under Nachprofilieren here is a so-called Fertigcrushieren or Fertigprofilieren be understood. The profile is present on the grinding wheel and is restored in terms of accuracy and sharpness, so to speak. According to the invention, a Nachprofilier-Crushieren the grinding wheel thereby also driven Crushierrolle, by their control based on a measurement of speed and current consumption of the respective drives the grinding wheel and the Crushierrolle, based on a relative feed during Crushieren between the grinding wheel and the Crushierrolle takes place. The relative feed is preferably selected such that, for reasons of efficiency during crushing and during the entire grinding process, the relative feed is a maximum relative feed, at which no disadvantageous process conditions still occur. It is therefore nachprofilier-crushiert always with the maximum relative feed, in which on the one hand, the service life of the Crushierrolle is not excessively reduced, but can be operated with a relatively high Crushierdruck between the Crushierrolle and the grinding wheel, with Crushier always stable Crushierverhältnisse be maintained ,

According to the invention, at least rotational speed and current consumption are measured as essential crushing parameters for post-profiling crushing and used for controlling the process of crushing. The current consumption stands for the performance, which according to the requirements pull the drives both the grinding wheel and the Crushierrolle or the power which is to be supplied to them so that the desired, defined Crushierparameter can be met.

Preferably, a profiling Crushieren the grinding wheel by means of Crushierrolle, which is usually not driven, by controlling only the grinding wheel drive based on its measured speed and current consumption, the profiling Crushing is performed before the start of the grinding process. Under profiling-Crushing is to be understood that receives a not yet profiled grinding wheel in a first operation before the start of the actual grinding process by means of a Crushierrolle the profiling so that the grooves can be ground into the workpiece by means of this grinding wheel. Profilier-Crushieren corresponds to a Vorcrushieren or pre-profiling or rough profiling.

According to the invention, the profiling-crushing is carried out by means of the same crushing roller which is used for post-profiling-crushing. This is achieved in that the Crushierrolle several, preferably at least two tread grooves, which are applied as a negative mold for generating the positive profiling on the grinding wheel successively. The provision of several crushing grooves in the crushing roll has the advantage that a single crushing roll can be used for several crushing operations. Anyway, a crushing role Worked out groove by groove, so to speak. And only if the last Crushier groove further profiling of the grinding wheel, in particular by way of Nachprofilier-Crushierens for reasons of accuracy no longer allow this Crushierrolle must be replaced and possibly worked up again.

Also in profiling Crushing allows the measurement of speed and current consumption of the drive of the grinding wheel optimal performing the Crushiervorgangs means of a maximum relative feed, in which adverse process conditions such. As a rattle does not occur.

According to the invention, during profiling crushing, a larger dressing volume than the post profiling crushing is dressed by the grinding wheel.

It is thus to be noted that during profiling-crushing the grinding wheel is driven, whereas the crushing roller is usually not driven. However, it may be when crushing the trailing Crushierrolle that this undergoes a reduction in their speed due to slippage and other influences. For this purpose, it is provided that the Crushierrolle in at least short intervals, so to speak impulsively, their drive is switched on. However, the pulses of the connection of the drive are only so long or are only performed until the Crushierrolle has reached the rated speed again, which is the speed of the grinding wheel.

In a customary manner, the first side of the profiling on the grinding wheel is approached with a first groove profile flank, the approach to the first groove profile flank being monitored by an existing starting sensor system and a possibly occurring activation of the drive in the form of a drive pulse to the crushing roller. This is followed by the approach to a second flank of the arranged in the Crushierrolle groove, which is also monitored by the Anfahrsensik the possible successful connection of a drive pulse to the Crushierrolle. This is followed by a lateral process of the grinding wheel until the grinding wheel is moved on the profile center of the groove located in the Crushierrolle. This is followed by the feed movement between the grinding wheel and the Crushierrolle, ie the relative delivery between the grinding wheel and Crushierrolle, with driven grinding wheel and free-running Crushierrolle to. The maximum relative feed, ie the permissible feed during crushing, is realized by monitoring the current consumption and thus the grinding spindle power, whereby the current consumption is continuously measured. The CNC controller then calculates and sets the maximum relative feed, ie an optimum feed rate between the crushing roller and the grinding wheel, with regard to the efficiency of the crushing process.

If the grinding wheel has received its profiling during the profiling-Crushierens, then it can then be used in the normal grinding process for grinding the corresponding groove in the workpiece or re-used or post-profiling-crushed to increase the accuracy. Since the grinding wheel wears while the grinding wheel is worn, but the profile shape is essentially maintained within narrow limits, the grinding wheel must be crushed between the grinding sections to be determined on the basis of the wear rate of the profiling of the grinding wheel by re-profiling. A profiling crash is thus no longer required at this stage of the process.

In post-profiling crushing, both the grinding wheel and the crushing roller are each driven. As in the case of profiling-crushing, an edge of the groove in the crushing roller is first approached, whereby the process is monitored by the starting sensor system and the measurement of the power consumption at the two drives of the grinding wheel and the crushing roller (grinding spindle / crushing spindle). This is followed by a start of the second flank of the groove, wherein also by the starting sensor and the measurement of the power consumption of the two drives of the grinding wheel and the Crushierrolle, d. H. on whose spindles, this process is monitored. This is followed by a procedure of the grinding wheel on the profile center. The procedure differs from profiling-crushing in that during the after-profiling crushing, the grinding wheel and the crushing roller are driven and speed-controlled and, in addition, the power consumption is monitored in each case.

Preferably, the Crushierrolle and the grinding wheel with respect to their speeds are coordinated so that their peripheral speeds in the Nachprofilier-Crushieren in a defined by a peripheral surface of the Crushierrolle defined depth of the groove have a defined relationship to each other. As a result, the crushing process can be controlled while maintaining the essential process parameters for post-profiling crushing. And it ensures that an optimal Crushieren takes place, taking into account essential procedural parameters when Crushing.

Further preferably, the peripheral surface corresponding to the defined depth of the groove is in particular infinitely varied with respect to its depth in the groove with a constant ratio of the peripheral speeds of the grinding wheel and the crushing roller.

In the already mentioned during profiling Crushierens switching of drive pulses to the spindle of the Crushierrolle in their fall below a limit speed is now preferably set the limit speed or the Crushierrolle so long driven until the speed of the peripheral speed of the grinding wheel in the defined depth of the groove of the peripheral surface corresponds.

It is particularly important that during the crushing of the grinding wheel during the crushing in its engagement area so much coolant and in such an intensity is supplied that the broken grains and Schleifbelagteile can be removed quickly from the engagement area.

The at least machine parameter and crushing parameter-dependent maximum relative feed between the grinding wheel and the crushing roller during crushing is determined in particular by way of "trial and error" before the actual crushing and entered as limit value into a machine control and in particular also stored there.

According to a second aspect of the invention, a grinding machine provided for grinding grooved workpieces, in particular helical or threaded workpieces, conventionally includes a cross slide on a machine stand in X-axis direction and Z-axes Direction CNC-movable grinding headstock, which carries a profiled for grinding the groove grinding wheel, which is rotationally driven. The grooves can also be straight grooves or recesses. In addition, the grinding machine on a workpiece headstock with a C-axis. The workpiece is held on the grinding machine in one clamping. In addition, the grinding machine has a Crushing device permanently installed thereon with a crusher roller with its own rotary drive. The speed of the Crushierrolle is controllable by means of a control device. According to the Crushierrolle the grinding wheel for dressing their profiling is deliverable. The crushing roller has a profiling crushing section for profiling crushing the grinding wheel with a first dressing volume and a post-profiling crushing section disposed on the same crushing roller for post profiling crushing of the grinding wheel with a second dressing volume. By providing both a profiling crushing section and a post-profiling crushing section on one and the same crushing roller, not only can the crimping device be of relatively simple construction, but it can also be constructed to be particularly stable, because then the crushing roller is sufficiently stable, for example, due to a rigid bearing is that deformations are avoided in the actual Crushier process. These deformations can in principle occur due to the high forces occurring during the crushing process, which is why the crusher device with its attachment to the machine bed of the grinding machine also has to be made particularly rigid.

Preferably, the Crushierrolle more than two Crushierrillen or -nuten, which can be used successively in Crushieren the profiling of the grinding wheel until the last Crushierrille does not restore the required accuracy and sharpness of the profiling of the grinding wheel after Crushieren during Crushing. Then the Crushierrolle would be replaced. By providing a plurality of crushing grooves on one and the same crushing roller, after a groove on the crushing roller is worn, the next groove can be used for post-profiling crushing. This ensures that during the post-profiling crushing always a grinding wheel profile can be produced with optimum accuracy. This refers to post profiling crushing. The profiling-crushing is applied before grinding in such a case, when the grinding wheel has not profiled according to the groove to be produced formed on the workpiece. The profiling-Crushing is namely a so-called Erstprofile. In any case, during the entire grinding process on the grinding machine, only after-cycle crimping has to be carried out occasionally after specified cycles so that both the shape of the profiling and the sharpness of the grinding wheel are restored after a certain grinding time has been carried out.

So that the stability and rigidity of the crimping device can be ensured in or on the grinding machine, the crusher device is preferably arranged in a stable housing and fixedly connected to the machine stand. This makes it possible to reliably absorb the forces occurring during crushing and to avoid even an elastic deformation of the Crushing during Crushierens as far as possible.

Preferably, the Crushiereinrichtung has a CNC-controlled drive, which is connected via a coupling with the Crushierrolle to the rotary drive. Preferably, the Crushierrolle from high-speed steel (HSS) or carbide. The electric drive has the advantage that it can be reliably unlocked in particular in the case of profiling Crushierens, ie travels idle, which is particularly the case for profiling-Crushing the case because there usually the Crushierrolle is not driven, ie at Engaging the grinding wheel in the groove or groove of the Crushierrolle with the grinding wheel. The electric drive of the Crushierrolle has also the advantage that in the case of lowering the speed of the Crushierrolle the drive can be switched by switching pulses on the connection of the drive torque briefly until the rotational speed of the Crushierrolle again that of the grinding wheel corresponds and then the Crushierrolle again runs without drive with the grinding wheel.

Preferably, the Crushing device additionally comprises a structure-borne sound sensor, by means of which the engagement contact between the Crushierrolle and the grinding wheel can be monitored, wherein by means of the structure-borne sound sensor, a signal detecting the engagement contact is available to the control device, so that the control device, a signal via the engagement contact can be fed.

Preferably, the grinding wheel or the grinding spindle with the headstock is designed such that it can be moved to the crumbling roller during post-profiling crushing and can be moved in the transverse direction to the post-profiling crushing section. When Crushing namely a flank of the profile of the grinding wheel is usually approached first and something crushed, followed by the start and slight crushing of the second flank and then followed by the center in the groove running Nachprofilier-Crushieren.

Preferably, the Crushierrolle is formed in one piece or two parts. While the one-piece construction with the provision of multiple crushing grooves for multiple crushing a grinding wheel during an entire grinding process for high rigidity, which is required for the Crushieren brings benefits, the bipartite Crushierrolle is particularly advantageous if only a part of the Crushierrolle because of their Wear must be replaced, the not yet worn part, however, can be used. This may provide an advantage in terms of flexibility.

Finally, the control device is preferably designed in such a way that a maximum relative feed between the grinding wheel and the crushing roller can be realized during crushing in such a way that this maximum relative feed is smaller than a predeterminable, machine and process parameter-dependent limit value, which is before Crushing in the controller can be entered. This maximum relative feed is to be determined separately for each workpiece, for each execution of crushing rollers and grinding wheel and corresponding grinding conditions, including the abrasive pads used and the material of the crushing roller preferably in the context of "trial and error" experiments.

In the present case of the invention, the skilled person is at least given the doctrine essential process parameters for the control of this maximum relative feed, ie the maximum allowable feed without unmanageable process conditions adverse type occur with the grinding machine respected or realized can. With reasonable effort, the competent expert can determine this limit by testing. Once this limit has been determined, it is possible, by means of the control device, to approach the limit as close as possible to this limit, without this limit being exceeded. Thus, a fast and cost-effective crushing of grinding wheels with high accuracy in the fully automatic process is feasible.

• Figur 1 eine prinzipielle vereinfachte Darstellung einer Schleifmaschine mit Crushiereinrichtung in Draufsicht;
• Figur 2 ein Crushiereinrichtung und zugeordnete Schleifspindel mit Schleifscheibe gemäß der Erfindung;
• Figur 3 eine Crushierrolle mit zugeordneter Schleifscheibe für ein Profilier-Crushieren;
• Figur 4 eine Detailansicht von Crushierrolle und zugeordneter Schleifscheibe bei unmittelbarem Beginn des Profilier-Crushierens;
• Figur 5a) der Crushiervorgang der Profilierung an der Schleifscheibe an einer ersten Flanke;
• Figur 5b) der Crushiervorgang der Profilierung an der Schleifscheibe an einer zweiten Flanke der Crushierrolle;
• Figur 5c) der Crushiervorgang im Wesentlichen am Ende des Crushierens der Profilierung an der Schleifscheibe mittels der Crushierrolle; und
• Figur 6 die geometrischen Verhältnisse von Nuttiefe und entsprechend der Nuttiefe vorgesehene Umfangsfläche in der Nut und in der Profilierung der Schleifscheibe.

Further advantages, applications and details will now be explained in detail with reference to embodiments in the accompanying drawings. In the drawing show:

• FIG. 1 a simplified schematic representation of a grinding machine with Crushing in plan view;
• FIG. 2 a crusher and associated grinding wheel with grinding wheel according to the invention;
• FIG. 3 a Crushierrolle with associated grinding wheel for a profiling Crushieren;
• FIG. 4 a detailed view of Crushierrolle and associated grinding wheel at the onset of Profilier-Crushierens;
• FIG. 5a ) the Crushiervorgang the profiling on the grinding wheel on a first edge;
• FIG. 5b ) the Crushiervorgang the profiling on the grinding wheel on a second edge of the Crushierrolle;
• FIG. 5c ) the crushing operation substantially at the end of crushing the profiling on the grinding wheel by means of the crushing roller; and
• FIG. 6 the geometric relationships of groove depth and according to the groove depth provided peripheral surface in the groove and in the profiling of the grinding wheel.

In FIG. 1 is shown in a schematic representation in plan view, the arrangement of the essential components of a grinding machine on the machine bed. A workpiece headstock with a workpiece spindle with a C-axis has a workpiece 1 clamped. For optionally required clamping of the workpiece on tips a displaceable tailstock 4 is provided with a tip in extension of the longitudinal axis of the workpiece spindle. On a mounted on the machine bed cross slide a wheel spindle with grinding spindle is arranged, on which a grinding wheel 5 is fixed. The grinding wheel 5 has a profiling, with which the corresponding grooves are ground into the workpiece 1. For this purpose, the grinding wheel can be moved in the X, Z, and Y directions via CNC axes and fed to the workpiece 1. Furthermore, a crimping device 7 is provided, which carries a crushing roller. The axes of rotation of the Crushierrolle and the grinding wheel 5 are arranged parallel to each other, at least if the grinding wheel 5 is crushed with respect to their profiling.

In FIG. 2 are in the form of a section of the basic arrangement on the grinding machine according to FIG. 1 only the grinding spindle 2 with the grinding wheel 5 and associated therewith the crusher 7 with its crushing roller 8 shown. To the corresponding grooves in the in FIG. 2 The grinding spindle 2, with its grinding wheel 5, can be pivoted about a CNC-controlled A-pivot axis. In addition, the grinding spindle is also CNC-controlled in the Z and Y directions.

The in FIG. 2 shown basic construction of the crimping device 7 is characterized by a high rigidity, which z. B. it is clear that the Crushing device 7 is arranged in a housing 9 in which the Crushierrolle 8 carrying Crushierspindel 16 is rigidly mounted on both sides of the Crushierrolle 8 by means of rolling bearings 12. The drive motor 11 of the crusher 7 is also CNC-controlled and is connected via a coupling 10 with the Crushierspindel 16.

Shown is in FIG. 2 a Crushierrolle 8 according to the invention, which has two Crushierrillen or Crushiernuten or Crushiernuten. Both Crushiernuten can be used sequentially to Crushieren the profiling of the grinding wheel 5. On the one hand, this can be a profiling-crushing with the first crushing groove and a post-profiling-crushing with the second crushing groove. On the other hand, it is also possible that the two Crushiernuten the Crushierrolle 8 are used only for Nachprofilier-Crushieren. In this case, the in FIG. 2 Crushing groove shown above first used for Nachprofilier-Crushieren until it can no longer produce the required accuracy of the profiling on the grinding wheel 5. Subsequently, the crushing groove underlying in the drawing is applied to a further post-profiling crushing of the grinding wheel. Thus, when the two crushing grooves are used for post-profiling crushing, the service life of the crushing roller when crushed can be doubled with respect to a crushing roller having only a single crushing groove. It is also possible to use or provide a larger number of Crushiernuten in Crushierrolle invention. In any case, with the Crushierrolle invention above all, the higher stiffness so far into account and higher process accuracy in the crushing of the profiling of the grinding wheel and thus a higher accuracy of the workpieces to be ground can be achieved if the at least two Crushiernuten are arranged on a one-piece and thus rigid Crushierrolle 8.

In FIG. 3 of the squeezer 7, only the main part thereof, the crushing roller 8, which is arranged on the crushing spindle 16, is shown. The crushing roller 8 has a profiling crushing section 14 and a post-profiling crushing section 15. In addition, a structure-borne noise sensor 13 is provided on the Crushing device 7, by means of which the engagement contact of the grinding wheel 5, which is arranged on the grinding spindle 2 and driven in rotation about its C-axis, with the Crushierrolle 8 can be detected or monitored.

In the FIG. 3 illustrated grinding wheel 5 is not yet profiled and therefore must first be profiled-crushed for the actual grinding process. Under profiling-Crushieren in the context of generating the actual profiling on the grinding wheel 5 is to be understood. This is carried out in a profiling crushing groove 14 provided on the crushing roll 8 for profiling-crushing. For this purpose, the first before the profiling Crushing with her in cross-section deviating from the profile shape designed grinding wheel is first employed on a flank of the profiling Crushierabschnittes 14 Crushiernut and crushed to a small extent. In the second step, a slight crushing is then performed on the second flank of the profiling crush groove 14. Subsequently, the grinding wheel is moved into the middle of the groove of the Crushierrolle, and both flanks are then profiled-crushed at the same time. After the profiling crushing, the grinding wheel is post-profiled-crushed, whereby the grinding wheel receives its final profiling shape with very high accuracy.

In the FIG. 3 In contrast, Nachprofilier-Crushiernut 15 also shown, however, is used only during the actual grinding process when the profiling of the grinding wheel 5 nachprofilier must be crushed, because their shape no longer corresponds to the desired shape and because their sharpness must be resharpened.

The structure-borne sound sensor 13 responds at each contact of the profile 6 to be produced of the grinding wheel 5 on one of the flanks of the Crushiernuten 14, 15 and thus monitors the engagement contact during Crushieren. The first just trained grinding wheel 5 is thus by the FIG. 3 shown profiling crushing groove 14 crushed into a sharp profile, which is provided for thread grinding. By separating the crushing sections into a profiling crushing section 14 and a post-profiling crushing section 15, their service life can be increased because of otherwise heavy wear to which the crushing roller 8 is normally subject. The Nachprofilier-Crushiernut 15 provided for Nachprofilier-Crushieren 15th ensures the production of a profiling 6 on the grinding wheel 5 for a high-precision production of the grooves in the workpieces.

At the in FIG. 4 shown state of the straight-beginning of Crushierens just trained grinding wheel 5, this is driven by its grinding spindle 2, whereby the non-driven Crushierrolle 8 on the Crushierspindel 16 because of the engagement contact of just dressed grinding wheel 5 in the profiling Crushiernut 14 Crushierrolle by the grinding wheel is driven and runs along with this. An independent drive the Crushierrolle 8 does not take place, ie either the drive is turned off, or the clutch 10 (s. Fig. 2 ) between drive and crushing roller is set to "disconnected". Also shown again in FIG. 4 the structure-borne sound sensor 13, which registers or monitors the engagement contact of the grinding wheel 5 in the profiling crushing section 14. The signal which the structure-borne noise sensor 13 generates when the grinding wheel 5 comes into contact with the crushing roller 8 represents the monitoring that the grinding wheel 5 has actually made contact with the crushing roller 8 and the crushing process begins.

Since the grinding wheel 5 has a concentricity error in the usual way, the crushing roller 8 is not fully driven when first touched by the grinding wheel 5. As a result, the speed of the crushing roller 8 can drop. When a predetermined lower limit speed is reached, the drive motor 11 of the Cruhierspindel 16 can be added pulse-like. This connection takes place until the Crushierrolle 8 again has the speed which the grinding wheel 5 has. Ie. the drive pulse is carried out until the Crushierrolle 8 has their speed of the grinding wheel 5 corresponding target speed.

In the FIGS. 5a ), b) and c) the different phases when crushing the profiling 6 of the grinding wheel 5 are shown. In general, this procedure is implemented during the crushing, namely during profiling-crushing as well as after-profiling-crushing. The FIGS. 5a) to 5c ) exemplify the post-profiling crushing process. In FIG. 5a ) is shown how first a first edge of the profiling 6 of the grinding wheel 5 is approached on a first flank of the Nachprofilier-Crushiernut 15 in the Crushierrolle 8 and slightly crushed. To make the contact between the grinding wheel 5 and the crushing roller 8, the grinding wheel 5 can be moved along its CNC-controlled Z and Y axes. This ensures that during crushing optimum crushing parameters are maintained or realized with regard to relative feed, crushing forces and other parameters. In FIG. 5b ) It is shown how the laterally moved grinding wheel 5 is set with its edge of the profiling 6 opposite the first flank to the second flank formed on the post-profiling crushing groove 15 and subjected there to the starting operation and low crushing becomes. Analogous to FIG. 5a ) for the start of the first flank, the grinding wheel 5 is moved to approach in their CNC-controlled Z and Y axes in order to comply with the required and permissible Crushierparameter.

If both flanks of the profiling 6 of the grinding wheel 5 have been set individually in the post-profiling crushing groove 15 and slightly crushed, the grinding wheel is moved in the Y direction, ie the transverse direction, so that the profiling is arranged centrally to the crushing groove 15. This is in FIG. 5c ). Crushing both flanks at the same time represents the last step of crushing the profiling 6 of the grinding wheel 5. In the present case, this is again illustrated by the example of post-profiling crushing. In the same way and in the same sequence, this is done for the profiling-crushing by means of the in FIG. 5c ) Profilier-Crushiernut 14 also shown the Crushierrolle 8 performed.

In FIG. 6 For example, the geometric relationships between the crushing groove 15 of the crushing roller 8 and the profiling 6 of the grinding wheel 5 are shown with respect to two different levels with respect to the depth of the crushing groove 15. The fact that both the grinding spindle and the Crushierspindel are provided with separate separately controlled speed controls, it is possible to specify exactly on which "level" the peripheral speed of the Crushierrolle 8 and the grinding wheel 5 equal should be. It should be noted that the grinding wheel 5 and the crushing roller 8 have different diameters. The term "plane" is to be understood as the annular peripheral surface 17. She is only mentally referring to FIG. 6 in which this "plane" is represented for a single radius, referred to as "plane". The up to the drawn circumferential surface 17 within the Crushierrolle 8 encircling associated radius spans, so to speak, the annular, cylindrically shaped peripheral surface 17. Taking into account the different diameters of the crushing roller 8 and the grinding wheel 6, different rotational speeds are realized on the grinding wheel 5 of the crushing roller 8 such that, relative to a selected plane, the rotational speeds, ie the peripheral speeds, are constant. The ratio of these peripheral speeds is therefore 1: 1. Upon displacement of this imaginary peripheral surface 17 during the Crushsiervorganges, in particular continuously, the quality of the profiling 6 of the grinding wheel 5 can be further increased after the Crushiervorgang, whereby the grinding result can be improved on the workpiece.

LIST OF REFERENCE NUMBERS

1

workpiece

2

Wheelhead

3

Workhead

4

tailstock

5

grinding wheel

6

Profiling grinding wheel

7

Crushiereinrichtung

8th

Crushierrolle

9

Housing crusher device

10

Clutch Crushing device

11

Drive crusher device

12

Rolling bearing Crushing device

13

Acoustic emission sensor

14

Profiling crushing groove / profiling crushing section

15

Post-profiling crushing groove / after-profiling crushing section

16

Spindle crusher device

17

peripheral surface

18

machine control

Claims (13)

1. Method for grinding grooved workpieces (1) with a profiling (6) of a grinding wheel (5) formed so as to correspond to the cross section of the groove, by means of which the groove is ground into the workpiece (1) while it is clamped, wherein the profiling (6) of the grinding wheel (5) is crush-dressed, wherein a reprofiling/crush-dressing of the grinding wheel (5) is carried out by means of a thereby driven crush-dressing roller (8), wherein its control is in each case performed on the basis of a measurement of the rotational speed and current consumption of the respective drives of the grinding wheel (5) and the crush-dressing roller (8), and a relative advancement between the grinding wheel (5) and the crush-dressing roller (8) during the crush-dressing is controlled on the basis of this measurement,
   characterized
   in that
   a greater truing volume is removed from the grinding wheel during the profiling/crush-dressing with a profiling/crush-dressing portion of the crush-dressing roller than during the reprofiling/crush-dressing with a reprofiling/crush-dressing portion arranged on the same crush-dressing roller.
2. Method according to Claim 1, characterized in that a profiling/crush-dressing of the grinding wheel (5) is performed by means of the thereby at most only temporarily driven crush-dressing roller (8) by controlling the grinding wheel drive on the basis of its measured rotational speed and current consumption and by controlling the relative advancement between the grinding wheel (5) and the crush-dressing roller (8) on the basis of this measurement, wherein the profiling/crush-dressing is carried out before the beginning of the grinding process.
3. Method according to Claim 1 or 2, characterized in that, for crush-dressing, the grinding wheel (5) is infed to the crush-dressing roller (8) and brought into engagement with it, wherein, during the profiling/crush-dressing, the crush-dressing roller (8) runs along freely with the grinding wheel (5) without any effective drive (11) of its own.
4. Method according to one of Claims 1 to 3, characterized in that coolant is supplied to the crush-dressing roller (8) and the grinding wheel (5) at its region of engagement during the crush-dressing.
5. Method according to one of Claims 1 to 4, characterized in that a maximum relative advancement between the grinding wheel (5) and the crush-dressing roller (8) during the crush-dressing is dependent on machine parameters and crush-dressing parameters and is determined before the crush-dressing and input as a limit value into the machine control, in particular is stored there.
6. Grinding machine for grinding grooved workpieces (1), which has a grinding spindle head (2), which is movable under CNC control on a cross slide over a machine support in the direction of the X axis and the Z axis and holds and rotationally drives a grinding wheel (5) profiled for grinding the groove, and a workpiece spindle stock (3) with a C axis, wherein the workpiece (1) is held in a clamping set-up and, in addition, a crush-dressing device (7) fixedly installed in the grinding machine and comprising a crush-dressing roller (8) that has a rotary drive (11) of its own and can be controlled by means of a control device is provided, wherein the grinding wheel (5) and the crush-dressing roller (8) can be driven and controlled in their rotational speed during the reprofiling/crush-dressing,
   characterized
   in that, for truing its profiling (6), the grinding wheel (5) can be infed to the crush-dressing roller (8) and the crush-dressing roller (8) has a profiling/crush-dressing portion (14) for profiling/crush-dressing the grinding wheel (5) with a first truing volume and a reprofiling/crush-dressing portion (15), arranged on the same crush-dressing roller (8), for reprofiling/crush-dressing the grinding wheel (5) with a second truing volume.
7. Grinding machine according to Claim 6, characterized in that the crush-dressing device (7) is arranged in a housing (9) and is fixedly connected to the machine support.
8. Grinding machine according to Claim 6 or 7, characterized in that the crush-dressing device (7) has a CNC-controlled drive (11), which is connected by way of a coupling (10) to the crush-dressing roller (8), consisting in particular of high-speed steel or hard metal, for the rotational driving thereof.
9. Grinding machine according to one of Claims 6 to 8, characterized in that the crush-dressing device (7) has a structure-borne sound sensor (13), by means of which, when the grinding wheel (5) is in engagement with the crush-dressing roller (8), a signal can be delivered to the control device and used as a basis for determining the engagement contact between the crush-dressing roller (8) and the grinding wheel (5) for the monitoring thereof.
10. Grinding machine according to one of Claims 6 to 9, characterized in that, during the reprofiling/crush-dressing, the grinding wheel (5) can be infed to the crush-dressing roller (8) and can be moved in the transverse direction in relation to the reprofiling/crush-dressing portion (15).
11. Grinding machine according to one of Claims 6 to 10, characterized in that, at the beginning of and/or during the profiling/crush-dressing, drive pulses that can be activated when there is a drop in the rotational speed of the drive (11) of the crush-dressing device (7) can be fed to it.
12. Grinding machine according to one of Claims 6 to 11, characterized in that the crush-dressing roller (8) is formed as one part or as two parts.
13. Grinding machine according to one of Claims 6 to 12, characterized in that the control device is formed in such a way that a maximum relative advancement between the grinding wheel (5) and the crush-dressing roller (8) during the crush-dressing is less than a predeterminable limit value dependent on machine parameters and process parameters, which can be input into the control device before the crush-dressing.

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