Title of Invention

A DEVICE FOR PROCESSING THE FINISH OF WORK PIECES .

Abstract

The invention relates to a device for the purpose of processing the finish of work pieces, which exhibit a feed unit (1) with a slide (2) and an NC-controlled drive (3), a motorized spindle unit (4) w ith a motor-driven tool spindle (5), as well as a force measurement device (6) for the purpose of measuring the contact pressure that is brought to bear upon the tool spindle in the course of processing a work piece. According to the invention, the motorized spindle unit (4) is seated on the slide (2) with resilient elements that accept the weight of the motorized spindle unit (4) and are movable only in the direction of processing. Preferably, the slide (2) is supported on leaf springs (7), which are oriented perpendicular to the direction of advance of the slide (2). The force measurement device (6) is arranged on the motorized spindle unit (4) and on the slide (2) between connective elements (8, 9).

Full Text

A DEVICE FOR PROCESSING THE FINISH OF WORK PIECES Specification: The invention relates to a device for the purpose of processing the finish of work pieces, which exhibits a feed unit with a slide and a drive that is NC-controlled, a motorized spindle unit with a motor-driven tool Soindle, as well as a device for measuring force for the purpose of measuring the force of contact pressure that is brought to bear upon the tool spindle in conjunction with the process ing of a work piece. It is known how to measure the force of the contact pressure that is brought to bear upon the tool spindle continually in the course of processing a work piece and to regulate, subsequently, the contact pressure of the processing tool on the surface of the work piece, by degrees, to a pre-determined limit a which an optimal removal of material occurs (DE 39 30 457 A1). Furthermore, in DE 197 38 818 A1, a process is described in which, depending upon deviations in the measurements and form of the geometry of the work piece, which are determined during the processing of the work piece, the contact pressure or rather, the feed, of the work piece to be processed is controlled. The tool support is equipped with a measuring device that exhibits a precision indicator and supporting elements. In processing the finish of work pieces that have small parts, for example, processing the finish on seating surfaces of fuel injector valves, on flat surfaces of miniature pressure sensors, or the like, precision-guided feeding motions of the rotating grinding tool are necessary in order to meet the high standards for retaining the dimensions and the surface quality of the processed work piece. The feed must be set in such a manner that the processing tool lies against the surface of the work piece that is to be processed with a defined force that can be adjusted in a finely sensitive manner. As a rule, contact forces of less than 100 N must be set and, in the case of very small work pieces, contact forces on an order of magnitude of 1 to 25 N must be set. It is the underlying task of the invention to indicate a device for processing the finish of work pieces that renders power-controlled feeding motions possible, with a contact pressure that can be adjusted with sensitivity and maintained with precision. The task is performed according to the invention in the case of a device having the structure described at the outset by virtue of the fact that the motorized spindle unit, with resilient elements that accept the weight of the motorized spindle unit and can be moved only in the direction of processing, is seated on the slide, and that the device that measures the force is arranged between connective elements on the motorized spindle unit and on the slide. The motorized spindle unit is preferably supported on leaf springs, which are oriented perpendicular to the direction of the slide's advance. The leaf springs, which are oriented vertically, mounted with a short exposed length, are very yielding and flexible in the direction of the spindle's advance, so that contact forces at the tool spindle are transferred to the device that measures the force in a manner that is sensitive and involves little loss. When mounted with a short exposed length, in particular, the leaf springs can accept great vertical forces as well as great transverse forces. Therefore, they lend themselves to supporting the motorized spindle unit on the slide, such that additional guides, which are subject to friction, are not necessary. The device for measuring the force is arranged between the resilient elements, for example, on the underside of the motorized spindle unit between the leaf springs or, in the direction of the work, it can be connected to the end of the motorized spindle unit that faces the rear. According to a preferred embodiment, the unit that measures the force exhibits a piezo element as a force sensor. The piezo element renders very precise measurements of force possible, with extremely low degrees of deformation. The use of other force sensors should not be precluded. Within the context 0f'the teaching according to the invention, expansion measurement strips or magneto restrictive sensors can be used as well. The force sensor, a piezo element for example is, according to a preferred embodiment form of the invention, arranged between two contact elements that exhibit spherical contact surfaces. The spherical contact surfaces are supported on annular or dish-shaped bearing surfaces of the connective elements, which are provided on the motorized spindle unit and the slide. In the case of this embodiment, it is assured that the force sensor is mounted in a manner that is devoid of transverse forces, and the contact forces that are brought to bear upon the tool spindle are transferred to the force sensor in a manner that exhibits little loss. In the process, pre-stressing the force sensor is to good effect. An advantageous embodiment of the force-measuring device makes provision for the embodiment of the contact elements in the form of bolts, such that one bolt exhib its a threaded borehole and the other bolt exhibits a longitudinal borehole, and the bolts are braced against the force sensor with a defined force of pre-tension by means of an expansion screw. Furthermore the connective element for the force measurement device, which is arranged on the slide is, to good purpose, arranged on a carrier, which is attached in guidance grooves of the slide in such a manner that it can be moved for adjustments. The device according to the invention renders a very precise and sensitive detection of those contact forces that are brought to bear on the working spindle in processing the finish of work pieces possible. The measurement values of the force are led to the NC control of the feed drive. With a high-resolution NC feediig of the slide, which is performed in a manner according to the state of the art, minima1 forces, forces defined within the range between 0.1 N and 10N, for example, can be brought to bear upon the work piece. In processing the finish of serially produced parts having small pieces, a surface of high quality is achieved in the process. In conjunction with a pathway measurement system that can be integrated into the device, it is possible, furthermore, to detect, by means of measurement technology, progress along the feed pathway over time. From, the measurement values of the force measurement device and/or the pathway measurement system, it is possible to derive control commands for the purpose of guiding the process in conjunction with the processing of the work piece. In what follows, the invention will be elucidated in greater detail by virtue of a drawing that represents just one embodiment example. Fig. 1 shows, schematically, a device for processing the finish of work pieces, Fig. 2 shows, schematically, an additional structural configuration of the device, in cutout fashion, and in a markedly enlarged representation, compared to Fig. 1, Fig. 3 shows, schematically, a view from above onto the object represented in Fig. 2. A feed unit 1, having a slide 2 and an NC-controlled drive 3, a motorized spindle unit 4 with a motor-driven tool spindle 5, as well as a device that measures force 6, for the purpose of measuring the contact pressure that is brought to bear upon the tool spindle 5 in conjunction with processing a work piece, are part and parcel of the fundamental structure of the device depicted in Fig. 1. The motorized spindle unit 4 is seated on the slide 2 by means of leaf springs 7, such that the leaf springs 7 are oriented perpendicular to the direction of advance of slide 2 and accept the weight of the motorized spindle unit 4. The force-measuring device 6 is arranged between connective elements 8, 9, on the motorized spindle unit 4 and on slide 2, and it is equipped with a piezo element as a force sensor 10. Slide 2 exhibits a precision slide guide 11 that is embodied in accordance with the state of the art, as well as a roller spindle 12 as the propulsion aggregate. Other embodiments of the feed unit 1, for example a linear drive, are not precluded. The mounting of the leaf springs 7, as well as the embodiment of the force measurement device 6, is depicted in greater detail in Figs. 2 and 3. The force sensor 10 is arranged between two contact elements, which are embodied as bolts 13, 13' in the embodiment example, and exhibit contact surfaces 14. The contact surfaces 14 are supported at annular or dish-shaped bearing surfaces of the of the sic] connective elements 8, 9. One of the bolts 13, exhibits a threaded borehole, the other bolt 13', a longitudinal borehole. The bolts, 13, 13', are pre-stressed, with a defined force of pre-tension, against the force sensor 10, which is arranged between the bolts 13, 13', by means of an expansion screw, 15. A pre-tension force between 100 and 200 N is to good purpose. From Figs. 2 and 3 one can derive, furthermore, that the connective element 9 on the same side as the slide is arranged on a carrier 16 for the force-measuring device 6, which is attached by means of tenon blocks 17 in guide grooves 18 of slide 2 so as to be capable of movement for the purpose of effecting adjustments. In the embodiment example shown in Figs. 2 and 3, the force measurement device 6 is connected to the rear end of motorized spindle 4, in the direction of the work. The two leaf springs 7, of which only the rearward leaf spring is depicted in Figs. 2 and 3, are attached with a short mounting length to carrier plates 19 and 20. which are attached to slide 2, or to the underside of the motorized spindle units. Securing pins 21 prevent inadmissibly great movements of the motorized spindle unit 4 when tool changes, for example, or other mounting work is done. The force measurement device 6, which is depicted, in Figs. 2 and 3, can also be arranged on the underside of the motorized spindle unit 4, between the leaf springs 7, as is schematically represented in Fig. 1. The device according to the invention can, in addition, be equipped with a device for measuring the length of the pathway 22, by means of which the course of the feed pathway over time can be determined by means of measurement technology. Control commands to direct the process in the processing of work pieces can be derived from the force measurement values and from the measurement values of the pathway measurement system. That will be explained in what follows by virtue of the examples. When the work piece is cut into, that is, when the tool makes contact with the work piece, the force-controlled feed rate of advance declines rapidly, such that the course of the curve, over time, flattens as the removal of material from the surface of the work piece increases. It is possible to derive criteria for the optimal management of a finish-processing process from the course of the feed pathway over time. Thus, the profile of the feed pathway over time can be used as a measure of the quality of the surface of the work piece. In the case of a prescribed contact pressure between the work piece and the processing tool, the force-controlled rate of feed reaches a rate that is approximately constant with increasing surface quality. By setting a value of ideal force within the described range of settings, between 0.1 and 100 N, it is possible to change the amount of material removed and the resultant rate of feed. In the case of an optimal force relative to the process, a higher surface quality is generally reached very constantly. The parameter adjustments can be optimized in such a manner that the desired surface quality is achieved with minimal processing time. From the course of the feed pathway ova: time, furthermore, it is possible to derive a signal value that characterizes the cutting behavior in order to add to a tool, to identify any breakage of a tool that might occur, or to identify tool wear. Furthermore, from the course of the feed pathway over time, it is possible to asce lain instabilities in the process. WE CLAIM: 1. A device for processing the finish of work pieces that exhibits a feed unit (1) with slide (2) and an NC controlled drive (3), a motorized spindle unit (4) with a motor-driven tool spindle (5) as well as a device for measuring forces (6) for the purpose of measuring the contact pressure that is brought to bear upon the tool spindle in the course of processing a work piece, characterized by the feet that the motorized spindle unit (4), with resilient elements that accept the weight of the motorized spindle unit (4) and are movable only in the direction of processing, is seated on the slide (2), and that the device that measures the force (6) is arranged on the motorized spindle unit (4) and on the slide (2) between connective elements (8,9). 2. A device as claimed in claim 1, wherein the fact that the motorized spindle unit (4) is supported on leaf springs (7) that are oriented perpendicular to the direction of advance of the slide (2). 3. A device as claimed in claim 1 or 2, wherein the fact that the device for measuring the force (6) s arranged between the resilient elements. 4. A device as claimed in claim 1 or 2, wherein the fact that the force measurement device (6) is connected to the end of the motorized spindle unit (4) toward the back in the direction of the axis. 5. A device as claimed in one of the claims 1 through 4, wherein the fact that the force measurement device (6) exhibits a piezo element as a force sensor (10). 6. A device as claimed in one of the claims 1 through 5, wherein the feet that the force measurement device (6) exhibits a force sensor (6) exhibits a force sensor (10) that is arranged between two contact elements and that the contact elements exhibit spherical contact surfaces (14) that are supported on annular or dish-shaped bearing surfaces of the connective elements (2). 7. A device as claimed in claim 6, wherein the fact that the contact elements are embodied as bolts (13, 130, such that one bolt (13) exhibits a threaded borehole and the other bolt (130 exhtoits a longitudinal borehole, and that the bolts (13, 13') are braced by means of an expansion screw (15) with a defined pre-tension against the force sensor (10), which is arranged between the bolts (13,13'). 8. A device as claimed in one of the claims 1 through 7, wherein the fact that the connective element (9) for the force measurement device (6), on the same side as the slide, is arranged on a carrier (16), which is attached in guide grooves (15) of slide (2), so as to be movable for the purpose of effecting adjustments. The invention relates to a device for the purpose of processing the finish of work pieces, which exhibit a feed unit (1) with a slide (2) and an NC-controlled drive (3), a motorized spindle unit (4) w ith a motor-driven tool spindle (5), as well as a force measurement device (6) for the purpose of measuring the contact pressure that is brought to bear upon the tool spindle in the course of processing a work piece. According to the invention, the motorized spindle unit (4) is seated on the slide (2) with resilient elements that accept the weight of the motorized spindle unit (4) and are movable only in the direction of processing. Preferably, the slide (2) is supported on leaf springs (7), which are oriented perpendicular to the direction of advance of the slide (2). The force measurement device (6) is arranged on the motorized spindle unit (4) and on the slide (2) between connective elements (8, 9).

Documents:

391-CAL-2002-(12-11-2012)-FORM-27.pdf

391-cal-2002-granted-abstract.pdf

391-cal-2002-granted-claims.pdf

391-cal-2002-granted-correspondence.pdf

391-cal-2002-granted-description (complete).pdf

391-cal-2002-granted-drawings.pdf

391-cal-2002-granted-examination report.pdf

391-cal-2002-granted-form 1.pdf

391-cal-2002-granted-form 13.pdf

391-cal-2002-granted-form 18.pdf

391-cal-2002-granted-form 2.pdf

391-cal-2002-granted-form 26.pdf

391-cal-2002-granted-form 3.pdf

391-cal-2002-granted-form 5.pdf

391-cal-2002-granted-pa.pdf

391-cal-2002-granted-reply to examination report.pdf

391-cal-2002-granted-specification.pdf