MXPA99002102A - Method and apparatus for computer numerically controlled pin grinder gauge - Google Patents

Abstract

A method and apparatus for grinding crankshafts or similar devices in which one of the crankpins of the crankshaft is machined and subsequent to this machine step, the actual dimension of the crankpin is measured. This measured value is compared to the projected value of the crankpin and the distance of travel of a grinding wheel in-feed is adjusted accordingly.

Description

METHOD AND APPARATUS FOR CRANKSHAFT DB RECTIFIER CALIBRATOR NUMERICALLY CONTROLLED BY COMPUTER DESCRIPTION OF THE INVENTION The present invention relates to a crankshaft rectifier calibrating system numerically controlled by computer (CNC) to ensure that the series of crankshafts, camshafts or similar axes and workpieces are properly rectified. The control of the size of the workpieces, which have been rectified by grinding machines, has traditionally been achieved by the exact control of the position of the axis of the grinding wheel, a rectifier system during manufacture or the feedback of a post- caliper process. Of these three methods, the gauge during manufacturing to control the movement of grinding wheel feed, has traditionally been the most accurate, since it directly measures the dimensions of the work piece being rectified and eliminates the need for machine control to compensate the thermal changes, the wear of the wheel, the errors of machine geometry and other variable processes. U.S. Patent 4,637,144 issued to Schemel is normally a calibrating tool during manufacture. This patent monitors the diameters of the trunnions during the treatment in the grinding machine and includes a guide 6 having a detector 4 and two sensors 3. These sensors are in the form of elongated arms or fingers with edges 5, which must be maintained in continuous contact with the peripheral surface IB of a journal 1 while the axis IA orbits or circulates along the path P. However, with the appearance of precision rectifying processes for parts which are not round, such as cams, and for round parts which are rectified while being rotated on an axis different from their geometrical center, new problems are introduced to adequately control the size of the work piece. The present invention describes a process and apparatus which can combine the elements, to calibrate in a post-process and calibrate during manufacture to control the size of the work piece, to a degree necessary for the production of automotive crankshafts and axes of cam. The problems inherent in the prior art are directed by the present invention which is directed to a CNC rectifier process for crankshafts of exact machinery having a number of trunnions which cause the generation of the trunnion geometry by movement or by an axis during the manufacture of a grinding wheel, while the crankshaft is rotated near its rotating shaft. Calibration during manufacture of the workpiece during grinding could require the gauge head to follow the stump through its rotation as shown in the Schemel patent. The present invention uses a calibrating head mounted on a grinding machine, which can measure the size of the trunnions in the work piece, being rectified at several points in a machine cycle. The 'movement of the grinding wheel, the rotation of the work piece and the movement of the gauge head are controlled by a microprocessor provided in the machine. The microprocessor contains a memory which includes the geometry and tolerances for the different parts of the work piece, which are rectified. Based on the current measured size of at least a portion of the workpiece, the movement of the grinding wheel is automatically controlled. These together with other objects of the invention, together with various characteristics of novelty which characterize the invention, are pointed out particularly in the claims together with, and forming part of, this description. For a better understanding of the invention, its operating advantages and the specific objectives obtained by its uses, reference should be made to the appended drawings and descriptive matter in which the preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective drawing of a grinding machine operating under the process of the present invention; FIGURES 2 and 3 are flow charts of the present invention; and FIGURE 4 is a block diagram of the control system for the present invention. FIGURE 1 illustrates a typical grinding machine 10 used to grind a crankshaft 22 or other work pieces, having a series of trunnions or other rectifiable parts. A standard rotating grinding wheel 12 that can be advanced or retracted from the crankshaft or work piece is used. Likewise, the work piece is fixed to the grinding machine in such a way that it allows its rotation, as well as allowing it to be advanced or retracted in the direction of the Z axis to allow several surfaces to be rectified by the grinding wheel 12. Several clamps 24 and 26 are used to fix the work piece in its proper position. A gauge 18 is fixed to a movable support 28, which will allow the gauge to contact a surface, such as a stump, which has been subjected to the grinding action of the grinding wheel 12. Lateral supports 14 and 16 are used to provide several connections used to move the journal support 28. It is noted that the longitudinal movement of the carriage moves the work along the Z axis to place the portion of the workpiece to be grinding in front of the grinding wheel 12 or the gauge 18. The gauge does not move along the axis Lateral X or vertical Y axis. The gauge 18 is provided with two movable grooves 20 which can allow the gauge to properly measure the size of a particular stump or other machined part. Figure 4 illustrates a typical microprocessor control 30 used to control the operation of the grinding machine 10. This control could include a controllable memory 34 such as an EPRO, EEPROM or similar memory, which could include several algorithms to operate the grinding machine as well as several parameters such as the size of each of the machined dies as well as the tolerances for each of these pins. The memory 34 is connected to a control device 32 which would control the operation of the gauge 18, the grinding wheel 12 as well as the rotation of the crankshaft during the grinding operation. Based on the measurements taken from one or more trunnions, the distance that the grinding wheel 12 must travel to rectify the measured trunnion or a subsequent trunnion should be altered.

Figures 2 and 3 illustrate the operation of a rectifier process according to the present invention. Initially, the memory 34 provided in the microprocessor control 30 is loaded with the specific size of each trunnion to be machined as well as the tolerances for each of these trunnions. In addition, an algorithm is included in the memory 34, which could alter the distance during the manufacture of the grinding wheel 12 based on the measured values of one or more trunnions. Once this information is provided in the memory, the grinding machine is cleared to accept a new workpiece, such as a crankshaft having a number of stubs which must be machined. A left-handed pusher should be anticipated to secure the stump against a right stop. Obviously, a right pusher should be used which could anticipate against a left stop with the crankshaft in between. Once the crankshaft is secure in place, an angular locator could rotate the crankshaft so that it is in its proper location so that the first pin is ground and subsequently measured by the gauge 18. Proximity switches are included in the grinding machine to ensure that the crankshaft is in its proper position, and whether the appropriate crankshaft or work piece has been inserted into the machine. If the crankshaft is not properly positioned, or if the wrong crankshaft has been inserted in the grinding machine, the automatic cycle of the grinding machine would be interrupted to force the intervention of the operator. Once the problem has been solved, the cycle could be restarted. The clamps that secure the crankshaft to the grinding machine would then be closed and the crankshaft rotation would be in a torque / slave mode. At this point, the angular locator would be retracted and the proper dimension of the first stump would be accessed from the memory 34. The grinding wheel 12 would be moved to its proper position to grind the first stump and a coolant to cool the grinding machine would be engaged. If the grinding machine is in its cold start mode, which means that it has been dormant for a period of time, the grinding wheel will rectify the core to a programmed size slightly larger than the finished projected size of the core. The grinding wheel is then retracted from its grinding position and the gauge 18 is moved to its position to measure the size of the first stump. The actual size of this stump is then compared to the projected size of the pin and the wheel feed is properly synchronized. This new wheel feed distance should be accessed within the memory 34 of the microprocessor 30 to subsequently control the movement of the grinding wheel 12. The gauge 18 is then retracted and the grinding wheel 12 is advanced to grind the first stump to its size . The grinding wheel 12 is then retracted and the crankshaft 22 is moved to its next position to grind the second journal. The pin adjustment information which has been obtained by comparing the projected sizes of the first stump to its size measured in the cold start mode, will be used to advance the grinding wheel 12 at a distance to rectify the second stump to its proper size . It should be noted that no measurement is made for the second stump. The grinding wheel is then retracted and the third journal is moved in position to be grinding by the grinding wheel 12. All subsequent dies are rectified in this manner. At this point, the first crankshaft is removed and a second crankshaft is inserted in its place and the machining of this crankshaft is continued in the cold start mode as outlined above. This cold start mode may continue with a predetermined amount of time or a predetermined number of crankshafts, such as five. It is noted that in the cold start mode, only the first of the stubs of any crankshaft are measured.

Once a predetermined number of crankshafts has been machined, or a predetermined time has elapsed, the grinding machine will start to operate in the normal mode. When the grinding machine is operating in the normal mode, the first crankshaft journal should be machined based on the measurement made with respect to the last stump measured. In this mode, the first journal of each of the crankshafts is machined without any measurement. Once the last crankshaft stump is machined by the grinding wheel 12 operating in the normal mode, the size of this stump is measured and compared to the projected size of this stump. If the measured size is equal to the projected size, the crankshaft is removed from the machine and a new crankshaft to be machined is inserted into the grinding machine. If the measured size is not equal to the projected size, but is within a particular tolerance, the distance of the grinding wheel during manufacture is adjusted by a certain percentage of the size error of this pin. It is observed that this last stump measured will not be rectified again. However, the distance of the grinding wheel during manufacture will be changed appropriately. However, if the difference between the projected stump size and the actual measured stump size falls beyond this tolerance, the rectifying machine will determine that a failure exists and production should be stopped until a correction is made to the machine. It is noted that when the grinding machine is operating in the normal mode, a measurement is made only at the last stump of a particular crankshaft. Alternatively, when the machine is operating in the normal mode, it would be unnecessary to measure each of the last trunnions of each crankshaft if the machine seems to be operating very close to the projected values of the trunnions. In this case, the measurements can be made to every second or third or fourth crankshafts, etc. It is important to note that the teachings of the present invention do not need to be used only when machining or grinding a work piece having a successive grinding surface number, which can be ground to the same dimension, but could be used if the piece of work includes only a single surface to be rectified. It will be understood that the invention is not confined to the particular construction and disposed herein and illustrated and described, but encompasses said modified forms thereof, which comes within the scope of the following claims.

Claims (21)

1. CLAIMS 1. A method for grinding a work piece, having one or more -surfaces, which are to be rectified to an equal dimension, by a grinding machine provided with a grinding wheel and a gauging gauge, characterized in that it comprises the steps of: accessing at least one algorithm as well as a series of parameters related to the workpiece to be rectified, in a memory provided in a microprocessor, used to control the grinding machine; insert and fix the workpiece in the grinding machine; advancing the workpiece to a position to grind a first surface of the workpiece; start the rotation of the work piece; advancing the grinding wheel from a starting position to the first surface; rectifying the first surface by advancing the grinding wheel to a first predetermined distance from such a starting position based on the information provided in the memory, the first predetermined distance is greater than the distance from the starting position to the first surface and less than the distance between the start position and the projected value, the predetermined distance is always less than the distance between the start position and the projector value, the rectification step removes material from the first surface to create a rectified surface; retracting the grinding wheel and stopping the rotation of the workpiece; advancing the measurement gauge to the ground surface to measure the amount of material removed in the rectification step to produce a measured value; retract the measuring gauge from the ground surface, - compare the measured value with the projected value; calculating a second advance distance for the grinding wheel and accessing the second distance in the microprocessor memory; and advancing the grinding wheel of the second distance to further rectify the second surface as the workpiece rotates. The method according to claim 1, characterized in that it also includes the steps of: subsequent to the advance of the grinding wheel, the second step of distance, advancing the work piece, to a position for grinding a second surface of the Workpiece; and advancing the grinding wheel of the second distance to rectify the second surface a. as the workpiece rotates. 3. The method of compliance with the claim
2. 2, characterized in that it also includes the steps of: subsequent to the advance of the grinding wheel, the second distance to rectify the stage of the second surface to successively advance the workpiece to all subsequent surfaces to be ground; successively advance the grinding wheel, the second distance to rectify each. one of the subsequent surfaces as the workpiece rotates; and remove the work piece from the grinding machine. 4. The method of compliance with the claim
3. 3, characterized in that it also includes the steps of: inserting and fixing a subsequent workpiece in the grinding machine; advancing the workpiece subsequent to a position to rectify a first surface of the subsequent workpiece;
4. start the rotation of the subsequent workpiece; advancing the grinding wheel to the first surface of the subsequent workpiece; grinding the first surface of the subsequent workpiece, advancing the grinding wheel to the second distance to remove the material from the first surface to create a grinding surface of the subsequent workpiece; retract the grinding wheel and stop the rotation of the workpiece; advancing the measuring gauge to measure the amount of material removed from the subsequent work piece in the pre-grinding step to produce a second measured value; retracting the measuring gauge from the ground surface of the subsequent workpiece; compare the second measured value with a second projected value; calculate a third advance distance for the grinding wheel and access the third distance in the memory of the microprocessor; and advancing the grinding wheel to the third distance to further rectify the rectified surface of the subsequent workpiece.
5. 5. The method according to claim 4, characterized in that it also includes the steps of: prior to the removal step, advancing the work piece to a position for grinding a second surface of the subsequent workpiece; and advancing the grinding wheel at the third distance to rectify the second surface of the subsequent workpiece. The method according to claim 5, characterized in that it further includes the steps of: prior to the removal step, successively advances the workpiece subsequent to all subsequent surfaces to be ground; and successively advancing the grinding wheel at the third distance to rectify each of the subsequent surfaces as the subsequent workpiece rotates. The method according to claim 1, characterized in that it further includes the steps of: rectifying a predetermined number of workpieces in the manner recited in claim 1; inserting and fixing a subsequent work piece in the grinding machine, the work piece is provided with a plurality of successive surfaces to be ground;
6. advancing the work piece to a position to rectify the first of the workpiece surfaces; start the rotation of the work piece; advancing the grinding wheel to the first surface; rectifying the first surface by advancing the grinding wheel a predetermined distance, determined by the last calculated stage; rectifying each of the successive surfaces of the work piece the same distance as the previous rectification step; Retracting the grinding wheel by the last of the successive surfaces after the last surface has been rectified; advancing the measuring gauge to measure the dimension of the last of the successive surfaces to produce a projected value; compare the measured value of the last one or the successive surfaces with the projected value of the last of the successive surfaces; recalculate a third advance distance for the grinding wheel and access the third distance in the memory of the microprocessor; and remove the work piece from the grinding machine. The method according to claim 2, characterized in that it further includes the steps of: rectifying a predetermined number of workpieces in the manner recited in claim 1; inserting and fixing a subsequent work piece in the grinding machine, the work piece provided with a plurality of successive surfaces to be ground; advancing the work piece to a position to rectify the first of the workpiece surfaces; start the rotation of the work piece; advancing the grinding wheel to the first surface; rectifying the first surface by advancing the grinding wheel a predetermined distance, determined by the last calculated stage; rectifying each of the successive surfaces of the work piece the same distance as the previous rectification step; Retracting the grinding wheel by the last of the successive surfaces after the last surface has been rectified;
7. advancing the measuring gauge to measure the dimension of the last of the successive surfaces to produce a projected value; compare the measured value of the last one or the successive surfaces with the projected value of the last one of the successive surfaces; recalculate a third advance distance for the grinding wheel and access the third distance in the microprocessor memory; and remove the work piece from the grinding machine. The method according to claim 3, characterized in that it further includes the steps of: rectifying a predetermined number of workpieces in the manner recited in claim 1; inserting and fixing a subsequent work piece in the grinding machine, the work piece provided with a plurality of successive surfaces to be ground; advancing the workpiece to a position to rectify the first of the surfaces' of the workpiece; start the rotation of the work piece; advancing the grinding wheel to the first surface;
8. rectifying the first surface by advancing the grinding wheel a predetermined distance, determined by the last calculated stage; rectifying each of the successive surfaces of the work piece the same distance as the previous rectification step; Retracting the grinding wheel by the last of the successive surfaces after the last surface has been rectified; advancing the measuring gauge to measure the dimension of the last of the successive surfaces to produce a projected value; compare the measured value of the last or the successive surfaces with the projected value of the last of the successive surfaces; recalculate a third advance distance for the grinding wheel and access the third distance in the rectifier memory; and remove the work piece from the grinding machine. The method according to claim 4, characterized in that it further includes the steps of: rectifying a predetermined number of workpieces in the manner recited in claim 1;
9. inserting and fixing a subsequent workpiece in the grinding machine, the additional workpiece provided with a plurality of successive surfaces to be ground; advancing the work piece to a position to grind the first of the surfaces of the additional workpiece; starts the rotation of the work piece; advancing the grinding wheel to the first surface; rectifying the first surface by advancing the grinding wheel a predetermined distance, determined by the last calculated stage; rectifying each of the successive surfaces of the additional workpiece, the same distance as the previous rectification step; Retracting the grinding wheel by the last of the successive surfaces after the last surface has been rectified; advancing the measuring gauge to measure the dimension of the last of the successive surfaces to produce a projected value; • compare the measured value of the last or the successive surfaces with the projected value of the last of the successive surfaces;
10. recalculate a third advance distance for the grinding wheel and access the third distance in the memory of the microprocessor; and remove the additional work piece from the grinding machine. The method according to claim 5, characterized in that it further includes the steps of: rectifying a predetermined number of workpieces in the manner recited in claim 1; inserting and fixing an additional workpiece in the grinding machine, the work piece provided with a plurality of successive surfaces to be ground; advancing the additional workpiece to a position to grind the first of the surfaces of the additional workpiece; start the rotation of the additional workpiece; advancing the grinding wheel to the first surface; rectifying the first surface by advancing the grinding wheel a predetermined distance, determined by the last calculated stage;
11. rectifying each of the successive surfaces of the work piece the same distance as the previous rectification step; Retracting the grinding wheel by the last of the successive surfaces after the last surface has been rectified; advancing the measuring gauge to measure the dimension of the last of the successive surfaces to produce a projected value; compare the measured value of the last one or the successive surfaces with the projected value of the last of the successive surfaces; recalculate a third advance distance for the grinding wheel and access the third distance in the microprocessor memory; and remove the additional work piece from the grinding machine. The method according to claim 6, characterized in that it further includes the steps of: rectifying a predetermined number of workpieces in the manner recited in claim 1; inserting and fixing an additional workpiece in the grinding machine, the additional workpiece provided with a plurality of successive surfaces to be ground;
12. advancing the additional workpiece to a position to grind the first of the surfaces of the additional workpiece; start the rotation of the work piece; advancing the grinding wheel to the first surface; rectifying the first surface by advancing the grinding wheel a predetermined distance, determined by the last calculated stage; rectifying each of the successive surfaces of the work piece the same distance as the previous rectification step; Retracting the grinding wheel by the last of the successive surfaces after the last surface has been rectified; advancing the measuring gauge to measure the dimension of the last of the successive surfaces to produce a projected value; compare the measured value of the last or the successive surfaces with the projected value of the last of the successive surfaces; recalculate a third advance distance for the grinding wheel and access the third distance in the microprocessor memory; and remove the work piece from the grinding machine.
13. 13. The method according to the claim

    2, characterized in that it also includes the steps of: inserting and fixing a workpiece in the grinding machine; rectify each of the surfaces of the work piece, advancing the grinding wheel a second distance.
14. 14. The method according to the claim

    3, characterized in that it also includes the steps of: inserting and fixing a work piece in the grinding machine; rectify each of the surfaces of the work piece, advancing the. grinding wheel a second distance.
15. 15. The method of compliance with the claim
16. 4, characterized in that it also includes the steps of: inserting and fixing a work piece in the grinding machine; rectify each of the surfaces of the work piece, advancing the grinding wheel a third distance. The method according to claim 5, characterized in that it also includes the steps of: inserting and fixing a workpiece in the grinding machine; rectify each of the surfaces of the work piece, advancing the grinding wheel a third distance.
17. 17. The method according to claim 6, characterized in that it also includes the steps of: inserting and fixing a workpiece in the grinding machine; rectify each of the surfaces of the work piece, advancing the grinding wheel a third distance. The method according to claim 3, characterized in that it also includes the steps of: inserting and fixing a workpiece in the grinding machine; • advancing such a work piece subsequent to a position to rectify a first surface of such subsequent workpiece; initiate the rotation of such subsequent workpiece; advancing the grinding wheel to the first subsequent workpiece surface;
18. grinding the first surface of the subsequent workpiece by advancing the grinding wheel a second distance; retract the grinding wheel and stop the rotation of the workpiece;
19. 19. The method according to the claim

    18, characterized in that it also includes the steps of: prior to the removal step, advancing the work piece to a position to rectify a second surface of the subsequent workpiece.
20. 20. The method of compliance with the claim

    19, characterized in that it also includes the steps of: prior to the removal step, successively, advancing the workpiece to all subsequent surfaces to be rectified. The method according to claim 1, characterized in that it further includes the step of moving the workpiece to a position to measure the dimension of the first surface after the surface is ground to the first predetermined distance.