JP2004114279A - Super-finishing device for raceway ring of ball bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a super-finishing device for a raceway ring of a ball bearing that performs rough machining always for an optimal period in response to roughness variation of a raceway surface in the previous process, finishes the finishing machining always at the optimal time in response to the loading state of a grinding wheel, reduces cycle time, extends the service life of the grinding wheel, and stabilizes quality of the finished surface at a high level. <P>SOLUTION: The super-finishing device comprises a force detecting means 7 for detecting a force in the support direction acting on a shoe 1 via a raceway ring W<SB>O</SB>during machining, and a control means 24 for determining a switching time between the rough machining and the finishing machining based on the detection output and a completion time of the finishing. By switching from the rough machining to the finishing machining based on the dressing/loading state of the grinding wheel or by completing the finishing machining, an optimal machining cycle responsive to the state of the raceway surface W<SB>OT</SB>in the previous process or the surface state of the grinding wheel is realized. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a superfinishing device for superfinishing a raceway surface of a ball bearing.
[0002]
[Prior art]
As a superfinishing device for superfinishing the raceways of ball bearings, that is, the raceways of the inner ring and the outer ring, generally, a superfinished grindstone is pressed against the raceway surface while rotating the raceway which is the workpiece. Swing while swinging. In such a super-finishing apparatus, a rough processing and a finishing processing are generally performed in order in one cycle, so that a rough processing including a surface roughness portion generated on a raceway surface by a grinding process which is a preceding process is performed. It has been practiced to remove the surface layer and to improve the surface roughness of the raceway surface to improve the surface accuracy in the subsequent finishing.
[0003]
Here, the rough processing and the finishing processing are realized by making the processing conditions different from each other, and the finishing processing has a higher rotation speed and a smaller number of swings of the workpiece than the rough processing performed earlier. The pressing force of the grinding wheel is set to be small.
[0004]
Conventionally, such roughing and finishing are performed by setting the time for each of them using a timer (for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-6-79616 (Pages 1 to 5, Table 1)
[0006]
[Problems to be solved by the invention]
By the way, in roughing and finishing in super-finishing, the grindstone needs to be dressed in order to remove the surface layer of the workpiece in roughing to some extent, and in finishing, the surface roughness is even smaller than in roughing. The grindstone needs to be in a clogged state in order to do so. Therefore, in this type of processing, in roughing, the grindstone clogged in the finishing processing of the previous cycle is dressed using the surface roughness of the workpiece, and in the finishing processing, the grindstone is again in a clogged state. In such a manner, the grindstone and the respective processing conditions are set.
[0007]
However, in the conventional super-finishing device, the roughing and the finishing are each set to a fixed time by a timer, so that the surface roughness of the raceway sent from the grinding process, which is the preceding process, is reduced. Irrespective of the variation and the clogged state of the grinding wheel, roughing and finishing are performed for a fixed time at a time, and the loss of time due to performing roughing more than necessary and the reduction of the life of the grinding wheel due to the falling off of abrasive grains are reduced. There is a problem that this occurs, and that there is a problem that the quality of the raceway surface is reduced by performing the finishing work more than necessary.
[0008]
The present invention has been made in view of such circumstances, and in accordance with the unevenness of the raceway surface in the previous process, rough processing is always performed only for an optimal time, and according to the state of clogging of the grindstone. For ball bearing bearing rings that can always finish finishing at the optimal time, thereby shortening cycle time and improving grinding wheel life, and stabilizing the quality of the finished surface at a high level. It aims to provide super finishing equipment.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the ball bearing super-finishing device of the present invention is a ball bearing race ring super-finishing device. A super-finishing device for the raceway surface, wherein the super-finishing device for a race of a ball bearing performs roughing and finishing in order of different machining conditions during one cycle. A force detecting means for detecting a force acting on the shoe in the supporting direction through the control means, and a control means for determining a switching time point between the rough processing and the finishing processing and an end time point of the finishing processing based on the force detection output. It is characterized by having (claim 1).
[0010]
Here, in the present invention, the control means determines a point in time at which the difference between the force detection outputs during the reciprocation of the grindstone near the swinging end of the grindstone increases and reaches a preset first value. It is configured to operate as a reference point for switching from the rough processing to the finishing processing, and to set a time point when the second value smaller than the first value is reached as a reference point for finishing the finishing processing. (Claim 2) is preferred.
[0011]
The present invention has been made as a result of the finding that the behavior of pressurization by a grindstone changes in accordance with the dressing / clogging state of the grindstone during superfinishing of the raceway surface of a ball bearing, that is, the annular groove. .
[0012]
That is, when the super-finishing wheel is rocked while pressing the raceway surface of the ball bearing with a certain pressure, the detection signal of the pressing force against the raceway surface of the grinding wheel is determined according to the sharpness of the grinding wheel, that is, the sharpening / clogging state. A different pattern was revealed by the present inventors' research. In particular, the difference in the pressing force pattern during the processing is remarkable near the swinging end of the grinding wheel, and a phenomenon occurs in which the pressing force of the grinding wheel on the raceway surface does not match in the forward path and the returning path. The difference between the pressing force in the forward path and the returning path, that is, the hysteresis phenomenon of the pressing force, differs according to the surface condition of the super-finishing grindstone.The more complete the sharpening, that is, the frictional resistance between the raceway surface The larger the value is, the larger the hysteresis appears, and the amount of hysteresis becomes small in the clogged state.
[0013]
The reason why the above phenomenon occurs can be assumed to be as follows.
Now, as shown in FIG. 6 (A), the grinding wheel to indicate orientation grindstone S is directed from one of the shoulder portions W _TS orbital plane W _T of the ball bearing on track center W _TC forward, in FIG. (B) S is the direction toward one shoulder W _TS from the track center W _TC Conversely the return path, as the pressing force of the grindstone S constant P, takes x and z directions as shown respectively, acting in the z-direction force Will be considered. In the forward path of FIG. 6 (A), the frictional force F between the grindstone S and the raceway surface W _T is the same direction shown in the orientation of the moving direction of the grinding wheel S. On the return path, the direction is reversed as shown in FIG.
[0014]
Force Pz in the z direction acting in the forward and backward at the same position of the track surface W _T 'is pressure P of the wheel S as described above is a Pz its z-direction component force the same, the frictional force F Assuming that the magnitude is the same and the z-direction component force is Fz,
Pz '= Pz + Fz (1)
On the return trip,
Pz '= Pz-Fz (2)
Thus, a difference is generated between the forward path and the return path according to the z-direction component of the frictional force F.
Then, the friction force F of the grinding wheel S and the raceway surface W _T is, the greater the good sharpness of the grinding wheel S, increases in other words as the dressing is complete, small at clogging state.
[0015]
Therefore, by detecting the pressing force of the super-finishing grindstone by the force detecting means via the shoe supporting the raceway, it is possible to know the dressing / clogging state of the grindstone. In addition, it is possible to determine the time point at which the processing is switched from the rough processing to the finishing processing and the time point at which the finishing processing ends. According to the method of determining the cycle of such roughing and finishing, the transition from roughing to finishing is performed according to the roughness of the raceway surface in the previous process and the progress of grinding wheel clogging in finishing. The time point and the end time point of the finishing process can always be kept constant. Therefore, it is possible to prevent the loss of required time and the shortening of the service life of the grindstone by making the rough machining longer than necessary, and also to prevent the accuracy of the raceway surface from being lowered by making the finish machining longer than necessary. .
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial cross-sectional view showing a mechanical configuration of a main part of an embodiment of the present invention, and FIG. 2 is a block diagram showing an electrical configuration of a main part of the embodiment.
[0017]
This example, there is shown a superfinishing apparatus for the outer ring of the ball bearing, the outer ring W _O of the ball bearing as the workpiece is formed with raceway surfaces W _OT annular its inner periphery, the raceway The surface _WOT is a target surface for the superfinishing.
[0018]
Outer ring W _O is the outer peripheral surface thereof is supported in the shoe 1, and one end face by a roller (not shown) is subjected to processing in a state of being pressed against the backing plate 2. The backing plate 2 is fixed to the tip of the main shaft 3. The main shaft 3 is rotated by driving a main shaft driving motor 25 (not shown in FIG. 1, see FIG. 2). W _O is given rotation.
[0019]
The super-finishing whetstone S is pressed downward by the whetstone pressing lever 5 while being held by the whetstone holder 4. The grindstone holder 4 is mounted on a superfinishing head (not shown) together with the grindstone pressing lever 5. The superfinishing head includes a pneumatic cylinder for pressing the superfinishing grindstone S downward through the pressing lever 5 and a swing drive mechanism motor 26 (not shown in FIG. 1; see FIG. 2). by the drive, and swing around the center of curvature of the raceway surface W _OT of the outer ring W _O, thereby superfinishing grindstone S swings while being pressed on the raceway surface W _OT.
[0020]
The shoe 1 is fixed to a shoe bracket 1a, and the shoe bracket 1a is attached to the device frame 6 so that one side of the shoe bracket 1a sandwiches the force sensor 7. In this structure, when pressed while swinging the superfinishing grindstone S with respect to the outer ring W _O, the pressing force the outer ring W _O, shoe 1 is transmitted further to the force sensor 7 through the shoes bracket 1a, therefore the force sensor the output of the 7 becomes proportional to the pressing force of the superfinishing grindstone S for the outer ring W _O.
[0021]
After the output of the force sensor 7 is amplified by the amplifier 21, high-frequency components and the like are removed by an appropriate low-pass filter 22, and the output is digitized by the AD converter 23 at minute intervals. The digitized force detection data is captured by the control device 24 every moment.
[0022]
The control device 24 is actually composed mainly of a CPU and its peripheral devices, a sequencer and the like, but in FIG. 2, for convenience of explanation, a block for each function of the control device 24 is shown. This is shown in the figure. In other words, force and hysteresis difference calculating unit 24a for calculating a difference delta of the forward path and the backward path of the pressing force at the grinding wheel oscillating end vicinity to be described later from the detection data, the value delta _R and is set in advance and the calculated difference delta a comparing unit 24b which compares the delta _F, includes a control unit 24c supplies a control signal to the respective units.
[0023]
The control unit 24c includes the main shaft drive motor 25, the swing drive motor 26, and the high / low pressure switching solenoid valve 27 for switching the air pressure to be supplied to the pneumatic cylinder of the super-finishing head to high / low pressure. You are under control. This control unit 24c, including loader for loading / unloading the outer ring W _O, although to control the entire apparatus, FIG. 2 shows only essential parts related to the present invention.
[0024]
Cycle of the entire superfinishing apparatus, in a state of being detached superfinished head from the state of FIG. 1, the outer ring W _O as the workpiece is loaded as shown in FIG. 1, and then rotates the spindle outer ring W After rotating _O to move the superfinishing head to the state shown in FIG. 1, the superfinishing grindstone S is _rocked while being pressed against the raceway surface _WOT , and the finishing is performed after the rough machining, and after the machining is completed. unloaded the outer ring W _O, loading the next of the outer ring W _O, it is a cycle of.
[0025]
Roughing rotates the outer ring W _O at a rotational speed R _R, while pressing the raceway surface W _OT a superfinishing grindstone S under a pressure F _R, be one that is swung by the swinging number O _R, finish in machining, the rotational speed higher _{R F} than _{R R,} lower _{P F} than the pressure _{P R,} the lower _{O F} than the swing speed _{O R.}
[0026]
The control device 24 determines the switching time point from the rough processing to the finishing processing and the ending time point of the finishing processing by using the instantaneous pressing force data taken from the force sensor 7 by the following method.
[0027]
When the super-finishing wheel S is in a dressing state, the output from the force sensor 7 is smoothed by the filter 22 and then enters a state illustrated in FIG. When in the clogged state, the state illustrated in FIG. That is, as described above, when performing superfinishing of the annular groove, such as the raceway surface W _OT of the outer ring W _O by superfinishing grindstone S, the pressing force by the grinding stone S, the shoe 1 through the outer ring W _O The transmitted component force in the direction in which the workpiece is supported causes a hysteresis phenomenon in which the pressing force differs between the forward movement and the backward movement in the vicinity of the swing end during one reciprocation of the swing, and the difference Δ in the pressing force during the reciprocation. (Hereinafter referred to as a hysteresis difference Δ) differs depending on the sharpness of the grindstone, that is, the dressing / clogging state.
[0028]
The hysteresis difference calculation unit 24a calculates a hysteresis difference Δ in the vicinity of a predetermined swing end for each swing of the grindstone S from the pressing force data from the force sensor 7, and for example, for each of the plurality of swings. Is calculated every moment and supplied to the comparison unit 24b. The comparison section 24b, at the time of roughing, when the value becomes larger until the magnitude delta _R set in advance, the grindstone S outputs the fact to the control section 24c as reached sharpening state. The control unit 24c, Beku migrate arrival time of the output from the rough processing after a certain time T _R which is set in advance has elapsed starting the finishing spindle drive motor 25, the swing drive motor 26, a high pressure / A control signal is supplied to the low pressure switching electromagnetic valve 27.
[0029]
Further, at the time of finishing, like hysteresis difference delta is at the time when decreased to size delta _F that is set in advance, as the grinding wheel has reached a clogging state, supplies the output to that effect to the control unit 24c I do. The control unit 24c supplies a control signal to the spindle drive motor 25, the swing drive motor 26, and the high-pressure / low-pressure switching electromagnetic valve 27 in order to stop the finishing processing when the output arrives.
[0030]
According to the above-described embodiment of the present invention, the value of the hysteresis difference Δ, in other words, the dressing state of the superfinishing grindstone S is as shown in the graph of FIG. 4 during one cycle of machining. That is, the grindstone S became clogged in the preceding outer ring W _O of the finishing step, will gradually dressed during roughing of the next outer ring W _O, eventually hysteresis difference pressure at the grinding wheel oscillating end vicinity Δ When There dressing is completed reaches the delta _R, that point reliably captured, the process proceeds to finishing at a certain time T _R has elapsed the dressing state, gradually clogging the grindstone S in its finishing and will, eventually hysteresis difference delta is when it becomes clogged equivalent reached delta _F is caught reliably terminates the finishing at that time.
[0031]
According to such processing, irrespective of the roughness of the raceway surface _WOT in the previous process, rough processing is performed for a fixed time by the grindstone S in a constant sharpening state, and a fixed clogging state of the grinding stone S. Finishing is performed until the time is reached, so that it is possible to eliminate waste of time and grindstone by spending more time than necessary for roughing, and deterioration of quality due to taking more time than necessary for finishing. .
[0032]
The position where the force sensor 7 is provided is not limited to the position described in the above embodiment, but any position may be used as long as the force acting on the shoe 1 in the supporting direction of the workpiece can be detected. Position.
[0033]
Further, in the above embodiment, an example in which the present invention is applied to the superfinishing device for the outer ring of the ball bearing is shown, but the present invention can be equally applied to the inner ring of the ball bearing. FIG. 5 shows an example of the configuration of the main part.
[0034]
Inner W _I of the ball bearing as the workpiece, the annular raceway surface W _IT are formed on the outer periphery, the raceway surface W _IT is processed surface superfinishing.
[0035]
The inner ring W _I, with its inner surface by the inner diameter shoe 11 which is fixed shoe body 11a is a rod-shaped surface is supported, pressed against the backing plate 12 by rollers (not shown), the distal end portion of the backing plate 12 by rotating the in which spindle 13 is fixed to the rotation is applied to the inner ring W _I. The super-finishing grindstone S is pressed downward by the pressing lever 15 while being held by the grindstone holder 14 in the same manner as in the above-described example, and by oscillating all of them, the superfinishing grindstone S becomes the inner race W while being pressed to swing against the raceway surface _{W IT} of _I.
[0036]
Two force sensors 17a and 17b are sandwiched between the lower surface of the support member 11b that cantileverly supports the inner diameter shoe 11 and the apparatus frame 16. These force sensors 17a, from the output of 17b, the pressing force against the raceway surface _{W IT} by superfinishing grindstone S is detected. From the detection output, the hysteresis difference Δ is obtained by a circuit configuration equivalent to that of the previous embodiment to determine the switching point from the roughing to the finishing, and the end point of the finishing. Equivalent effects can be obtained.
[0037]
【The invention's effect】
As described above, according to the present invention, a force sensor that detects a force acting on a shoe that supports a ball bearing raceway, which is a workpiece, is provided, and a superfinishing grindstone included in an output of the force sensor is provided. The clogging information is used to determine when to switch from roughing to finishing and when to finish finishing, so roughing and finishing depend on the condition of the raceway surface in the previous process and the condition of the grindstone surface at every moment. Optimum time is always spent, and compared to the conventional super-finishing machine that sets timers for roughing and finishing, respectively, the time and waste of grinding due to continuing roughing, and finishing more than necessary Deterioration in quality due to continuing processing can be prevented.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing a mechanical configuration of a main part of an embodiment in which the present invention is applied to a superfinishing device for an outer ring of a ball bearing.
FIG. 2 is a block diagram showing an electrical configuration of a main part of the embodiment of the present invention.
FIG. 3 is an explanatory diagram of an example of a detection result of a pressing force of the grindstone S by the force sensor 7 according to the embodiment of the present invention. FIG. 3 (A) shows a state where the grindstone S is in a dressing state, and FIG. It is a graph each showing the time when it is in the clogged state.
FIG. 4 is a graph showing a transition of a hysteresis difference Δ during one cycle of processing in the embodiment of the present invention.
FIG. 5 is a partial cross-sectional view showing a mechanical configuration of a main part of another embodiment in which the present invention is applied to a superfinishing device for an inner ring of a ball bearing.
FIG. 6 is an explanatory view of the reason why a difference occurs in the pressing force on the raceway surface between the forward path and the return path in the vicinity of the swing end of the superfinishing wheel.
[Explanation of symbols]
Reference Signs List 1 shoe 1a shoe bracket 2 backing plate 3 spindle 4 grindstone holder 5 pressure lever 6 device frame 7 force sensor 21 amplifier 22 low-pass filter 23 A / D converter 24 control device 24a hysteresis difference calculation unit 24b comparison unit 24c control unit 25 spindle Drive motor 26 Swing drive motor 27 High-voltage / low-pressure switching solenoid valve

Claims (2)

A device for super-finishing a raceway by pressing a super-finishing grindstone against a raceway surface while rotating the bearing ring of a ball bearing supported by a shoe. In the super-finishing device for raceway rings of ball bearings that perform roughing and finishing in order with
A force detecting means for detecting a force in the supporting direction acting on the shoe via the raceway during machining, and based on the force detection output, determines when to switch between the roughing and finishing and when to finish finishing. A super-finishing device for a bearing ring of a ball bearing, comprising a control means for determining. The control means switches from rough processing to finishing processing when the difference in force detection output during reciprocation of the grindstone near the swinging end of the grindstone increases and reaches a first value set in advance. 2. The ball bearing according to claim 1, wherein the ball bearing is operated such that a point when the second value smaller than the first value is reached is set as a reference point for finishing the finishing. 3. Super finishing device for raceway.

Images