JP2552374B2 - Chamfer grinding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a chamfer at an edge portion between a groove and an outer peripheral surface of a component in which the outer peripheral surface is circular and grooves are formed at predetermined intervals in the circumferential direction. The present invention relates to a chamfer grinding method for grinding a surface, and particularly to a method for grinding a chamfer on an edge portion of a valve shaft of a power steering.

(Prior Art) FIGS. 6 (A) and 6 (B) are views showing an example of the power steering, in which the pinion 11 is provided in the front housing 10a.
Is rotatably mounted, and the pinion 11 meshes with a rack 12 connected to wheels (not shown). A hollow valve body 13 is housed in a rear housing 10b that is integral with the front housing 10a and constitutes the housing 10. The valve body 13 is connected to the pinion 11 by a pin 14.

The tip end of a torsion bar 15 is press-fitted into the rear end of the pinion 11 so as to be integrated, and a valve shaft is provided between the torsion bar 15 and the valve body 13.
16 built in. The valve shaft 16 has its rear end fixed to the rear end of the torsion bar 15 by a pin 17. As shown in FIG. 6 (A), the torsion bar 15 is connected to a steering wheel 18, and the steering rotation of the wheel 18 causes the rack 12 to axially move through the torsion bar 15 and the pinion 11. Since the vehicle slides on the wheel, the wheels are steered.

In order to assist the steering force applied to the steering wheel 18, the pressure oil discharge portion 21 of the hydraulic pump 20 driven by the engine is provided in the inflow port 2 formed in the rear housing 10b.
Connected to two. As shown in FIG. 6 (A), the inflow port 22 communicates with an annular groove 23 formed in the valve body 13, and the annular groove 23 has three inflow sides formed in the valve body 13. Via the communication hole 24 and the three outflow-side communication holes 25 formed in the valve shaft 16,
It communicates with the oil chamber 26 in the valve shaft 16. An outlet port 27 is formed in the rear housing 10b, and the oil chamber 26
The pressure oil inside is the other communication hole 28 formed in the valve shaft 16.
And returns to the tank 29 via the outflow port 27.

As shown in FIG. 6 (B), the outflow side communication hole 25 is continuous with the secondary valve port groove 32, and these secondary valve port grooves 32 are 120 ° with respect to each other about the axis. The phases are out of phase, and the primary valve port groove 31 is formed in the valve shaft 16 by shifting the phase by 60 ° with respect to these secondary valve port grooves 32. Six spool portions 33 are formed between the valve port grooves 31, 32 in the circumferential direction. In the valve body 13, right cutting land portions 34a and left cutting land portions 34b are alternately formed in the circumferential direction. The right cutting land portion 34a is connected to the right port 37a of the power cylinder 37 by the oil passage 35, and the left cutting land portion 34b is connected.
Is connected to the left port 37b of the power cylinder 37 by an oil passage 36. A piston 38 integrated with the rack 12 is provided in the power cylinder 37. In FIG. 6 (B), reference numeral 39 is the rack 12
Shows a tire connected to.

FIG. 6 (B) shows the relative positions in the rotational direction of the valve shaft 16 and the valve body 13 when the vehicle is set to the straight running state. At this time, the circumferential end portions of the respective spool portions 33 are shown. The pressure oil from the pump 20 returns to the tank 29 through the throttle portion 40 formed by the land portion 34a, 34b and the land portion 34a, 34b, the pressure oil does not become congested inside, the power cylinder 37 is operated. do not do.

Then, for example, the steering wheel (handle)
Assuming that the steering wheel 18 is rotated to the left, the rotation causes the tonton bar 15 to rotate to the left to move the rack 12 axially via the pinion 11 as well as to rotate the torsion bar 15
Since the valve shaft is twisted, the valve shaft 16
It rotates relative to 13 to the left. As a result, pressure oil is congested in the valve, and the left port 37
As a result, the steering force is assisted by the power cylinder 37.

(Problems to be Solved by the Invention) FIG. 6 (C) is a view showing a part of the valve shaft 16 shown in FIG. 6 (B). In this figure, the respective valve port grooves 31 described above are shown. , 32 of them are designated by the reference numeral 41. As shown in this figure, a chamfer G is formed at an edge portion E formed by the end surface F of the groove 41 and the outer peripheral surface of the valve shaft 16. This chamfer G is ground to a predetermined step size S by grinding, and its accuracy is required to be as high as ± 0.003 mm. The reason is that the chamfer G forms the throttle portion 40 shown in FIG. 6 (B). If the throttle portion 40 does not have a predetermined accuracy, the steering wheel 18 is moved in the left-right direction. This is because the steering torque is different in the left-right direction when the steering is turned, that is, when the steering wheel is turned left and right.

This chamfer G is ground by cutting a predetermined number of valve shafts 16, for example, six valve port grooves as shown in FIG.
Regarding the edge portion E in FIG.
Grinding is performed on the points.

Various processing methods have been attempted for this grinding process, but it has been difficult to perform the processing with high accuracy and high efficiency. For example, after chamfering two adjacent edge portions on both end faces F of one valve port groove with a grinding wheel, it is measured whether or not a predetermined dimension S is obtained, and the valve shaft 16 is indexed and rotated. Attempts have been made to position other valve port grooves.
However, in this method, not only the positioning accuracy of the center position of the valve port groove is not good, the machining efficiency is not good, but also a step may occur between the adjacent chamfer parts.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to enable grinding of a chamfer with high accuracy and efficiency.

(Means for Solving the Problems) The present invention for achieving the above-mentioned object has a circular outer peripheral surface, and among the workpieces having a plurality of grooves formed at predetermined intervals in the circumferential direction, A chamfer grinding method for grinding a chamfer on an edge portion formed by the groove and the outer peripheral surface, wherein a center position of any one of the plurality of grooves is set for each workpiece to be ground. Storing its center position data by measuring with a detector, storing data of all indexed positions of the edge portion with the center position as a reference, and grinding any one of the edge portions with a grinding wheel, The step difference of the chamfer after grinding is detected by the detector, and the moving distance of the grindstone that becomes the predetermined step is stored, and by the indexing position and the moving distance of the grindstone that are already stored respectively, all other Grinding the edge part of It is a chamfer grinding method characterized by being processed.

(Function) Among the plurality of grooves for each workpiece to be ground,
The center position of any one groove is first determined by the detector. Using this center position as a reference, the edges of all grooves including this groove and the outer peripheral surface of the work, that is, the position of the part to be ground is determined by the detector by rotating the work. To be And either one
The chamfer surface is machined with a grinding wheel for the part of the one groove to be machined. At this time, the step difference on the chamfered surface after grinding is calculated by the detector, and whether or not the step difference value is a predetermined value is calculated. If it is a predetermined value, the value is stored. To do. Further, all the other chamfer surfaces are processed based on the stored data of the position to be processed and the data of the step difference.

(Example) Next, the present invention will be described in detail based on an illustrated example.

FIG. 1 is a view showing a schematic structure of a grinding device embodying the grinding direction of the present invention, that is, a valve shaft 16 which is a work.
Is gripped at one end by a chuck 51 provided on the spindle head 50, and is rotated in the Y-axis direction by a servo motor 52 provided on the spindle head 50. Valve shaft
The other end of 16 is rotatably supported by the center 53. A grinder 55 having a grindstone 54 located above the valve shaft 16 is provided so as to be movable in the vertical direction, that is, the Z-axis direction.
It is designed to be performed by the servo motor 56.

A detector 57 having a contactor adjacent to and in contact with the work 16 is provided. The detector 57 is operated via a detection circuit 59 in response to a signal from an arithmetic processing unit CPU 58 including a microcomputer. The operation of each of the servomotors 52 and 56 is controlled by a control signal from the CPU 58 via the motor drivers 60 and 61.

A procedure for processing the valve shaft, that is, the work 16 according to the grinding direction of the present invention using such a grinding device will be described with reference to the flowchart shown in FIG.
The shape of the work 16 is the same as that described above, and the shape is shown in FIG. In this figure, for the chamfer to be processed, for one valve port groove 41, the portion located on the right side is indicated by the reference symbol R, and the left side portion is indicated by the reference symbol L.

First, with respect to the grinding machine shown in FIG. 1, a valve shaft 16 having six valve port grooves 41 pre-cut as shown in FIG. 3 is held by a chuck 51 and supported by a center 53. To do. At this time, the center of any one of the six valve port grooves 41 is positioned at the detector 57,
The valve shaft 16 is mounted without making the accuracy so high. In this way, when it is determined in step 70 that the work 16 has been mounted, the position of the groove 41 is measured by the detector 57 in step 71 for the groove at the position substantially corresponding to the detector 57. .

The procedure for detecting the groove position is shown in FIG.
The tip of the detector 57 is inserted into the groove 41, and is horizontally moved in the X-axis direction until the tip of the detector 57 contacts both end faces F. As a result, the CPU 58 calculates the center position of the groove from the movement amount of the detector. As a result, the center position of one of the six grooves is obtained. Since the center positions of the grooves in the circumferential direction are formed with a predetermined accuracy, the center position of one groove is determined. If is determined, the center positions of the other grooves are not measured.

From this state, after moving the detector 57 to a predetermined detecting position, the work 16 is rotated in the Y-axis direction by the servo motor 52 in step 72, and the distance from the groove center to the position of R1 is detected in step 73. It is measured by 57 and the value is stored in the storage medium in the CPU 58. Similarly, the Y-axis rotation and the measurement of each processing portion are performed at a total of 12 points up to L6. The measurement of the twelfth distance and the storage of the value are ended in step 76.

In this way, after the position data of each processed portion is stored, the grinding processing of each portion is performed. First, in step 77, the Y-axis is indexed and rotated based on the stored data, and the first processing portion R1 is processed by the grinding wheel 54. When this processing is completed, the processing amount of the processed chamfer, that is, the step S is measured using the detector 57, and if the step is less than the set amount, reprocessing is executed in step 79. In addition, if more than the set amount has been processed, it cannot be repaired, so the device is stopped and the work is discarded. After reworking in step 79, the amount of the step S is measured again in step 80 using the detector 57, and the same processing as described above is performed. When the amount of the step S is smaller than the set value, this reworking is repeated a predetermined number of times.

If it is determined in step 78 or 80 that the step has reached the set value, the positioning movement distance of the grindstone 54 in the Z-axis direction by the servo motor 56 required to obtain this step is stored in the storage medium. It Therefore, at the time of subsequent processing, the amount of step difference is set by the stored movement distance data. In this way, after the R1 portion is processed, the work 16 is rotated in the Y-axis direction by the Y-axis direction indexing angle that was already stored in step 82 in order to position the grindstone 54 at the L1 portion, and further, Grinding of L1 is performed by moving the grindstone 54 in the Z-axis direction so that the amount of the step difference is already stored. After the processing in step 82 is completed, Y-axis indexing is performed to machine the R2 portion. Also at this time, a desired step can be obtained by moving the grindstone 54 in the Z-axis direction by the stored distance without measuring the step as in the processing of L1. This is performed for the remaining processing parts in the same procedure, and if it is determined in step 84 that the processing of all 12 positions has been completed, the processing ends.

According to the present invention, in order to chamfer the edge portion formed by the groove and the outer peripheral surface of a work such as a valve shaft having a circular outer peripheral surface and having a plurality of grooves formed in the circumferential direction. The center portion of any one of the grooves is obtained using the detector, and the workpiece is sequentially rotated to measure the portion to be processed by the detector, and the distance data is stored in the storage medium. In addition, processing one processing part,
The detector detects whether or not the step of the chamfer has a predetermined value, and an appropriate amount of the step, that is, the moving stroke of the grinding wheel is stored. Then, the subsequent chamfer unit calls the stored Y-axis indexing distance and the moving stroke of the grindstone to perform processing.

FIG. 5 is a diagram showing the details of the grinding device shown in FIG. 1, in which the grinder 55 is slidable in the vertical direction, that is, in the Z-axis direction on the column 63. 55 also slides in the direction perpendicular to the paper surface. Although the center 53 is shown in FIG. 5, the bolster part 65 supporting the pedestal part 64 having this center 53 moves in the horizontal direction, that is, the X-axis direction together with the spindle head 50 shown in FIG. It is free. As a result, the relative position of the grindstone 54 and the workpiece in the X-axis direction is set.

The detector 57 is provided at the tip of a sliding beam 66 which is movable on the support column 63 in the X-axis direction, and the detector 57 also slides in the vertical direction.

In addition to the valve shaft having the six valve port grooves as described above, the work to be machined may have various numbers of grooves and various uses of the work.

(Effect of the Invention) As described above, according to the present invention, the center position of any one of the plurality of grooves is determined by the detector for each workpiece to be ground, and the workpiece is referenced based on that position. Since the position in the rotation direction is set, the work positioning accuracy is improved. Further, the center positions of the other grooves are also estimated based on the already-obtained center positions, and all the grooves can be processed quickly. Furthermore, before grinding, the positions of all the parts to be processed are detected and stored, and as a result of the stored data, the work is indexed and rotated.
Since it is not necessary to alternately perform the detection of the indexing position and the grinding process, the machining efficiency is greatly improved. The step size of the chamfer surface is determined by measuring the step size with a detector when the first part is processed in consideration of the wear of the grindstone. It has become possible to machine the chamfered surface with an accurate step size.

As described above, the chamfer grinding process can be performed with high accuracy and high efficiency on the edge portion formed by the groove and the outer peripheral surface, which are already formed on the work in accordance with the individual work.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a grinding apparatus embodying the chamfer grinding method of the present invention, FIG. 2 is a flow chart showing the grinding process of the present invention, and FIG. 3 is a sectional view showing details of a work. Fig. 4 is an enlarged sectional view showing a part of the work shown in Fig. 3, Fig. 5 is a front view showing a part of the grinding device shown in Fig. 1, and Fig. 6 (A). Is a sectional view showing the details of the power step ring in which the valve shaft as a work is incorporated, and FIG. 6 (B) is the same figure (A).
FIG. 6C is an enlarged sectional view showing a chamfer surface formed on the work, taken along line BB in FIG. 16 ... Valve shaft, 41 ... Valve port groove, R1 to R6 ... Edge part, L1 to L6 ... Edge part, 54 ... Grinding wheel, 57 ... Detector, 58
…CPU.

Claims (1)

(57) [Claims] 1. A workpiece having a circular outer peripheral surface and having a plurality of grooves formed at predetermined intervals in the circumferential direction, a chamfer is provided at an edge portion formed by the groove and the outer peripheral surface. A chamfer grinding method for grinding, wherein a center position of any one of the plurality of grooves is measured by a detector for each workpiece to be ground, and the center position data is stored. All the indexed positions of the edge portion are measured with a detector with the center position as a reference, and the data is stored,
After grinding any one of the edge portions with a grinding stone, the step difference of the chamfer after grinding is detected by the detector, and the moving distance of the grindstone that becomes a predetermined step is stored, and each is already stored. A chamfer grinding method characterized in that all the other edge portions are sequentially ground according to the indexing position and the moving distance of the grindstone.