JP2002178244A - Grinding method for rolling element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding method for rolling elements capable of massively and highly precisely grinding the rolling surfaces of the multiple rolling elements at a low cost. SOLUTION: This grinding method of the rolling elements is characterized in that the same-size multiple unit balls are jointed with each other into an immobile state to form a virtual axis linearly penetrating through the centers of the respective unit balls, the rolling surfaces of the respective unit balls of the unit ball line are simultaneously ground by a centerless grinding device, and after the grinding, the unit ball line is taken apart into pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of grinding a rolling element, and more particularly to a method of grinding a rolling surface by a centerless grinding machine.

2. Description of the Related Art The present inventor has already filed an application for "Tamakoro" (trademark of Niken Sangyo Co., Ltd.)
-363197). "Ball roller" is a new rolling element having a large load capacity equivalent to "roller" and at the same time easy to handle as "ball", and includes a rolling bearing, a rolling linear motion guide device, a ball screw, Applicable to constant velocity joints and the like. This rolling element is based on the premise that it is manufactured at low cost and with high precision using commercially available elemental spheres. The end spherical surface is located on one virtual spherical surface, and the rolling spherical surface has an arc-shaped cross section. ing.

As a method for producing a large number of "ball rollers", the idea of using centerless grinding has been obtained. An object of the present invention is to provide a method for grinding a rolling element suitable for mass production of a new “ball roller”.

In order to achieve the above object, according to the present invention, a plurality of elemental balls having the same dimensions are joined to each other in an immovable state so as to extend straight through the center of each elemental ball. An axial center is formed, and the rolling surfaces of the element balls in the element ball array are simultaneously ground by a centerless grinder, and the element element rows are removed after the grinding. The joining of the elementary balls is based on electromagnetic attraction, and is characterized in that demagnetization is performed after grinding. Further, the joining of the elementary balls is performed by an adhesive, and the adhesive is removed after grinding. The rolling surface of the rolling element is ground in an arc shape in cross section, and a grinding groove having an arc cross section is formed at a predetermined pitch on a grinding wheel by a dresser.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 6 shows a "ball roller" as a rolling element to be ground by the grinding method of the present invention. The ball roller 1 has a rolling spherical surface portion 2 bulging in an arc shape, and spherical spherical surface portions 3 at both ends of the rolling spherical surface portion 2.
3, and the length W between the end surface spherical portions 3, 3 is longer than the maximum diameter d of the rolling spherical portion 2. The centers O of the left and right end spherical surfaces 3 and 3 are substantially equal, and substantially one virtual spherical surface B
The rolling spherical surface portion 2 is located above and has an arc shape having an arc radius larger than the radius of curvature of the end surface spherical portion 3, and this arc is located inside the virtual spherical surface B.
The rolling surface spherical portion 2 has the same diameter at both left and right ends, and has an arc shape symmetrical with respect to an axis passing through a center O orthogonal to the central axis X. The outer shape of the rolling element 1 is a shape obtained by combining the arc surface of the rolling spherical portion 2 and the spherical surfaces of the end surface spherical portions 3 and 3, and its longitudinal cross section has an intermediate shape between a substantially elliptical shape and a circular shape. The boundary between the rolling spherical surface portion 2 and the end spherical surface portions 3 and 3 is rounded. Assuming that the maximum diameter d of the rolling spherical portion 2 of the ball roller 1 is the short diameter and the length W between the end surface spherical portions (between the vertices) is the long diameter, the short diameter d is in the range of 80 ± 15% of the long diameter W. Preferably, it is set. 6 (A) to 6 (C)
6D is an example of 80%, and FIGS. 6D to 6F are examples of 90%. That is, the smaller the ratio between the minor axis d and the major axis W (the smaller the difference), the closer to a sphere, and the larger the ratio (the larger the difference).
As it approaches the roller, a high load capacity is obtained and it is suitable for heavy loads. Since the contact length of the rolling spherical surface portion 2 of such a ball roller 1 is longer than that of a ball, the load capacity is several times larger than that of the ball. Further, as shown in FIG. 6A, when the contact length is W1, the differential slip amount π (d−d0) due to the difference in diameter between the center and both ends is π (d−0) in the case of a ball. d1-
Since it is smaller than d0), the frictional resistance is reduced. Therefore, it moves lightly and generates a small amount of heat. In the case where the rotation axis of the rolling element 1 is greatly inclined with respect to the rotation axis of the bearing ring, as shown in FIG. Preferably has a tapered spherical shape. That is, the rolling spherical surface portion 2 has a large diameter at one end and a small diameter at the other end, and is inclined in a longitudinal arc. In the illustrated example, the ratio of the minor axis d to the major axis W is 8
This is an example of 0%. (Embodiment 1) Next, a method of grinding a "ball roller" according to Embodiment 1 of the present invention will be described with reference to FIGS. According to the present invention, as shown in the conceptual diagram of FIG. 1, a plurality of elementary balls 10 of the same size are joined to each other in an immovable state to form a virtual axis 11 that passes straight through the center of each elementary ball 10, The rolling is performed by simultaneously grinding the rolling surface 13 of each element ball 10 of the ball array 12 with a centerless grinding device, and removing the element ball array 12 after grinding. FIG. 2 shows a centerless grinding device used for this grinding. The centerless grinding device 20 includes a grinding wheel 21, an adjustment wheel 22 provided in parallel with the grinding wheel 21, for pressing a work on the grinding wheel 21 and rotating the work, and an arrangement wheel between the grinding wheel 21 and the adjustment wheel 22. A blade 23 is provided to support the lower surface of the work, and a joining jig 30 for joining the plurality of element balls 10 in an immobile state. The grinding wheel 21 is provided with a grinding groove 24 as shown in FIG. 1 for grinding the arc-shaped rolling surface 2 of the ball roller 1 at a pitch of the diameter D of the elementary ball 10. This grinding groove 24 has an arc shape corresponding to the arc shape of the final rolling surface of the "ball roller", and is shown in FIGS. 6 (A) and 6 (D).
As shown in FIG. 7, it is possible to easily grind a rolling surface in which the ratio of the short diameter d to the long diameter W is changed, and it is also possible to easily grind a tapered shape as shown in FIG. The adjusting wheel 22 is also provided with an arc-shaped engagement groove 25 that abuts on the element ball 10 corresponding to the grinding groove 24. However, a cylindrical surface may be used without providing the engagement groove 25. The adjusting wheel 22 is configured to advance and retreat toward the grinding wheel 21 by the feed mechanism 25. The elementary ball support surface of the blade 23 may be a flat surface or may be supported by a V-groove. Further, if an up-down movable mechanism for slightly moving the blade 23 up and down is provided so that the alignment is performed as the work becomes possible, the accuracy can be further improved.
In this embodiment, the joining jig 30 includes a plurality of element balls 10.
Are joined by electromagnetic attraction. This joining jig 30
A pair of magnetic pole pieces 31, 3 having opposite polarities are arranged above the elementary ball row 12 loaded between the grinding wheel 21 and the adjusting wheel 22.
1 and a body yoke 3 to which the pole pieces 31, 31 are attached
2, a magnetic force source (not shown), and a lifting device 34 for lifting and lowering the main body yoke 32. Fig. 1
An electromagnetic coil as shown in FIG.
The lifting device 34 includes a gripping position where the pole pieces 31, 31 grip both ends of the elementary ball row 12 in the axial direction, and a main body yoke 3.
2 is moved up and down between separated positions where the magnetic pole pieces 31, 31 are separated upward from the elementary ball row 12 by raising the magnetic pole pieces 2. The pole piece 31 is fixed to the body yoke 32 by a fixing screw 35.
, But is movable in the axial direction by a predetermined amount with respect to the main body yoke 32, so that the position of the pole piece 31 with respect to the elementary ball row 12 can be adjusted. The lifting device 34 includes a cylinder 36 as a driving source, and a cylinder 36.
Connecting shaft 37 connecting the main body yoke 32 and the connecting shaft 37
And a linear guide 38 for guiding the Next, with reference to FIG. 1 and FIG. 3, a description will be given of a process of grinding a ball using the centerless grinding device. First, the base ball 10 is prepared. As the base ball 10, a commercially available steel ball for a bearing is used. In particular, steel balls before quenching are used. The elementary spheres 10 are extremely high in roundness and dimensional accuracy on the order of submicron, and the relative difference between the individual elemental spheres 10 is very small and extremely uniform. The point is to use this homogeneous elementary sphere. The use of such a homogeneous elementary ball has the advantage that the dimensional accuracy of the product after grinding is constant and that grinding can be performed with extremely high precision. A predetermined number of the elementary balls 10 are supplied to the centerless grinding device 20. Each element ball 10 is a grinding wheel 21
Into the space between the grinding groove 24 and the engaging groove 25 of the adjusting grindstone 22, and is set on the blade 23. Next, the cylinder 36 of the electromagnetic joining jig 30 is driven to drive the main body yoke 3.
2 is lowered toward the elementary ball row 12. The position of the magnetic pole piece 31 is adjusted in advance to both end positions of the elementary ball row 12, and the magnetic pole piece 31 is positioned so as to sandwich both ends of the elementary ball row 12 from above.
2 are inserted at both ends. At this time, it is preferable that the magnetic pole piece 31 is pressed by a spring or the like so as to surely contact the element balls 10 at both ends of the element ball row 12. Next, the electromagnetic coil 33 of a magnetic force source (not shown) is excited. Then, a magnetic path H passing through the main body yoke 12, the pole piece 31 and the elementary ball row 12 is formed, and the elementary balls 10 are joined to each other immovably by magnetic attraction. Each elementary sphere 10 is linearly arranged along the line of magnetic force passing through the center of each sphere, and forms an imaginary axis center linearly penetrating the center of each elementary sphere (see FIGS. 1 and 3). Since the contact point of each element ball 10 is a point contact, the magnetic flux is concentrated at each contact point and the magnetic flux density is concentrated, and the magnetic attraction force between each element ball is high, so that the contact point does not move. Then, the adjusting wheel 22 is pressed toward the grinding wheel 21 and the grinding wheel 21 is pressed.
And grinding is performed by rotating the adjusting wheel 22. At the time of this grinding, the element ball row 12 is rotated by the frictional force with the adjusting wheel 22, and the contact between the element ball 10 at both ends and the contact point of the pole piece 31 is rotated and slid. Since it is small, it rotates smoothly without hindering the rotation of the elementary ball row 12. Further, since the rotation axis of the elementary ball row 12 is lowered by the grinding allowance, it is preferable to move the blade 23 up and down to absorb the grinding allowance. After the grinding is completed, a current having a polarity opposite to that at the time of the attraction is applied to the electromagnetic coil 33 to demagnetize the residual magnetism remaining in the elementary ball array 12 and take out the ground elementary ball. Thereafter, post-processing such as heat treatment is performed on the ground elemental ball as necessary, to complete the “ball roller”. When the grinding surface is worn, the grinding groove 24 of the grinding wheel 21 is dressed by a rotary dresser (not shown). As in the present invention, contacting the elementary balls with extremely high dimensional accuracy means that they correspond exactly to the groove pitch of the grinding groove, and the grinding position by the rotary dresser can also correspond exactly,
As a result, an accurate “ball roller” can be ground.
In addition, when the element balls 10 are brought into contact with each other for grinding, the number of pieces that can be ground in a single grinding can be increased, and a larger amount can be processed. Second Embodiment Next, a second embodiment of the present invention will be described. In the following description, only different points from the first embodiment will be described, and the same components will be denoted by the same reference numerals and description thereof will be omitted. 4 and 5 show an example in which an adhesive is used as a method for joining a plurality of elementary balls in an immobile state. That is, as shown in FIG. 4, a plurality of element balls 10 supplied to the centerless grinding device are provided.
The two are fixedly joined to each other by an instant adhesive 51 to perform centerless grinding. FIG. 5 shows an instant adhesive 5
Bonding jig 4 for spraying or dripping 1
0 is shown. The bonding jig 40 is disposed above the elementary ball row 12 loaded between the grinding wheel 21 and the adjustment wheel 22.
A plurality of nozzles 41 for spraying or dropping the instant adhesive 51, a support bar 42 for supporting the nozzles 41, and element balls provided on the support bar 42 and located at ends of element element rows And an abutting piece 43 for abutting the element bar to position the elementary ball row in the axial direction, and an elevating device 44 for elevating and lowering the support bar 42. The elevating device 44 includes a cylinder 46 as a drive source, a connection shaft 47 connecting the cylinder 46 and the support bar 42, and a linear guide 48 for guiding the connection shaft 47. Next, a grinding process using the bonding jig 40 will be described. The cylinder enters the space between the grinding groove 24 of the grinding wheel 21 and the engagement groove 25 of the adjusting grindstone 22, and drives the cylinder 46 of the bonding jig 40 to support the elementary ball row 12 set on the blade 23. Bar 4
2 is lowered toward the elementary ball row 12. The position of the contact side 41 is adjusted in advance to one end position of the element ball array 12, and the element ball array 12 is sandwiched from both ends with a positioning piece 50 provided on the blade 23, and a gap is provided between the element balls. Make sure there is no contact. Also in this case, it is preferable that the contact piece 41 is pressed by a spring or the like so as to securely contact the elementary ball row 12. When the axial position of the element ball array is determined in this way, the contact position of each element ball matches the nozzle position of the instant adhesive (see FIGS. 4 and 5). Next, the instant adhesive 51 is sprayed or dropped from the nozzle 41 around the contact points of the element balls 10, and the element balls 10 are immovably joined to each other by the adhesive force of the instant adhesive 51. As a result, the elementary spheres 10 are arranged on a straight line passing through the center of each sphere, and an imaginary axis O passing straight through the center of each elementary sphere is formed. In some cases, before setting in this centerless grinding device, the elementary balls are brought into contact with each other with a jig having a V-groove and arranged in a straight line, and after forming a rod-shaped elementary ball row in advance, the centerless grinding device is used. It may be set. Then, the grinding wheel 21 and the adjustment wheel 22 are rotated to perform the grinding. The element ball array 12 is rotated by the frictional force with the adjusting wheel 22, and the element balls 10 at both ends, the contact piece 41 and the positioning piece 5
Although the point of contact with 0 rotates and slides, it is a point contact and the friction torque is small, so that it rotates smoothly without hindering the rotation of the elementary ball row 12. In addition, the element ball row 12 is displaced in a direction orthogonal to the rotation axis by an amount corresponding to the grinding allowance,
The contact between the contact piece 41 and the positioning piece 50 slides to absorb the displacement. After the grinding is completed, the element balls are taken out, and the adhesive between the element balls is removed by a chemical or the like, so that the element balls 10 are separated. Thereafter, post-processing such as heat treatment is performed on the ground elemental ball as necessary, to complete the “ball roller”. In each of the above embodiments, the case where the “ball roller” is ground as the rolling element has been described. However, the rolling surface may be a cylindrical surface instead of an arc-shaped bulging shape, or may be concavely concave. Grinding can also be performed on shapes.

As described above, according to the present invention,
By contacting and grinding elemental balls having high dimensional accuracy, uniform rolling elements can be mass-produced at low cost.
In particular, since each elemental ball is joined and ground, a grinding wheel can be effectively used, and a larger amount of elementary balls can be ground. In addition, since the elementary balls are arranged with a pitch having a diameter with high dimensional accuracy, it is possible to accurately correspond the positions of the grinding grooves of the grinding wheel and the teeth of the dresser for dressing the grinding grooves.

[Brief description of the drawings]

FIG. 1A is a conceptual diagram of a rolling element grinding method according to Embodiment 1 of the present invention, and FIG. 1B is a diagram showing a state where the elementary sphere of FIG. 1A is ground. is there.

FIG. 2 is a schematic view of a centerless grinding apparatus to which the method for grinding a rolling element according to the present invention is applied.

3 (A) is a front view showing the configuration of the joining jig of FIG. 2, and FIG. 3 (B) is a side view of a main part of FIG. 3 (A).

FIG. 4 (A) is a conceptual diagram of a rolling element grinding method according to Embodiment 2 of the present invention, and FIG. 4 (B) is a diagram showing a state where the elementary sphere of FIG. 4 (A) is ground. is there.

FIG. 5 is a view showing an adhesive jig used in the grinding method according to the second embodiment.

FIG. 6 shows a rolling element ground by the grinding method of the present invention. FIGS. 6A, 6B, and 6C show a ratio of the minor axis to the major axis of 80%, and FIG. D), (E),
(F) is a front view, a plan view, and a side view of a rolling element of 90%, respectively.

FIGS. 7A and 7B show a rolling element in which a rolling spherical surface portion has a tapered shape. FIG. 7A is a front view, and FIG. 7B is a side view.

[Explanation of symbols]

Reference Signs List 10 elementary ball, 11 virtual axis center, 12 elementary ball row, 20 centerless grinding device, 21 grinding wheel, 22 adjusting wheel, 23
Blade, 24 grinding groove, 30 joining jig, 31 magnetic pole piece, 32 main body yoke, 33 magnetic force source 40 bonding jig, 41 nozzle, 42 support bar, 43
Contact piece 50 Positioning piece, 51 Instant adhesive.

Claims (4)

[Claims] A plurality of elemental balls having the same dimensions are joined to each other in an immovable state to form an imaginary axis that linearly penetrates the center of each elemental ball, and a rolling surface of each elemental ball in the elementary ball row is formed. A grinding method for rolling elements, characterized in that simultaneous grinding is performed by a centerless grinding machine, and a row of element balls is released after grinding. 2. The method for grinding rolling elements according to claim 1, wherein the element balls are joined by electromagnetic attraction, and demagnetized after grinding. 3. The bonding between elementary balls is performed by an adhesive,
The method for grinding a rolling element according to claim 1, wherein the adhesive is removed after grinding. 4. The rolling surface of a rolling element is ground into an arcuate cross section, and a grinding wheel is formed with a grinding groove having an arcuate cross section at a predetermined pitch by a dresser on a grinding wheel. The method for grinding a rolling element according to any one of the above items.