Bore processing device

Abstract: A bore processing device for processing an inner surface of a bore of an object to be processed, includes: a taper member (3) having a taper section (3a); a roller (2) arranged to contact and rotate around an outer surface of the taper member; a roller guide member (1) having a guide groove (1a) for accommodating the roller and arranged to rotate around the outer surface of the taper member; a first motor (6) for moving the roller guide member to insert the roller into the bore of the object; a second motor (7) for rotating one of the object and the roller guide member; and a third motor (8) for axially moving one of the roller guide member and the taper member so that one of the roller guide member and the taper member relatively moves to the other thereof. The device further includes a detecting device (9) for detecting an axial load applied to the object by the roller when the roller is inserted into the bore of the object.

Description: The invention relates to a bore processing device for processing an inner surface of a bore of an object to be processed, comprising: a taper member having a taper section; rollers arranged to contact and rotate around an outer surface of the taper member; a roller guide member having a guide groove for accomodating the rollers and arranged to rotate around the outer surface of the taper member; a first motor for moving the roller guide member to insert the rollers into the bore of the object; a second motor for rotating the object and the roller guide member relatively to each other; a third motor for axially moving the roller guide member and the taper member relatively to each other to change the diameter of the circumscribed circle of the rollers; and a detecting means for detecting a load applied to the object by the rollers when the rollers are inserted into the bore of the object. EP-A-41 248 already shows such a bore processing device, in which the load detecting means measures the radial load, i.e. the rolling load. This measured value is used to manually adapt the rolling load to a predetermined value. The present invention specifically relates to a bore processing device for processing the bore of a high-accuracy bearing at high accuracy in cylindricity and surface roughness with plastic working, without a polishing process in which the bore is susceptible to flaws. Recently, high-accuracy bearings rotatable at high speed are used in business machines and consumer equipment and it is required to develop a hydrodynamic grooved bearing or a fluid bearing with higher accuracy. For the finishing process in the application of plastic working of the bearing bore, there are a known method, called as a pin sizing method, in which a pin is passed through the bore under pressure, and known method, called as a roller burnishing method (EP-A-41 248), in which a roller is passed rotating through the bore as shown in Figs. 5 to 7. Referring to the drawings, one example of the known methods will be described hereinbelow. Fig. 5 is a cross-sectional view of a conventional bearing processing device. Reference numeral 11 denotes a roller guide having a plurality of guide grooves 11a in which rollers 12 are rotatably accommodated. A processing tool 14 of the device is composed of the roller guide 11 and the rollers 12. Reference numeral 13 denotes a sleeve of the bearing as an object to be processed. The operation of the bearing bore processing device will be described hereinbelow. Firstly, the sleeve 13 is set on a working table (not shown) and thereafter the processing tool 14 is inserted downwardly into the bore of the sleeve 13 while rotating. At the time, since the processing tool 14 is designed to have a circle circumscribing the plural rollers 12 each of which diameters is greater few micron meters or ten micron meters than the inner diameter of the bore of the sleeve 13, the rollers 12 pass through the bore of the sleeve 13 under pressure while the processing tool 14 is rotating with the rollers 12, thus causing plastic deformation in the sleeve 13 and obtain the necessary inner diameter and surface roughness of the bore of the sleeve. However, the device has the following problems: in the plastic process, as shown in Fig. 7, it is easy to deform at both the ends of the bore of the sleeve. But the bore has a tendency in cylindricity δ to gradually protrude at the center thereof and form a curved shape in cross-section. Additionally, when there is a variation within 20 micron meters in the inner diameter of the sleeve bore before a plastic process, the bore has a variation within 10-15 micron meters in the inner diameter thereof after the plastic process. Therefore, in a fluid bearing having a sleeve, there is much radial run-out and a variation in performance under the quantity production. Accordingly, an essential object of the present invention is to provide a bore processing device capable of improving the accuracy of the inner diameter and cylindricity of a bore of an object to be processed. For accomplishing this object, a bore processing device as defined above is characterized in that the detecting means is an axial load measuring device detecting the axial load between the rollers and the object, to calculate the inner diameter of the bore of the object based on the detection; and that the diameter of the circumscribed circle of the rollers is adjusted on the basis of this calculation by moving the roller guide member relatively to the taper member by the third motor. By the above construction of the present invention, the inner diameter of the bore is detected by the detecting means and as a result of the detection, the circle can be adjusted in accordance with the detected value, resulting in less variation in the finished inner diameter of the bore. These and other objects and features of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings throughout which like parts are designated by like reference numerals, and in which: Fig. 1 is a cross-sectional view partially showing a bore processing device according to an embodiment of the present invention; Fig. 2 is a cross-sectional view taken in the line II-II of Fig. 1: Fig. 3 is a cross-sectional view showing a sleeve in the device; Fig. 4 is a cross-sectional view showing the whole construction of the bore processing device according to the embodiment of the present invention; Fig. 5 is a cross-sectional view partially showing a conventional bearing bore processing device; Fig. 6 is a cross-sectional view taken in the line VI-VI of Fig. 5: and Fig. 7 is a cross-sectional view showing a sleeve in the device. A bearing bore processing device according to one embodiment of the present invention will be described referring to Figs. 1 to 4. In Fig. 1, reference numeral 1 denotes a roller guide having a plurality of guide grooves 1a in which a roller 2 each rotatably inserted respectively. Reference numeral 3 denotes a taper pin having a taper section 3a at one end thereof. The rolled 2 moves around the axis of the taper pin 3 with the rotation of the roller guide 1 and the taper pin 3 is capable of moving in the directions shown by the arrows S and L with respect to the roller guide 1 therein so as to adjust the outer diameter of the taper pin 3, i.e. the diameter of the circle circumscribing the rollers 2. A processing tool 10 of the device is composed of the roller guide 1, the rollers 2, and the taper pin 3. Reference numeral 4 denotes a sleeve of a bearing as an object to be processed. In Fig. 4, reference numeral 5 denotes a base, reference numeral 6 denotes a first motor mounted on a support 5a of the base 5 and having a rod 6a with a feed screw, rotatably supported between the arms 5b of the support 5a, for engaging a slider section 1b of the roller guide 1. The first motor 6 rotates the rod 6a so as to move back and forth the taper pin 3 in the axial direction in the roller guide 1 and change the distance between the roller guide 1 and the sleeve 4, i.e. the diameter of the circle circumscribing the rollers 2. Reference numeral 7 denotes a second motor, mounted on the base 5, for rotating either the sleeve 4 or the guide 1. In this embodiment, the second motor 7 rotates the sleeve 4 through a chuck 7a connected to the second motor 7. The sleeve 4 is held by the chuck 7a. Reference numeral 8 denotes a third motor, mounted on the upper flange 1c of the roller guide 1, for moving the taper pin 3, and reference numeral 9 denotes a load sensor, mounted between the base 5 and the second motor 7, for detecting the axial load of the rollers 2 when the rollers 2 of the tool 10 are inserted in the bore of the sleeve 4 under pressure. According to the construction of the device, the operation thereof will be described hereinbelow. In Fig. 4, the sleeve 4 is rotated by the second motor 7 through the chuck 7a and the tool 10 is inserted in the bore of the sleeve 4 under pressure by the rotation of the first motor 6 so that the inner diameter of the bore of the sleeve 4 becomes larger. Thus, in this processing operation, the accuracy of the surface roughness thereof can be improved. In the processing operation, the taper pin 3 is moved with respect to the rollers 2 by the rotation of the third motor 8. Then, the diameter of the circumscribed circle of the rollers 2 is adjustable in the following way. That is, when the ends of the sleeve bore are processed, the diameter of the circumscribed circle becomes small, while when another portion except for the ends of the sleeve bore is processed, the diameter of the circumscribed circle becomes larger. Thus, as shown in Fig. 3, the sleeve 4 can be processed, with improved accurate cylindricity. In Fig. 4, the taper pin 3 is moved by the third motor 8 to set the diameter of the circumscribed circle of the rollers 2 to a specified value. In this condition, the tool 10 is inserted under pressure in the bore of the sleeve 4 by the first motor 6. The axial load in inserting the tool 10 into the sleeve 4 is detected by the load sensor 9 and the inner diameter of the bore of the sleeve 4 is calculated based on the detected value of the axial load. Then, the necessary plastic processing amount and the diameter of the circumscribed circle of the rollers 2 are determined in order to finish the inner diameter of the bore to a specified value. The rotation of the third motor 8 causes the diameter of the circumscribed circle of the rollers 2 to change, while the rotations of the first and second motors 6 and 7 cause the inner diameter of the sleeve 4 to be processed to a specified value with improved accurate cylindricity by the above processing operations. According to the embodiment, the inner diameter of the sleeve 4 and the cylindricity thereof can be accurately processed by changing the outer diameter of the tool 10. Instead of the rotation of the sleeve 4, the second motor 7 can rotate the roller guide 1.

Claims: A bore processing device for processing an inner surface of a bore of an object (4) to be processed, comprising: a taper member (3) having a taper section (3a); rollers (2) arranged to contact and rotate around an outer surface of the taper member; a roller guide member (1) having a guide groove (1a) for accomodating the rollers and arranged to rotate around the outer surface of the taper member; a first motor (6) for moving the roller guide member to insert the rollers into the bore of the object (4); a second motor (7) for rotating the object and the roller guide member relatively to each other; a third motor (8) for axially moving the roller guide member and the taper member relatively to each other to change the diameter of the circumscribed circle of the rollers (2); and a detecting means (9) for detecting a load applied to the object (4) by the rollers (2) when the rollers are inserted into the bore of the object; characterized in that the detecting means (9) is an axial load measuring device detecting the axial load between the rollers (2) and the object (4), to calculate the inner diameter of the bore of the object (4) based on the detection; and that the diameter of the circumscribed circle of the rollers (2) is adjusted on the basis of this calculation by moving the roller guide member (1) relatively to the taper member (3) by the third motor (8).

Inventors: ASADA TAKAFUMI, MORIMOTO MASATO, ASADA, TAKAFUMI, MORIMOTO, MASATO
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1991
Main classification: B24B39
IPC codes: B24B39, B21D3, F16C33