Honing machine and honing method

Abstract

To machine at least one portion in a circumferential direction of an inner surface having a circular cross section of a workpiece so as to be recessed more than the other portion with high accuracy in a small number of processes by honing.SOLUTION: A honing method uses a honing machine 1 that includes: a rotatable tool shaft 2; a plurality of grinding stones 4 arranged on the tool shaft 2 so as to advance and retreat in a radial direction and rotating integrally with the tool shaft 2; tapered cones 7 connected to the tool shaft 2 and vertically moving to advance and retreat the plurality of grinding stones 4 in the radial direction; and a tapered cone drive part vertically driving the tapered cones 7. The honing method comprises: creating a timing chart so as to vertically move the tapered cones 7 in accordance with a recess of the inner surface of the circular cross section; and controlling the drive part of the tapered cones 7 in accordance with the timing chart to vertically move the tapered cones 7 while expanding or contracting a diameter of the plurality of grinding stones 4, thereby grinding the inner surface of the circular cross section.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a honing machine and a honing method for processing at least a part of the circumferential direction of the inner surface of a circular cross-section in a workpiece to be recessed more than other parts.

Background Art

[0002] Conventionally, as shown in FIG. 13, a hydrodynamic bearing 50' has a structure in which the rotation shaft 53' is rotated by the pressure of an oil film fluctuating (a high-pressure portion 52' is formed) during rotation. In order to vary the pressure of the oil film, an oil film pocket 51' is provided on the bearing side. In order to grind this oil film pocket 51', as shown in FIG. 14, after machining a perfect circle hole A centered on the center point O, three holes B having an inner diameter smaller than that of the hole A are machined at three positions centered on the eccentric point O' using a jig (not shown). By machining each of these holes B, three oil film pockets 51' are formed.

[0003] For example, as in Patent Document 1, when honing the non-circular inner peripheral surface of a cylinder bore with a honing head, the honing head is rotated around the rotation axis center and moved along the inner peripheral surface of the cylinder bore while grinding the inner peripheral surface of the cylinder bore with three grinding stones.

[0004] Also, in the case of Patent Document 2, when grinding the inner peripheral surface of a cylinder with a grinding stone, an oil supply device applies a constant pressure to the oil, and the oil in the hydraulic chamber pushes the piston in the expanding diameter direction. As a result, the tip of the piston contacts the inner surface of the shoe, and the shoe to which the grinding stone is fixed is pushed out in the expanding diameter direction. On the other hand, when finishing the grinding of the inner peripheral surface of the cylinder, the pressure applied by the oil supply device to the oil is reduced. As a result, the contracting force of the return spring moves the shoe to which the grinding stone is fixed in the contracting diameter direction. Thereby, when there are irregularities along the vertical direction on the inner peripheral surface of the workpiece, that is, when the inner diameter of the inner peripheral surface changes along the vertical direction, the grinding stone can follow the change in the shape of the inner peripheral surface to prevent over-grinding.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in conventional honing machines, a dedicated eccentric jig is required, and since machining is performed in multiple steps through setup, extra time is required for machining. In addition, since true circles at multiple eccentric points cannot be machined simultaneously, it is difficult to control the wear of the grinding stone, and there is a problem that it is difficult to machine a uniform shape.

[0007] Further, both Patent Documents 1 and 2 are for inner surface finishing while maintaining an existing uneven shape, and are not technologies for forming a non-circular shape with an oil film pocket from a circular hole portion by a honing tool.

[0008] The present invention has been made in view of such points, and an object thereof is to perform honing machining to machine at least a part of the circumferential direction of the cross-sectional circular inner surface of a workpiece to be recessed more than other parts with high accuracy in fewer steps.

Means for Solving the Problems

[0009] In order to achieve the above object, in this invention, a plurality of grinding stones can be expanded or contracted in diameter in accordance with the unevenness of the inner surface of the workpiece during honing machining.

[0010] Specifically, in the first invention, targeting a honing machine for machining at least a part of the circumferential direction of the cross-sectional circular inner surface of a workpiece to be recessed more than other parts, The honing machine is a rotatable tool shaft, a plurality of grinding wheels arranged on the tool shaft so as to be movable forward and backward in the radial direction and rotating integrally with the tool shaft, a tapered cone drive shaft provided inside the tool shaft and moving up and down, a tapered cone provided at the lower end of the tapered cone drive shaft and moving up and down to move the plurality of grinding wheels forward and backward in the radial direction, and a tapered cone drive unit that moves the tapered cone up and down in accordance with the recess in the circular cross-sectional inner surface to expand or contract the plurality of grinding wheels.

[0011] According to the above configuration, the control unit controls the tapered cone drive unit to move the tapered cone up and down in accordance with the recess in the circular cross-sectional inner surface to expand or contract the plurality of grinding wheels, so that at least a part of the circumferential direction of the circular cross-sectional inner surface of the workpiece can be processed to be recessed more than other parts without tool change.

[0012] In the second invention, targeting a honing machine for processing at least a part of the circumferential direction of the circular cross-sectional inner surface of a workpiece to be recessed more than other parts, the honing machine is a rotatable tool shaft, a plurality of grinding wheels arranged on the tool shaft so as to be movable forward and backward in the radial direction and rotating integrally with the tool shaft, a tapered cone drive shaft provided inside the tool shaft and moving up and down, a tapered cone provided at the lower end of the tapered cone drive shaft and moving up and down to move the plurality of grinding wheels forward and backward in the radial direction, a ring member provided on the tapered cone and having unevenness formed at intervals in the circumferential direction so as to move the tapered cone up and down in accordance with the recess in the circular cross-sectional inner surface, and a cam follower provided on the tapered cone and contacting while relatively rotating with respect to the ring member and moving relatively up and down in accordance with the unevenness of the ring member to move the tapered cone up and down.

[0013] According to the above configuration, when the tool shaft is rotated, the cam follower relatively rotates in a state of being in contact with the ring member, and relatively moves up and down in accordance with the unevenness of the ring member, thereby moving the tapered cone up and down to expand or contract the diameters of a plurality of grinding wheels. Thereby, without changing the setup, it is possible to machine at least a part of the circumferential direction of the inner surface of the cross-sectional circle in the workpiece to be recessed more than other parts.

[0014] In the third invention, in the second invention, a bulging portion is formed on the ring member in accordance with the recess in the inner surface of the workpiece, and the cam follower is composed of a roller that can ride on the bulging portion.

[0015] According to the above configuration, while the cam follower and the ring member relatively rotate, the roller-shaped cam follower rides on the bulging portion of the ring member and relatively moves in the vertical direction to move the tapered cone, and by expanding the diameters of a plurality of grinding wheels, without changing the setup, it is possible to machine at least a part of the circumferential direction of the inner surface of the cross-sectional circle in the workpiece to be recessed more than other parts.

[0016] In the fourth invention, in the third invention, the bulging portion of the ring member is configured to be height-adjustable.

[0017] According to the above configuration, by adjusting the height of the bulging portion of the ring member, the moving amount of the cam follower can be adjusted to adjust the expanding amount of the diameters of a plurality of grinding wheels, so that the size of the recess can be appropriately and easily determined.

[0018] In the fifth invention, in the fourth invention, an adjustment screw is provided on the ring member so that the height of the bulging portion can be adjusted by rotation.

[0019] According to the above configuration, by adjusting the height of the bulging part by tightening or loosening the adjusting screw, the size of the dent can be easily adjusted.

[0020] In the sixth invention, in any one of the second to fifth inventions, The taper cone drive shaft is provided with a rotatable pin that can move forward and backward, and an engagement hole for engaging the rotatable pin is formed in the cam follower or the ring member. When the rotatable pin retracts and the cam follower and the ring member rotate together, the outer diameters of the plurality of grinding wheels are kept constant without the taper cone moving up and down, and the inner surface with a true circular shape can be ground.

[0021] According to the above configuration, when the rotatable pin is engaged with the engagement hole, the cam follower or the ring member in which the engagement hole is formed is in a connected state with the taper cone drive shaft, the cam follower and the ring member rotate relative to each other, and the taper cone moves up and down according to the unevenness of the ring member, and at least a part of the circumferential direction of the inner surface with a circular cross section is processed to be recessed more than other parts. On the other hand, when the engagement between the cam follower or the ring member in which the engagement hole is formed and the taper cone drive shaft is released when the rotatable pin retracts, the cam follower and the ring member rotate together without relative rotational movement. Thereby, the up and down movement of the taper cone disappears, so the outer diameters of the plurality of grinding wheels are kept constant, and it is possible to machine the inner surface with a true circular cross section without dents.

[0022] In the seventh invention, It is directed to a honing method for machining at least a part of the circumferential direction of the inner surface with a circular cross section in the workpiece to be recessed more than other parts. In the honing method, A rotatable tool shaft, A plurality of grinding wheels are arranged on the tool shaft so as to be able to move forward and backward in the radial direction and rotate integrally with the tool shaft. A taper cone drive shaft provided inside the tool shaft and moving up and down. A taper cone provided at the lower end of the taper cone drive shaft and configured to move the plurality of grinding wheels radially in and out by moving up and down, Prepare a honing machine having a taper cone drive unit that drives the taper cone up and down, Create a timing chart so as to move the taper cone up and down in accordance with the recess in the circular inner surface of the cross section, Control the taper cone drive unit in accordance with the timing chart, and move the taper cone up and down to grind the circular inner surface of the cross section while expanding or contracting the plurality of grinding wheels.

[0023] According to the above configuration, for example, a timing chart is created in consideration of the rotational speed and rotational angle of the tool shaft, the inclination of the taper cone, and the movement amount of the plurality of grinding wheels, and the control unit controls the taper cone in accordance with the timing chart, so that at least a part of the circumferential direction of the circular inner surface of the workpiece can be processed to be recessed more than other parts without changing the setup.

[0024] In the eighth invention, in the seventh invention, The workpiece is a hydrodynamic bearing, and the recess on the inner surface is an oil film pocket.

[0025] According to the above configuration, a hydrodynamic bearing having an oil film pocket with low manufacturing cost can be obtained.

Advantages of the Invention

[0026] As described above, according to the present invention, since the plurality of grinding wheels can be expanded or contracted in accordance with the unevenness of the inner surface of the workpiece without changing the setup during honing, it is possible to process at least a part of the circumferential direction of the circular inner surface of the workpiece to be recessed more than other parts with high accuracy in fewer steps by honing.

Brief Description of the Drawings

[0027]

Figure 1

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Figure 13

Figure 14

Mode for Carrying Out the Invention

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0029] (Embodiment 1) Figs. 1 to 4 show the honing machine 1 according to Embodiment 1 of the present invention. This honing machine 1 is used to machine at least a part of the circumferential direction of the inner surface of a circular cross-section of a workpiece 50 shown in Fig. 5, for example, to make it recessed more than other parts. In this embodiment, the workpiece 50 is, for example, a hydrodynamic bearing, the recess on the inner surface is an oil film pocket 51, and the other constant minimum inner diameter part is a true circle part 52. Note that the workpiece 50 is not limited to a hydrodynamic bearing, and it may be any workpiece as long as at least a part of the circumferential direction of its inner surface of a circular cross-section is recessed more than other parts.

[0030] The honing machine 1 is provided with a tool shaft 2 that can be rotated by a tool motor (not shown). The rotational speed and rotational torque of the tool shaft 2 are appropriately set according to the grinding wheel 4 and the workpiece 50 to be used.

[0031] A plurality of grinding wheels 4 are provided in a grinding wheel slit 2a that extends vertically and is formed in the enlarged cylindrical portion at the lower end of the tool shaft 2 so as to be able to advance and retreat in the radial direction and rotate integrally with the tool shaft 2. In this embodiment, three grinding wheels 4 are provided, but one or more grinding wheels may be provided. The grinding wheel 4 is attached to the outer side in the radial direction of an expansion plate 5 that enters and exits the grinding wheel slit 2a.

[0032] Inside the tool shaft 2, a tapered cone drive shaft 3 that moves up and down is provided. This tapered cone drive shaft 3 itself does not rotate together with the tool shaft 2, but can move in the vertical direction along its axis by an up-and-down drive actuator (not shown). The up-and-down drive actuator is composed of a cylinder, a motor, etc. that utilize hydraulic pressure, pneumatic pressure, or electricity.

[0033] At the lower end of this tapered cone drive shaft 3, a tapered cone 7 is provided that advances and retreats a plurality of grinding wheels 4 in the radial direction by moving up and down. In this embodiment, the tapered cone 7 has two tapered portions 7a up and down, and the cylindrical cone upper end portion 7b is connected to the lower end of the tapered cone drive shaft 3 via a thrust bearing 9. Note that the lower tapered cone 7 is biased downward by a biasing member 6, but the configuration of the biasing member 6 is not particularly limited.

[0034] The configuration of the taper cone driving unit that vertically drives the taper cone drive shaft 3 is not particularly limited. In this embodiment, it is configured by the above-described vertical driving actuator. Different embodiments of the taper cone driving unit will be described later as Embodiment 2.

[0035] The honing machine 1 is provided with a control unit 8 that controls the entire operation thereof. Although not shown in detail, the control unit 8 is, for example, composed of a programmable logic controller (PLC). The control unit 8 is configured to control the vertical driving actuator so as to move the taper cone 7 up and down in accordance with the recess in the inner surface of the circular cross section, and to expand or contract the plurality of grinding wheels 4.

[0036] -Method for honing a workpiece- Next, a honing method for machining at least a part of the circumferential direction of the inner surface of the circular cross section of the workpiece 50 according to this embodiment so as to be recessed more than other parts will be described.

[0037] First, prepare the honing machine 1 described above.

[0038] Then, as shown in FIG. 7, a timing chart is created so as to move the taper cone 7 up and down in accordance with the recess in the inner surface of the circular cross section of the workpiece 50. In FIG. 7, the vertical axis L indicates the amount of rise and fall of the taper cone 7, and the horizontal axis t indicates time. In this embodiment, for example, a timing chart is created in consideration of the rotational speed and rotational angle of the tool shaft 2, the inclination of the taper cone 7, and the moving amount of the plurality of grinding wheels 4.

[0039] In accordance with this timing chart, the control unit 8 controls the taper cone driving unit, moves the taper cone 7 up and down, and grinds the inner surface of the circular cross section while expanding or contracting the plurality of grinding wheels 4.

[0040] Specifically, as shown in FIG. 3, when the grinding wheel is reduced in diameter, the tapered cone 7 is at the upper end, the descent amount L is 0, and the protrusion of the plurality of grinding wheels 4 is minimized. As shown in FIG. 6(a), the grinding wheel 4 is located at the position of the true circular portion 52 of the workpiece 50, and the minimum inner diameter of the workpiece 50 is ground.

[0041] On the other hand, after a predetermined time in the timing chart, the tapered cone drive unit is driven, and the tapered cone 7 begins to move downward (the descent amount L increases according to the timing chart). Then, the plurality of grinding wheels 4 gradually expand in diameter and begin to grind the oil film pocket 51. Then, as shown in FIGS. 4 and 6(b), when the tapered cone 7 has moved the most downward, the portion with the largest inner diameter of the oil film pocket 51 is ground.

[0042] In this way, by the control unit 8 controlling the ascent and descent amounts of the tapered cone 7 in accordance with the timing chart, at least a part (the oil film pocket 51) in the circumferential direction of the inner surface of the cross-sectional circular shape of the workpiece 50 is machined so as to be recessed more than the true circular portion 52. For this reason, there is no need for setup change for downward movement using a jig as in the prior art.

[0043] Therefore, according to the honing machine 1 according to the present embodiment, since the plurality of grinding wheels 4 can be expanded or reduced in diameter according to the unevenness of the inner surface of the workpiece 50 during honing, at least a part in the circumferential direction of the inner surface of the cross-sectional circular shape of the workpiece 50 can be machined to be recessed more than other parts with high accuracy in fewer steps. Thereby, a hydrodynamic bearing having an oil film pocket 51 with low manufacturing cost and good quality can be obtained.

[0044] (Embodiment 2) FIGS. 8 to 12 show the main part of the honing machine 101 according to Embodiment 2 of the present invention, and are different from the above Embodiment 1 in that no timing chart is used. In each of the following embodiments, the same parts as those in FIGS. 1 to 6 are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0045] In this embodiment, a ring member 108 with unevenness formed at intervals in the circumferential direction so as to move the tapered cone 107 up and down in accordance with the recess on the inner surface of the circular cross-section is provided at the upper end portion 107b of the tapered cone 107.

[0046] Further, between the lower end of the tapered cone drive shaft 3 and the ring member 108, a cam follower 109a is provided which abuts against the ring member 108 and moves up and down relatively in accordance with the unevenness of the ring member 108, thereby moving the tapered cone 107 up and down.

[0047] As shown enlarged in Fig. 9, the ring member 108 has a bulging portion 108a formed in accordance with the recess on the inner surface of the workpiece 50. That is, the height of the bulging portion 108a is designed to correspond to the size for moving the tapered cone 7 downward and expanding the diameter of the plurality of grinding wheels 4. The height of the lowest flat portion 108b corresponds to the outer diameter of the plurality of grinding wheels 4 with reduced diameter for grinding the true circular portion 52. For example, when the top of the oil film pocket 51 is recessed by 3 μm and the taper angle of the tapered cone 107 is 30°, the apex height of the bulging portion 108a is set to 3×√3 = 5.2 μm, enabling the desired shape to be ground.

[0048] A through-hole 108c is formed at the center of the ring member 108. In this embodiment, the number of the bulging portions 108a is three in accordance with the number of the oil film pockets 51, but it is not limited thereto. In Fig. 9, the height of the bulging portion 108a is exaggeratedly drawn. For example, in accordance with the actual oil film pocket 51 being about 3 μm to 10 μm, the bulging height of the bulging portion 108a is about 5.2 μm to 17.3 μm.

[0049] On the one hand, the cam follower 109a is composed of a roller that can ride on the relatively bulging portion 108a. In this embodiment, the number of cam followers 109a is three in accordance with the number of bulging portions 108a. The cam follower 109a is provided at the lower end of a cylindrical adapter 109. At the center of the lower end of this adapter 109, a cylindrical portion 109b is formed concentrically with the through hole 108c of the ring member 108, and this cylindrical portion 109b is inserted into the through hole 108c.

[0050] As shown in FIG. 8, the tool shaft 2 is provided with a rotatable pin 110 that can move forward and backward. The number of rotatable pins 110 is not particularly limited, but in this embodiment, there are two. The rotatable pin 110 can be moved up and down by an actuator (not shown) or manually. In this embodiment, engaging holes 109c with which the respective rotatable pins 110 engage are formed at the upper ends of the upper adapters 109.

[0051] When grinding a hydrodynamic bearing having an oil film pocket 51, the rotatable pin 110 is inserted into the engaging hole 109c, whereby the tapered cone drive shaft 3 and the adapter 109 are connected, the tapered cone 107 rotates together with the tool shaft 2, and the tapered cone 107 pushed against the cam follower 109a in accordance with the ridge of the ring member 108 descends or ascends, so that the plurality of grinding wheels 4 are expanded or contracted in diameter.

[0052] On the other hand, when the rotatable pin 110 retracts and the connection between the adapter 109 and the tapered cone drive shaft 3 is released, the adapter 109 becomes rotatable with respect to the tapered cone drive shaft 3 via the thrust bearing 9, and the adapter 109 and the ring member 108 that rotates together with the tool shaft 2 rotate together. Thereby, the outer diameter of the plurality of grinding wheels 4 is kept constant without the tapered cone 7 moving up and down, and it is configured to be able to grind an inner surface having a true circular shape.

[0053] -Honing processing method for workpiece- Next, the honing processing method according to this embodiment will be described.

[0054] Basically, the tapered cone 107 realizes the same movement as the timing chart shown in FIG. 7 of Embodiment 1. First, when the tool shaft 2 is stopped, the cam follower 109a is in contact with the flat portion 108b of the ring member 108, and the tapered cone 107 is at the upper end. The rotation pin 110 is lowered and inserted into the engagement hole 109c.

[0055] Then, when the tool shaft 2 starts to rotate, the cam follower 109a relatively rotates so as to start riding on the bulging portion 108a of the ring member 108 that rotates with the tool shaft 2 at a predetermined time (predetermined rotation angle), and the tapered cone 107 gradually descends. Thereby, the plurality of grindstones 4 gradually expand in diameter, and the oil film pocket 51 starts to be machined.

[0056] When the tool shaft 2 further rotates, the cam follower 109a is pushed against the apex of the bulging portion 108a and the tapered cone 107 descends to the lowest position. As shown in FIG. 6(b), the plurality of grindstones 4 are expanded to the maximum diameter, and the maximum diameter portion of the oil film pocket 51 is ground.

[0057] Next, when the cam follower 109a that has exceeded the apex of the bulging portion 108a reaches the flat portion b of the ring member 108, the tapered cone 107 returns to the highest position, and as shown in FIG. 6(a), the circular portion 52 is ground.

[0058] These movements are repeated in accordance with the rotation of the ring member 108.

[0059] In this way, by moving the tapered cone 107 up and down in accordance with the bulge of the ring member 108 to expand or contract the plurality of grindstones 4, at least a part of the circumferential direction of the inner surface of the circular cross-section in the workpiece 50 can be machined so as to be recessed more than other parts.

[0060] Therefore, in the present embodiment, when the trailing pin 110 is engaged with the engagement hole 109c of the adapter 109, since the ring member 108 rotates with the tool shaft 2, the tapered cone 107 moves up and down according to the unevenness of the ring member 108, and at least a part of the circumferential direction of the inner surface with a circular cross-section can be processed so as to be recessed more than other parts.

[0061] On the other hand, when the trailing pin 110 retracts and the engagement between the adapter 109 and the tapered cone drive shaft 3 is released, since the adapter 109 is connected to the tapered cone drive shaft 3 via the thrust bearing 9, the adapter 109 and the ring member 108 rotate together. As a result, the vertical movement of the tapered cone 7 disappears, so that the outer diameters of the plurality of grinding wheels 4 are kept constant, and the inner surface can be machined into a perfect circle.

[0062] -Modification Example- In this modification example, as shown in FIGS. 11 and 12, the ring member 108 is provided with an adjustment screw 108d' that can adjust the height of the bulging portion 108a' by rotation.

[0063] Specifically, the bulging portion 108a' is composed of a deformable metal plate or the like, and the flat portion 108b does not deform. Below the bulging portion 108a', a pushing pin 108e' is provided, and this pushing pin 108e' is configured to rise by screwing in the adjustment screw 108d'. The bulging portion 108a' is suitable for a steel plate or the like that is difficult to wear.

[0064] For example, the height of the bulging portion 108a' can be adjusted according to the tightening angle of the adjustment screw 108d'.

[0065] With this configuration, by tightening or loosening the adjustment screw 108d', the height of the bulging portion 108a' can be finely adjusted, and thus the size of the recess of the oil film pocket 51 can be easily adjusted.

[0066] In addition, when the ring member 108’ wears, by slightly screwing the adjustment screw 108d’, there is also an advantage that the height of the bulging portion 108a’ can be slightly adjusted downward. Further, if the height of the bulging portion 108a’ is made the same as the height of the flat portion 108b, the tapered cone 107 does not move up and down, and an inner surface machining with a true circular shape can be performed.

[0067] (Other Embodiments) The present invention may be configured as follows for each of the above embodiments.

[0068] That is, in each of the above embodiments, as an example of the control unit 8 (controller), a programmable logic controller (PLC) has been described. However, the control unit 8 may be physically configured in any manner as long as it controls the honing machine 1. For example, the control unit 8 may utilize software (program) such as a microcomputer or the like. Alternatively, the control unit 8 may be realized by combining hardware (circuit components).

[0069] In the above-described Embodiment 2, the adapter 109 is provided on the tapered cone drive shaft 3 side, and the ring member 108 is provided on the tapered cone 107 side. However, conversely, the ring member 108 may be provided on the tapered cone drive shaft 3 side, and the adapter 109 may be provided on the tapered cone 107 side. In that case, an engagement hole is provided on the ring member 108 side.

[0070] Note that the above embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

Explanation of Reference Numerals

[0071] 1 Honing Machine 2 Tool Shaft 2a Slit for Grinding Stone 3 Tapered Cone Drive Shaft 4 Grinding Stone 5 Expansion Plate 6 Biasing Member 7 Tapered Cone 7a tapered portion 7b upper end portion 8 control unit 9 thrust bearing 50 workpiece 51 oil film pocket 52 round portion 101 honing machine 107 taper cone 107b upper end portion 108 ring member 108a, 108a’ bulging portion 108b flat portion 108c through hole 108d’ adjusting screw 108e’ lifting pin 109 adapter 109a cam follower 109b cylindrical portion 109c engaging hole 110 follower pin

Claims

1. A honing machine for machining at least a part of the circumferential direction of the inner surface of a workpiece having a circular cross-section to be recessed more than other parts, comprising: a rotatable tool shaft; a plurality of grinding wheels disposed on the tool shaft so as to be movable forward and backward in the radial direction and rotating integrally with the tool shaft; a tapered cone drive shaft provided inside the tool shaft and movable up and down; a tapered cone provided at the lower end of the tapered cone drive shaft and moving up and down to move the plurality of grinding wheels forward and backward in the radial direction; a tapered cone drive unit for moving the tapered cone up and down in accordance with the recess of the inner surface having a circular cross-section to expand or contract the plurality of grinding wheels. A honing machine characterized by the above.

2. A honing machine for machining at least a part of the circumferential direction of the inner surface of a workpiece having a circular cross-section to be recessed more than other parts, comprising: a rotatable tool shaft; a plurality of grinding wheels disposed on the tool shaft so as to be movable forward and backward in the radial direction and rotating integrally with the tool shaft; a tapered cone drive shaft provided inside the tool shaft and movable up and down; a tapered cone provided at the lower end of the tapered cone drive shaft and moving up and down to move the plurality of grinding wheels forward and backward in the radial direction; a ring member provided on the tapered cone, having unevenness formed at intervals in the circumferential direction so as to move the tapered cone up and down in accordance with the recess of the inner surface having a circular cross-section; a cam follower provided on the tapered cone, contacting while relatively rotating with respect to the ring member, and moving the tapered cone up and down relatively in accordance with the unevenness of the ring member. A honing machine characterized by the above.

3. The ring member has a bulging portion formed in accordance with the recess of the inner surface of the workpiece. The cam follower is composed of a roller capable of riding on the bulging portion. The honing machine according to claim 2, characterized by the above.

4. The bulging portion of the ring member is configured to be height-adjustable. The honing machine according to claim 3, characterized by the above.

5. The ring member is provided with an adjustment screw capable of adjusting the height of the bulging portion by rotation. The honing machine according to claim 4, characterized by the above.

6. The taper cone drive shaft is provided with a rotatable pin that can move forward and backward, and an engagement hole for engaging the rotatable pin is formed in the cam follower or the ring member. When the rotatable pin retracts and the cam follower and the ring member rotate together, the outer diameters of the plurality of grinding wheels are kept constant without the taper cone moving up and down, and the inner surface having a true circular shape can be ground. The honing machine according to any one of claims 2 to 5, characterized in that.

7. A honing method for machining at least a part of the circumferential direction of a circular inner surface in a cross section of a workpiece to be recessed more than other parts, A rotatable tool shaft, A plurality of grinding wheels arranged on the tool shaft so as to be able to move forward and backward in the radial direction and integrally rotating with the tool shaft, A taper cone drive shaft provided inside the tool shaft and moving up and down, A taper cone provided at the lower end of the taper cone drive shaft and moving up and down to move the plurality of grinding wheels forward and backward in the radial direction, Prepare a honing machine having a taper cone drive unit for driving the taper cone up and down, Create a timing chart so as to move the taper cone up and down in accordance with the recess of the circular inner surface in the cross section, Control the taper cone drive unit in accordance with the timing chart, and grind the circular inner surface in the cross section while moving the taper cone up and down to expand or contract the plurality of grinding wheels. The honing method is characterized in that.

8. The workpiece is a hydrodynamic bearing, and the recess on the inner surface is an oil film pocket. The honing method according to claim 7, characterized in that.

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