JP2010228034A - Inner diameter grinding tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inner diameter grinding tool having a simple structure and a reliable operation of a diameter expansion mechanism of a grinding part even when a plurality of grinding parts (grinding stones) are provided in the axial direction.
SOLUTION: The electromagnetic valve 14 is closed and the contact pressure between the piston 17 and the draw bar 4 is reduced to move the draw bar 4 in the axial direction. In this state, the thrust motor 8 is driven to move the draw bar 4 in the axial direction. The diameter of the grindstone 12 (grinding part 3) is expanded by moving. Further, the electromagnetic valve 14 is opened while the draw bar 4 is moved in the axial direction, and oil from the hydraulic pump 15 is fed into the hydraulic pipe 13 to increase the pressure in the hydraulic pipe 13. Then, the piston 17 moves radially outward to support the draw bar 4 from the inside. By supporting the draw bar 4 from the inside, the movement of the grindstone 12 (grinding part 3) in the radial direction is prevented and a locked state is established.
[Selection] Figure 2

Description

  The present invention relates to an inner diameter grinding tool for performing honing processing or the like on the inner surface of a hole formed in a workpiece with a drill or the like.

  When a workpiece with multiple grinding parts along the axial direction, such as a crank journal bearing formed by combining a cylinder block and a lower block, is to be ground (polished) with a normal inner diameter grinding tool, the tool body ( Arbor) interferes with the workpiece. Therefore, Patent Documents 1 and 2 propose processing tools that can adjust the protruding amount of the blade in the radial direction.

In Patent Document 1, a slit is formed in a cylindrical member (arbor), and a grindstone is provided in the slit so that it can protrude and retract in the radial direction. A draw bar having a tapered portion is inserted into the cylindrical member, and the draw bar is moved in the axial direction. As a result, a structure has been proposed in which a grindstone having a tapered surface in sliding contact with the tapered surface of the draw bar expands.

Patent Document 2 proposes a structure in which the diameter of the grindstone is increased by inserting a screw shaft having a tapered cone portion from the tip end side of the tool instead of the draw bar, and moving the screw shaft forward and backward in the axial direction.

Japanese Patent Laid-Open No. 10-249706 JP-A-8-192352

A tool having a diameter expanding function of a grinding part as disclosed in Patent Documents 1 and 2 has a structure in which axial movement of a draw bar is directly transmitted to a grindstone via a tapered surface. In order to simultaneously process a long workpiece with multiple processing points using a tool having such a diameter expanding function of the grinding part, the length of the holder (arbor), grinding part and draw bar must be increased. It is difficult to manufacture.

Even if it can be manufactured, the problem of bending of the entire tool occurs. That is, on the tip side, the axes of the draw bar and the holder do not coincide with each other, and the processing accuracy is lowered.

Therefore, it is also possible to individually provide grinding parts having a diameter expanding function at a plurality of positions in the axial direction of the long holder, and to form tapered parts for expanding the grinding part on the draw bar for each grinding part. Conceivable. However, in order to make the amount of protrusion in the radial direction of the grinding part uniform for each grinding part, the shape of the taper part of the draw bar must be machined extremely accurately, and the radial direction of the grinding part also depends on assembly errors. The amount of protrusion will be crazy.

  In order to solve the above-mentioned problems, an inner diameter grinding tool according to the present invention holds a grinding part movably in a radial direction in a cylindrical tool holder rotated by a spindle, and the diameter of the grinding part is held in the cylindrical tool holder. In an internal diameter grinding tool through which a draw bar for adjusting the direction protrusion amount is inserted, a hydraulic pipe is inserted into the cylindrical tool holder inside the draw bar, and a cylinder is disposed at a position corresponding to the grinding portion of the hydraulic pipe. The cylinder is provided with a piston that presses the draw bar radially outward by the action of hydraulic pressure.

  The grinding part may be provided at one location in the axial direction of the cylindrical tool holder. However, when machining a workpiece having a plurality of machining locations, such as a crank journal bearing, at the same time, the plurality of grinding portions are arranged on the axis of the cylindrical tool holder. It is preferable that they are provided apart in the direction. In consideration of the rotational balance, it is preferable to provide a plurality of grinding parts at equal intervals in the circumferential direction.

  It is also possible to divide the cylindrical tool holder into a plurality of parts in the axial direction and connect them with a bolt or the like to form one tool holder.

In the inner diameter grinding tool according to the present invention, the axial movement of the draw bar is not directly changed to the protruding amount in the radial direction of the grinding portion. The diameter of the grinding part is expanded and this state is maintained, so even if there are multiple grinding parts along the axial direction, hydraulic pressure does not act on the piston when moving the draw bar in the axial direction. By setting the state, the resistance when moving the draw bar in the axial direction is small, and the operation can be performed smoothly.

Further, since the resistance when moving the draw bar in the axial direction is small, a large force does not act on the members constituting the diameter expansion mechanism. Therefore, the configuration of the diameter expansion mechanism can be reduced in size and simplified.

Sectional drawing of the state where the internal diameter grinding tool according to the present invention grinds the crank journal bearing Sectional drawing along the axial direction of the internal diameter grinding tool which concerns on this invention AA arrow view of FIG. Perspective view of the base end of the draw bar (A) is an axial direction expanded sectional view of the state which stored the grinding part in a holder, (b) is a radial direction expanded sectional view. (A) is an axially enlarged sectional view in a state where the grinding part protrudes in the radial direction from the holder, and (b) is an enlarged sectional view in the radial direction.

Preferred embodiments will be described below with reference to the accompanying drawings. In this embodiment, as shown in FIG. 1, in order to grind the crank journal bearing formed by combining the cylinder block W1 and the lower block W2, the inner diameter grinding tool has a plurality of grinding portions.

The inner diameter grinding tool according to the present invention has a cylindrical tool holder 2 attached to one end portion of a holder 1 rotated by a spindle motor M, and a plurality of grinding portions 3 are provided apart from each other in the axial direction of the cylindrical tool holder 2. ing. The positions of the grinding portions 3 are locations corresponding to the crank journal bearings, and a pair of grinding portions 3 are provided at 180 ° apart in the circumferential direction at each grinding location.

A pair of draw bars 4, 4 are inserted into the cylindrical tool holder 2, and the draw bars 4, 4 pass through the holding body 1, and their base ends are fixed to a ring 5. The ring 5 is a support plate. A nut 7 is provided on a part of the support plate 6, and a ball screw 9 that is rotated by a thrust motor 8 is screwed onto the nut 7.

Thus, by driving the thrust motor 8 to rotate the ball screw 9, the pair of draw bars 4, 4 connected to the support plate 6 moves in the axial direction. In addition, the taper part 4a which determines the radial direction protrusion amount of the grinding part 3 is formed in the location corresponding to each grinding part 3 of the draw bars 4 and 4. FIG.

The grinding section 3 includes a retainer 10 that holds the draw bar 4 from the inside, and a grindstone 12 that is secured to the retainer 10 by bolts 11. Diamond abrasive grains and CBN are secured to the surface of the grindstone 12 by electrodeposition. Has been. In addition, you may attach cutting tools other than a grindstone.

A hydraulic pipe 13 is inserted into the cylindrical tool holder 2 inside the draw bar 4. The distal end portion of the hydraulic pipe 13 is closed, and the proximal end portion is connected to the hydraulic pump 15 via the electromagnetic valve 14.

A cylinder 16 is disposed at a location corresponding to each grinding part 3 of the hydraulic pipe 13. The cylinder 16 penetrates the hydraulic pipe 13 and the retainer 10 in the radial direction, and a piston 17 that receives hydraulic pressure radially outward is disposed in the cylinder 16.

In the above, each grinding part 3 is stored in the cylindrical tool holder 2 when the grinding operation is not performed. This storing operation is performed by closing the electromagnetic valve 14. That is, when the electromagnetic valve 14 is closed, the hydraulic pressure in the hydraulic pipe 13 is reduced, and as shown in FIGS. It moves radially inward by a spring member or the like and is stored in the cylindrical tool holder 2.

On the other hand, in order to project each grinding part 3 radially outward from the outer peripheral surface of the cylindrical tool holder 2 by a predetermined amount, first, the contact pressure between the piston 17 and the draw bar 4 is reduced with the electromagnetic valve 14 closed. The draw bar 4 is easily moved in the axial direction.

Next, the thrust motor 8 is driven to move the draw bar 4 in the axial direction. Then, since the grindstone 12 has the taper surface 12a which slidably contacts the taper surface 4a of the draw bar 4, the grindstone 12 (grinding part 3) expands in diameter.

Further, the electromagnetic valve 14 is opened while the draw bar 4 is moved in the axial direction, and the oil from the hydraulic pump 15 is fed into the hydraulic pipe 13 to increase the pressure in the hydraulic pipe 13. Then, as shown to Fig.6 (a), (b), the piston 17 moves to radial direction outer side, and supports the draw bar 4 from inner side. By supporting this draw bar 4 from the inside, the movement of the grindstone 12 (grinding portion 3) in the radial direction is prevented and a locked state is established.

When the diameter of the grindstone 12 is increased by a predetermined amount by the above procedure, the center of the hole of the workpiece is aligned with the axis of the inner diameter grinding tool, and the cylindrical motor holder 2 is rotated at a high speed by the spindle motor M. Advancing along, grind the inner diameter of the hole in the workpiece.

The inner diameter grinding tool according to the present invention can be used in the field of grinding inner peripheral surfaces such as journal bearings.

DESCRIPTION OF SYMBOLS 1 ... Holding body, 2 ... Cylindrical tool holder, 3 ... Grinding part, 4 ... Draw bar, 4a ... Tapered surface of draw bar, 5 ... Ring, 6 ... Support plate, 7 ... Nut, 8 ... Thrust motor, 9 ... Ball screw, DESCRIPTION OF SYMBOLS 10 ... Retainer, 11 ... Bolt, 12 ... Grinding wheel, 12a ... Tapered surface of grinding wheel, 13 ... Hydraulic pipe, 14 ... Electromagnetic valve, 15 ... Hydraulic pump, 16 ... Cylinder, 17 ... Piston
W1 ... Cylinder block, W2 ... Lower block, M ... Spindle motor.

Claims (2)

In a cylindrical tool holder that is rotated by a spindle, a grinding part is held so as to be movable in the radial direction, and an internal diameter grinding tool in which a draw bar that adjusts a radial protrusion amount of the grinding part is inserted in the cylindrical tool holder, A hydraulic pipe is inserted into the cylindrical tool holder inside the draw bar, and a cylinder is disposed at a position corresponding to the grinding portion of the hydraulic pipe. An internal diameter grinding tool, wherein a piston for pressing the draw bar is provided. 2. The internal diameter grinding tool according to claim 1, wherein a plurality of the grinding parts are arranged apart from each other in the axial direction of the cylindrical tool holder, and the cylinder is provided corresponding to each grinding part. Inner diameter grinding tool.