JP2002283112A - Boring bar and boring apparatus having boring bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust each diameter of knife edges of one or a plurality of cutters arranged in the circumferential direction with a simple structure. SOLUTION: A boring bar 20 is adjustable in its knife edge diameter and a boring apparatus uses the boring bar. The boring apparatus is provided with a body shaft 22 of the boring bar 20 and an adjusting shaft 50 inserted therein. A plurality of cutter fitting pats 24A, 24B are arranged in the circumferential direction on the body shaft 22, and a plurality of cam faces corresponding thereto are formed on the outer peripheral surface of the adjusting shaft 50 inserted in the body shaft 22. The cutter fitting parts 24A, 24B have cutter holding members 26A, 26B moving in the radial direction of the body shaft with cutters 28A, 28B held thereon, and a drive pin 29 is projected on a cam face side. An elastic pressing part 30 is provided in a position adjacent in the axial direction of the body shaft relative to the cutter holding members 26A, 26B, thereby elastically pressing the respective cutter holding members 26A, 26B inward in the radial direction to keep the contact state of the drive pin 29 and the cam face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boring bar having a cutting edge diameter adjustable and a boring machine provided with the boring bar.

[0002]

2. Description of the Related Art Conventionally, as a boring bar configured so that the cutting edge diameter can be adjusted, for example, Japanese Utility Model 7-4
What is shown in 8326 gazette is known. FIG. 8 shows the structure.

[0003] The illustrated main body shaft 2 extends in the depth direction of the figure, and a cutting tool holding member 4 extending in the diametric direction (vertical direction in the figure) is provided at an appropriate position of the main body shaft 2 so as to be movable in the diametric direction. , The outer end of the blade holding member 4 (the lower end in the figure)
A cutting tool 5 for boring is fixed to the body.

In the blade holding member 4, a flange 4 a is formed at an end (upper end in the figure) opposite to the blade 5, and the flange 4 a is a bottomed recess formed in the main body shaft 2. 2
a. A compression coil spring 6 interposed between the bottom surface of the concave portion 2a and the flange portion 4a is provided in the concave portion 2a, and the resilient force of the spring 6 causes the blade tool holding member 4 to move upward in the drawing, that is, the blade tool. 5 is urged in a direction to retreat radially inward of the main body shaft 2.

[0005] A rectangular through hole 7 penetrating the blade holding member 4 in the axial direction of the main body shaft 2 is provided at an intermediate portion thereof.
The adjustment shaft 8, which is also rectangular, is inserted into the through hole 7 with a gap in the longitudinal direction of the blade holder 4. The outer peripheral surface (lower surface in the figure) of the adjusting shaft 8 on the side of the cutting tool 5 is a cam surface 8a whose height in the radial direction changes depending on the axial position. The cam surface 8a and the inner surface 7a of the through hole 7 Is maintained by the elastic force of the compression coil spring 6.

In this configuration, if the adjusting shaft 8 having the cam surface 8a is slid in the axial direction, the blade holding member 4 is displaced in the longitudinal direction by an amount corresponding to a change in height of the cam surface 8a accompanying the sliding. The cutting edge diameter of the cutting tool 5 can be changed by the displacement.

[0007]

In the above-described boring bar, there is a demand that a plurality of cutting tools 5 be arranged side by side in the circumferential direction of the main body shaft 2 for the purpose of improving the cutting feed speed, for example. However, in the boring bar shown in FIG. 8, the cutting tool holding member 4 substantially penetrates the main body shaft 2 in the diametrical direction, and the resilient force of the compression coil spring 6 provided on the side opposite to the cutting tool 5 causes the cutting tool holding member. Because of the configuration in which the biasing force is applied, it is structurally difficult to arrange a plurality of cutting tools 5 in the circumferential direction of the main body shaft 2, and even if they can be arranged, their cutting edge diameters are collectively adjusted. It is impossible to do.

In view of such circumstances, the present invention provides a boring bar capable of adjusting the respective cutting edge diameters of a plurality of cutting tools arranged in the circumferential direction with a simple structure, and a boring machine having the boring bar. The purpose is to provide.

[0009]

As a means for solving the above-mentioned problems, the present invention relates to a cylindrical main body shaft having a cutting tool mounting portion on which a boring tool is mounted so that the blade tip diameter can be adjusted. An adjusting shaft, which is inserted inside the main body shaft and has a cam surface formed on an outer peripheral surface and whose height in the radial direction changes according to an axial position, relative movement of the adjusting shaft in the axial direction with respect to the main body shaft. Is a boring bar configured such that the cutting edge diameter of the cutting tool provided in the cutting tool mounting portion changes according to the shape of the cam surface, wherein the cutting tool mounting portion is located at a plurality of positions arranged in the circumferential direction of the main body shaft. A plurality of cam surfaces respectively corresponding to these cutting tool mounting portions are formed on the outer peripheral surface of the adjustment shaft, and each cutting tool mounting portion holds the cutting tool, and the main body is formed on the outer peripheral portion of the main body shaft. Moveable in the radial direction of the shaft And a cutting tool holding member having a contact portion that comes into contact with a predetermined cam surface of the adjusting shaft, and a cutting tool holding member provided at a position adjacent to the cutting tool holding member in the axial direction of the main body shaft. An elastic pressing portion for maintaining the contact state between the contact portion and the cam surface by elastically pressing the cutting tool holding member radially inward of the main body shaft from an adjacent position.

[0010] The present invention also provides the boring bar, rotation supporting means for rotatably supporting the boring bar around its own axis, rotation driving means for driving the boring bar to rotate, and an adjusting shaft for the boring bar. A cutting edge diameter adjusting means for changing the cutting edge diameter of the cutting tool in the cutting tool mounting portion by moving the cutting tool forward and backward in the axial direction with respect to the main body shaft while allowing rotation about its own axis. is there.

According to the above arrangement, in each of the blade mounting portions, the elastic pressing portion for pressing the blade holding member radially inward is provided at a position axially adjacent to the blade holding member. The adjustment shaft can be inserted into the center of the main body shaft while the plurality of blade mounting portions are arranged side by side on the outer periphery of the main shaft. Then, by shifting the axial position of each cam surface formed on the adjustment shaft, the radial position of each cutting tool holding member that is in contact with the cam surface is changed, thereby simultaneously changing the cutting edge diameter of each cutting tool. Can be adjusted.

Here, the specific number and arrangement of the blade mounting portions are not limited, but if these blade mounting portions are arranged at equal intervals in the circumferential direction of the main body shaft, a single blade mounting portion is provided. It is possible to improve the rotational balance as compared with a structure provided only with the above, and it is possible to obtain a configuration suitable for high-speed rotation.

[0013] The cutting tool attached to each of the cutting tool mounting portions,
All may be of the same type, and in this case, the cutting feed speed can be improved by the number of sheets.

Further, if the cutting tool includes a cutting tool for rough working (including a cutting tool for semi-finishing) and a cutting tool for finishing, that is, if both tools are used in combination, the boring bar itself is replaced. Without using a single boring bar, both roughing and finishing can be performed, and the processing efficiency can be improved.

Specifically, the cam surface of the adjusting shaft formed for the finishing tool includes an inclined surface whose height in the radial direction changes continuously depending on its axial position, and has the same axial direction as the inclined surface. The cam surface of the adjusting shaft formed about the rough cutting tool at the position includes a flat surface having a uniform radial height, and the maximum value of the cutting edge diameter of the finishing tool adjusted by the inclined surface is flat. The cutting edge diameter of the rough cutting tool is larger than the cutting edge diameter of the rough cutting tool adjusted by the surface, and the minimum value of the cutting edge diameter of the finishing tool set by the inclined surface is adjusted by the flat surface. If the configuration is such that the shape of each cam surface is set to be smaller than the above, the cutting edge diameter of the rough processing blade is made larger than the blade diameter of the finishing blade by operating the adjustment shaft. In the roughing, the roughing using the cutting tool can be performed, and then the finishing axis is adjusted by operating the adjustment shaft so that the cutting edge diameter of the finishing tool is larger than the cutting edge diameter of the rough cutting tool. Finishing using a cutting tool can be performed.

The elastic holding portion is attached to the main body shaft so as to be swingable about an axis substantially orthogonal to the axial direction of the main body shaft, and one of the swinging ends of the elastic holding portion is attached to the cutting tool holding member. The engaged presser lever and the swinging end of the presser lever engaged with the cutting tool holding member apply elastic force to the pressing lever in a direction to press the cutting tool holding member radially inward. What includes a biasing means is preferable.

According to this configuration, the elastic pressing portion is attached to the blade holding member by a simple structure in which the swinging end of the pressing lever is engaged with the blade holding member to urge the pressing lever in the pressing direction. On the other hand, the cutting tool holding member can be elastically pressed inward in the radial direction while being arranged at a position adjacent to the main body shaft in the axial direction.

In this configuration, when the boring bar is rotated at a high speed, the centrifugal force acting on the cutting tool holding member causes the cutting tool holding member to float radially outward against the pressing force. Is generated around the swing axis of the presser lever, but it is possible to obtain a moment that cancels the moment by using a centrifugal force acting on a rear portion of the presser lever.

Further, a moment about the swing axis due to a centrifugal force acting on a lever portion opposite to the cutting tool holding member with the swinging shaft of the holding lever as a boundary, the lever portion on the cutting tool holding member side and the cutting tool. If the moment around the swing axis due to the centrifugal force acting on the holding member is made greater, the centrifugal force is effectively used, and the force by which the holding lever presses the blade holding member is increased in reverse. And the blade edge diameter can be made more stable.

For example, if a weight portion made of a material having a higher specific gravity than the other portion is provided at a lever portion opposite to the blade holding member with the swing axis of the holding lever as a boundary, the shape of the holding lever can be improved. Can be increased without increasing the moment due to the centrifugal force acting on the lever portion on the side opposite to the blade holding member.

Preferably, the biasing means applies elastic force to the end of the holding lever opposite to the blade holding member from radially inward to outward of the main body shaft. According to this configuration, by disposing the urging means inside the presser lever, the urging force (elastic force) of the proper direction is applied to the presser lever while avoiding an increase in the diameter of the boring bar.
Can be provided.

More specifically, a pressing member that abuts on an end of the holding lever opposite to the blade holding member in a direction from the radially inner side to the outer side of the main body shaft, and presses the pressing member in the direction. And a spring member that biases the spring member.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to FIGS.

The boring apparatus according to this embodiment comprises a processing apparatus main body 11 shown in FIG. 1 and a cutting edge diameter adjusting apparatus 12 shown in FIG.
It is set on 0.

The processing apparatus main body 11 includes a cylindrical rotation support member 14 that opens to the front and back, and a rotation support cylinder 16 is supported inside the rotation support member 14 via a bearing so as to be rotatable around the front and rear axis. A pulley 17 is fixed to a rear portion of the rotation support cylinder 16, and the pulley 17 is connected to an output shaft of an electric motor (rotation driving means) (not shown) via a belt 18. A boring bar 20 is fixed to the front end of the rotation support cylinder 16 so as to extend coaxially forward from the cylinder 16.

As shown in FIGS. 3 to 6, the boring bar 20 has a main body shaft 22. The main body shaft 22 has a cylindrical shape having a shaft insertion hole 21 on its central axis. The adjustment shaft 50 is inserted into the inside 21 with almost no gap.

At the front of the main body shaft 22, there are provided three semi-finishing cutting tool mounting portions 24A and one finishing cutting tool mounting portion 24B. These four blade attachment portions 24A and 24B are arranged at equal intervals (90 ° intervals in the illustrated example) in the circumferential direction.

In each of the blade mounting portions 24A and 24B,
Recesses 22a and 22b are dug from the outer peripheral surface of the main body shaft 22 radially inward to a predetermined depth, respectively.
The tool holding members 26A and 26B are respectively fitted into the body 22b so as to be movable in the radial direction of the main body shaft 22. And
Concave portion 2 formed at the outer end of three blade holding members 26A
7, a blade 28A for semi-finishing is fixed, and a blade 28B for finishing is fixed to a concave portion 27 formed at the outer end of one blade holding member 26B.

Driving pins (contact portions) 29 project radially inward from the blade holding members 26A and 26B, and these driving pins 29 penetrate through the bottom walls of the recesses 22a and 22b in the radial direction and are commonly used. In the shaft insertion hole 21.

The outer end of each drive pin 29 is in contact with an adjusting screw shaft 25 as shown in FIG. Each adjustment screw shaft 25
Are screw holes 26 formed in the blade holding members 26A and 26B.
s is screwed from the outside in the radial direction, and by adjusting the screwing depth, the relative position between each drive pin 29 and the blade tools 28A, 28B fixed to the blade tool holding members 26A, 26B is adjusted. The processing diameter is adjusted.

At positions adjacent to the blade holding members 26A and 26B in the axial direction of the main body shaft 22 (rear positions of the blade holding members 26A and 26B in the illustrated example), these blade holding members 26A and 26B are set to have a diameter. An elastic pressing portion 30 that elastically presses the inner side in the direction is provided.

More specifically, a lever storage groove 22c extends rearward from each of the recesses 22a and 22b, and a holding lever 31 is stored in each lever storage groove 22c. Each presser lever 31 is attached to the main body shaft 22 so that the front-rear direction intermediate portion can swing around a swing shaft 32 in a direction orthogonal to the axial direction of the main body shaft 22, and has a front swing end portion. 31a is engaged with the cutting tool holding members 26A and 26B. More specifically, insertion holes 26h that open rearward are formed in each of the blade tool holding members 26A and 26B, and the front swing ends 31a are inserted into these insertion holes 26h, respectively. 31a and blade holding member 26
A and 26B are displaced in the radial direction almost integrally.

On the other hand, the rear half of the presser lever 31 (the part behind the pivot shaft 32) is a weight 31b made of a material having a higher specific gravity than the part on the front side. The specific material is not particularly limited.
In the case where the material of the front part of the first part is a steel material, the weight 3
As the material of 1b, an alloy containing tungsten as a main component (specific gravity of 17 or more) or the like is suitable. Also, this weight 31
The location of b may not necessarily be the entire rear half of the presser lever 31, and even if it is provided locally only at the rear end, for example, a certain effect can be obtained. In the illustrated example, the weight portion 31b of the holding lever 31 and a portion on the front side thereof are integrated by welding.

At the rear swing end 31b, a pressure receiving surface 31c having a normal direction obliquely rearward from the inside is formed.
An elastic force is applied to the pressure receiving surface 31c from the urging means 34 in a direction substantially parallel to the normal direction.

The urging means 34 includes a pressing member 36 and a compression coil spring 38. The pressing member 36 has a cap shape that opens rearward and has a pressing projection 36a formed on the top wall thereof. The pressing member 36 moves in the same direction along the normal direction into the concave portion 22d formed on the main body shaft 22. It is inserted so as to be possible. The compression coil spring 38 is interposed in a compressed state between the back surface of the top wall of the pressing member 36 and the bottom surface of the concave portion 22d.
a is pressed against the pressure receiving surface 31c.

That is, the pressing projection 36a of the pressing member 36
Elastically presses the rear swinging end 31b of the holding lever 31 in a direction from the radially inner side to the outer side of the main body shaft 22, and the pressing force causes the holding lever 31 to move toward the front swinging end 31a. Are biased in a direction of pressing the blade holding members 26A, 26B radially inward, and the biasing force causes the inner ends of the drive pins 29 of the blade holding members 26A, 26B and the respective adjustment shafts 50 to be described later. The state of contact with the cam surface is maintained.

In front of the blade holding members 26A, 26B, front and rear surfaces of the members 26A, 26B and the recesses 22a, 22B are provided.
A pressing means 40 is provided for eliminating rattling due to a gap (gap in the front-rear direction) with the inner side surface of b. The pressing means 40 includes a pressing pin 41 and a compression coil spring 42.
These are housed in through holes provided in the main body shaft 22 along the axial direction. Specifically, the pressing pin 41 is mounted on the blade tool holding members 26A and 26B (rear side), and a stopper 44 is fixed on the opposite side (front side), and interposed between the stopper 44 and the pressing pin 41. The pressing pin 41 is pressed against the front side surfaces of the cutting tool holding members 26A and 26B by the resilient force of the compression coil spring 42, and the rear side surface (the right side surface in FIG. 3) of the cutting tool holding members 26A and 26B is pressed by the pressing force. It is pressed against the inner surfaces of the recesses 22a and 22b without any gap.

Further, with respect to the blade holding member 26B of the finishing blade 28B which requires high processing accuracy, the moment around the tip of the drive pin 29 due to the pressing force applied from the pressing lever 31 to the blade holding member 26B is canceled. The structure for performing is provided. Specifically, the pressed portion 26c moves forward from the main body of the blade holding member 26B.
Is extended, and a concave portion 26d that opens radially outward is formed in the pressed portion 26c, while a cover 46 that covers the concave portion 26d from the radial outside is fixed to the outer peripheral surface of the main body shaft 22. A compression coil spring 48 is interposed between the bottom of the recess 26d and the compression coil spring 48. Due to the elastic force of the compression coil spring 48, a moment opposite to the moment due to the pressing force of the presser lever 31 is generated around the distal end of the drive pin 29.

The adjusting shaft 50 has a round shaft shape which is inserted into the shaft support hole 21 of the rotary shaft 16 and the shaft insertion hole 21 of the body shaft 22 with almost no gap. The cam surface for semi-finishing and one cam surface for finishing are formed side by side in the circumferential direction, and the drive pin 29 of the cutting tool holding member 26A is provided on the cam surface for semi-finishing and the cutting tool is provided on Drive pin 29 of holding member 26B
But, each comes into contact.

The cam surface for semi-finishing is a rear flat surface 52A, and the main shaft 2 is larger than the rear flat surface 52A.
2 having a large (in other words, shallow) front flat surface 54A in the radial direction, and both flat surfaces 52A, 54A.
Are connected by a smooth step surface. Each flat surface 52
A and 54A extend in the axial direction of the adjustment shaft 50 and are flat surfaces whose radial height does not change in the axial direction (that is, the radial height is uniform).

On the other hand, the cam surface for finishing includes a rear inclined surface 52B and a front inclined surface 54B whose radial height of the main body shaft 22 is larger (in other words, shallower) than the rear inclined surface 52B. The two inclined surfaces 52B and 54B are connected by a smooth step surface.
Are formed at the same axial position as the flat surfaces 52A and 54A, respectively. Each of the inclined surfaces 52B and 54B extends in the axial direction of the adjustment shaft 50, and is inclined such that the radial height continuously increases (that is, becomes shallower) toward the front.

Further, the shape of each cam surface is as follows:
Blade 28 when drive pin 29 is in contact with the front end of B
B blade diameter (that is, the maximum value of the blade diameter of the blade 28B adjusted by the inclined surface 52B)]> [the blade diameter of the blade 28A when the drive pin 29 is in contact with the flat surface 52A]> [the inclined surface 52B The blade tip diameter of the blade 28B when the drive pin 29 is in contact with the rear end (that is, the inclined surface 52B
(Minimum value of the cutting edge diameter of the cutting tool 28B adjusted by the above), and the driving pin 2 is provided at the front end of the inclined surface 54B.
9 (in other words, the maximum value of the edge diameter of the blade 28B adjusted by the inclined surface 54B) >> [the blade 28A when the drive pin 29 is in contact with the flat surface 54A]. Of the blade 28B when the drive pin 29 is in contact with the rear end of the inclined surface 54B (that is, the blade 2 adjusted by the inclined surface 54B).
8B (minimum value of the cutting edge diameter of 8B)].

For example, in FIG. 3, the cutting edge diameter of the cutting tool 28B when the driving pin 29 is in contact with the point a of the inclined surface 52B is smaller than the cutting edge diameter of the cutting tool 28A, The shapes of the inclined surface 52B and the flat surface 52A are set so that the cutting edge diameter of the cutting tool 28B when the driving pin 29 is in contact is larger than the cutting edge diameter of the cutting tool 28A. When the driving pin 29 is in contact with the cutting tool 28B, the cutting edge diameter of the cutting tool 28B becomes smaller than the cutting edge diameter of the cutting tool 28A.
The blade diameter of the blade 28B when the blade is in contact with the blade 28A
The shapes of the inclined surface 54B and the flat surface 54A are set so as to be larger than the cutting edge diameter.

The blade diameter adjusting device 12 shown in FIG. 2 moves the adjusting shaft 50 back and forth (that is, in the axial direction) while allowing its rotation. Specifically, the blade tip diameter adjusting device 12 includes a transmission shaft 58 connected to a rear end of the adjustment shaft 50 via a joint 56, and a shaft holding member 60 that rotatably holds the rear end of the operation shaft 58. And a slide device 62 for sliding the shaft holding member 60 in the front-rear direction.

The shaft holding member 60 extends vertically.
A bearing 64 for rotatably supporting the rear end of the operation shaft 58 is provided at an upper portion thereof. The outer ring of the bearing 64 is completely fixed to the shaft holding member 60 side, while the inner ring is sandwiched from the front and rear by a step 59 formed on the transmission shaft 58 and a nut 63 fixed to the tip thereof. With this structure, the shaft holding member 60 and the operation shaft 58 are connected so as to integrally move back and forth while being rotatable relative to each other. A screw hole 66 is provided at a lower end portion of the shaft holding member 60 so as to penetrate the shaft holding member 60 in the front-rear direction, and a slider 72 is fixed at an intermediate portion.

The slide device 62 includes a device main body 68 fixed on the table 10, and the main body 68 is provided with a guide rail 70 extending forward and backward, and the slider 72 is fitted to the guide rail 70. Thus, the shaft holding member 60 is slidably supported in the front-rear direction.

A servo motor 74, which is a slide drive source, is fixed forward at the rear end of the apparatus main body 68, and a rear portion of a drive shaft 76 extending forward and backward is rotatable via a bearing 75 in front of the servo motor 74. The rear end of the drive shaft 76 and the output shaft of the servomotor 74 are connected via a joint 78. On the other hand, a feed screw portion 80 is formed at the front of the drive shaft 76, and the feed screw portion 80
Are screwed into the screw holes 66 of the shaft holding member 60.

Accordingly, the operation of the servo motor 74 causes the drive shaft 80 to rotate, and the shaft holding member 60 screwed with the feed screw portion 80 allows the transmission shaft 58 and the adjustment shaft 50 to rotate while allowing the two shafts 58 to rotate. , 50 integrally with each other in the front-rear direction (axial direction).

The cutting edge diameter adjusting device 12 may be any device as long as it allows the adjusting shaft 50 to move in the axial direction while permitting rotation, and its specific structure is not particularly limited.

Next, the outline of boring using this apparatus will be described.

1. Initial setting As shown in FIG. 3, the drive pin 29 of the blade holding member 26B
The front and rear position of the adjustment shaft 50 is adjusted so that the inner end of the adjustment shaft 50 comes to the point a of the inclined surface 52B of the adjustment shaft 50. At this axial position, the cutting edge diameter of the cutting tool 28B for finishing is smaller than the cutting edge diameter of the cutting tool 28A for medium finishing.
It becomes a state in which processing can be performed exclusively by the intermediate finishing blade 28A.

2. Semi-finishing The rotation driving means (not shown) is operated to rotate the entire boring bar 20 at a high speed integrally with the rotation support cylinder 16. Further, by moving the table 10 forward, the boring bar 20 is transferred to the workpiece, and the semi-finishing cutting tool 28A is brought into contact with the inner peripheral surface of the workpiece machining hole, thereby semi-finishing the inner peripheral surface of the workpiece. The chamfering of the peripheral edge of the machining hole entrance is also performed by a chamfering blade 28C provided at the rear portion of the main body shaft 22.

At this time, the cutting tool 28A for semi-finishing is used.
Are arranged in the circumferential direction of the main body shaft 22 (three in the example in the figure), so that the cutting feed speed is remarkably increased as compared with a single blade 28A. In addition, the cutting edge diameter of each semi-finishing cutting tool 28 </ b> A can be simultaneously adjusted by the common adjustment shaft 50.

Further, in this embodiment, since the plurality of blade attachment portions 24A and 24B are arranged at equal intervals in the circumferential direction, the configuration is good in rotational balance and suitable for high-speed rotation.

Further, since the weight portion 31b having a large specific gravity is provided at the rear portion of each holding lever 31, the centrifugal force acting on this portion is large, so that the moment about the swing shaft 32 due to the centrifugal force is large. Become. This moment cancels out the moment due to the centrifugal force acting on the front half of the presser lever 31 and the blade holding member 26A (that is, the moment for causing the blade holding members 26A and 26B to float outward in the radial direction against the urging force). By increasing this moment, it is possible to ensure that the tool holding members 26A and 26B are pressed down even during high-speed rotation.

In particular, by increasing the centrifugal force acting on the weight portion 31b by increasing the specific gravity or volume of the weight portion 31b, the cutting tool holding member 26A with the swing shaft 32 as a boundary.
(26B), the moment around the pivot axis due to the centrifugal force acting on the lever portion (mainly the weight portion 31b; hereinafter referred to as the lever rear portion) acting on the lever portion 26A (2).
If the moment around the swing axis 32 due to the centrifugal force acting on the lever portion on the 6B) side (hereinafter referred to as the lever front portion) and the blade holding member is made larger,
With the rotation of the boring bar 20, the presser lever 31
It is possible to enhance the pressing force of the blade tool holding members 26A, 26B due to the pressure.

More specifically, as shown in FIG. 7, the center of gravity of the front portion of the lever and the blade holding member 26A (26B) is G1, the centrifugal force acting on it is F1, and the center of gravity G1 is the swing shaft 3.
Assuming that the distance to L2 is L1, the center of gravity of the rear part of the lever is G2, the centrifugal force acting on this is F2, and the distance from the center of gravity G2 to the swing shaft 32 is L2, F1 · L1 <F2 · L2. do it.

Here, the lever front part and the blade holding member 26
The mass of A (26B) is M1, the mass of the rear part of the lever is M2,
The turning radius of the center of gravity G1 is R1, and the turning radius of the center of gravity G2 is R.
2. If the angular velocity of the main body shaft 22 is ω, the centrifugal force F1 is M
1 · R1 · ω ^2, since the centrifugal force F2 becomes M2 · R2 · ω ^2, after all, should be set the parameters such that the M1 · R1 · L1 <M2 · R2 · L2.

Incidentally, such a moment balance is as follows.
In addition to providing the weight portion 31b, for example, it is also possible to extend the rear portion of the lever long rearward.

3. Finishing process The adjustment shaft 50 is retracted from the above position, and its inclined surface 52B
The driving pin 29 of the cutting tool holding member 26B is brought into contact with the point b. At this axial position, the blade diameter of the finishing blade 28B is larger than the blade diameter of the semi-finishing blade 28A (that is, the blade diameter is reversed).
By sending the boring bar 20 in the axial direction (relative movement with respect to the workpiece) in a direction opposite to that during the intermediate finishing while bringing the cutting edge of the finishing tool 28B into contact with the inner peripheral surface of the workpiece hole, the finishing is performed. I do. At the time of this finishing, it is preferable to set the rotation speed and the feed speed of the boring bar 20 to appropriate values according to the material of the work and the cutting tool 28B and the required surface roughness.

Here, in the conventional boring bar to which only a single kind of cutting tool is attached, the boring bar to be used must be replaced when shifting from semi-finishing to finishing, thereby improving the processing efficiency. Was difficult, but according to the boring bar shown in this embodiment, it is not necessary to replace the boring bar, and the adjusting shaft 50 is retracted to enlarge the cutting edge diameter of the finishing cutting tool 28B. With only a simple operation, it is possible to quickly switch from semi-finishing to finishing.

If the diameter of the cutting edge is reduced due to wear of the finishing cutting tool 28B during the repeated processing, the adjusting shaft 50 is retracted by the reduced amount to drive the driving pin 29 on the inclined surface 52B. May be shifted to the front side (for example, shifted to the point c in FIG. 3). Thereby, an appropriate finishing diameter can be obtained regardless of the wear of the cutting tool 28B.

4. Processing of Large Diameter Work When processing a work having a large hole diameter, the adjustment shaft 50 is largely retracted from the position shown in FIG. 3 so that the driving pin 29 of the blade holding member 28B comes into contact with the point A in FIG. . As a result, the edge diameters of the blades 28A and 28B are both enlarged, and the edge diameter of the intermediate finishing blade 28A is larger than the edge diameter of the finishing blade 28B, so that the intermediate finishing blade 28A is used. Medium finishing of large diameter workpieces. Then, the drive pin 29
Is shifted to the point B, and the semi-finishing tool 2
By reversing the cutting edge diameter of 8A and the cutting edge diameter of the finishing tool 28B, it is possible to perform finishing work on a large-diameter work.

The embodiment of the present invention is not limited to the above-described embodiment, and may take the following forms as an example.

In the present invention, for example, only the cutting tool for rough machining (the cutting tool 28A for semi-finishing in the above embodiment) may be arranged on the boring bar 20, and in this case,
For example, the flat surfaces 52A and 54 as shown in FIG.
By setting the cam surface having A, the cutting edge diameter can be switched. Also, the rough cutting tool may be configured so that the diameter of the cutting edge can be continuously adjusted similarly to the above-mentioned finishing tool (that is, an inclined surface is set as a cam surface).

In the above-described embodiment, the boring bar 20 including three intermediate finishing tools 28A and one finishing processing tool 28B is disclosed. What is necessary is just to set suitably according to etc.

The means for biasing the presser lever 31 is not limited to the one shown in the figure. For example, even if a torsion coil spring is provided around the swing shaft 32, the elastic force in the pressing direction can be applied to the presser lever 31. It is possible to give. Further, instead of the illustrated combination of the pressing member 36 and the compression coil spring 38, for example, an elastic material such as rubber may be arranged at the same location and pressed against the pressure receiving surface 31 c of the holding lever 31.

Further, the structure of the elastic holding portion is not limited to the structure using the holding lever 31. For example, the elasticity of the compression coil spring 48 shown in FIG. You may make it press on a radial inside.

[0069]

As described above, according to the present invention, a plurality of cutting tool mounting portions are juxtaposed in the circumferential direction of the main body shaft, and the elastic holding portion for pressing the cutting tool holding member elastically inward in the radial direction is provided. By providing at a position adjacent to the member in the axial direction of the main body shaft, it is possible to insert the adjustment shaft at the center thereof,
Since a plurality of cam surfaces for adjusting the cutting edge diameter of each cutting tool are formed on the adjusting shaft, a plurality of cutting tools arranged in the circumferential direction by a relative displacement between the adjusting shaft and the main body shaft. Can be adjusted with a simple structure, thereby contributing to an improvement in machining efficiency and the like.

[Brief description of the drawings]

FIG. 1 is a sectional front view showing a processing apparatus main body of a boring apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional front view showing a blade tip diameter adjusting device of the boring device.

FIG. 3 is a sectional front view showing a main part of a boring bar of the boring device.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a sectional view taken along line BB of FIG. 3;

FIG. 6 is a sectional view taken along line CC of FIG. 3;

FIG. 7 is an explanatory diagram showing a moment generated around a pivot axis of a holding lever in the boring bar.

FIG. 8 is a sectional side view showing an example of a blade tip diameter adjusting structure in a conventional boring bar.

[Explanation of symbols]

14 Rotation Support Member (Rotation Support Means) 16 Rotation Support Cylindrical Body (Rotation Support Means) 20 Boring Bar 22 Main Body Shaft 24A, 24B Blade Attachment 26A, 26B Blade Holder 28A Medium Finishing Blade (Rough Cutting Blade) 28B Finishing cutting tool 29 Drive pin (contact part) 30 Elastic holding part 31 Holding lever 31a Front swing end part 31b Weight part 32 Swing shaft 34 Urging means 36 Press member 38 Compression coil spring 50 Adjusting shaft 52A, 54A Flat Surface (constituting cam surface for semi-finishing) 52B, 54B Inclined surface (constituting cam surface for finishing)

Claims (10)

[Claims] 1. A cylindrical main body shaft having a cutting tool mounting portion to which a cutting tool for boring is mounted so that the cutting edge diameter can be adjusted,
An adjusting shaft, which is inserted inside the main body shaft and has a cam surface whose radial height changes depending on the axial position, formed on the outer peripheral surface, and the adjusting shaft is relatively moved with respect to the main body shaft in the axial direction. A boring bar configured such that a cutting edge diameter of a cutting tool provided on the cutting tool mounting portion changes according to a shape of the cam surface, wherein the cutting tool mounting portion is provided at a plurality of positions arranged in a circumferential direction of the main body shaft. A plurality of cam surfaces respectively corresponding to these blade mounting portions are formed on the outer peripheral surface of the adjustment shaft, and each blade mounting portion holds the blade, and the main body shaft is mounted on the outer peripheral portion of the main body shaft. A cutting tool holding member having a contact portion that is mounted to be movable in the radial direction and has a contact portion that comes into contact with a predetermined cam surface of the adjustment shaft, and is adjacent to the cutting tool holding member in the axial direction of the main body shaft. Provided in position And an elastic pressing portion for maintaining the contact state between the contact portion and the cam surface by elastically pressing the cutting tool holding member radially inward of the main body shaft from an adjacent position thereof. Bowling bar to do. 2. The boring bar according to claim 1, wherein said plurality of cutting tool mounting portions are arranged at equal intervals in a circumferential direction of a main body shaft. 3. The boring bar according to claim 1, wherein the cutting tool attached to each of the cutting tool mounting portions includes a rough processing cutting tool and a finishing processing cutting tool. 4. The boring bar according to claim 3, wherein the cam surface of the adjusting shaft formed on the finishing tool includes an inclined surface whose height in the radial direction continuously changes depending on its axial position. The cam surface of the adjustment shaft formed on the rough cutting tool at the same axial position as the inclined surface includes a flat surface having a uniform radial height, and the finishing tool adjusted by the inclined surface. The maximum value of the cutting edge diameter is larger than the cutting edge diameter of the roughing cutting tool adjusted by the flat surface, and the minimum value of the cutting edge diameter of the finishing cutting tool adjusted by the inclined surface is adjusted by the flat surface. A boring bar characterized in that the shape of each cam surface is set so as to be smaller than the cutting edge diameter of the rough processing blade tool to be used. 5. The boring bar according to claim 1, wherein the elastic pressing portion is attached to the main body shaft such that the elastic pressing portion can swing about an axis substantially perpendicular to an axial direction of the main body axis. A holding lever having one swing end engaged with the cutting tool holding member, and a swing end of the holding lever engaged with the cutting tool holding member radially inward of the cutting tool holding member. And a biasing means for applying an elastic force to the pressing lever in a direction of pressing the boring bar. 6. The boring bar according to claim 5, wherein the press lever has a moment about the swing axis due to centrifugal force acting on a lever portion opposite to the blade holding member with the swing axis as a boundary. A boring bar, wherein the boring bar is configured to be larger than a moment about the swing axis due to a centrifugal force acting on the lever portion on the blade holding member side and the blade holding member. 7. The boring bar according to claim 6, wherein a weight portion made of a material having a higher specific gravity than other portions is provided on a lever portion opposite to the blade holding member with the swing axis of the holding lever as a boundary. A bowling bar characterized by being made. 8. The boring bar according to claim 5, wherein the biasing means is radially inward of the main body shaft with respect to an end of the holding lever opposite to the blade holding member. A boring bar characterized by applying elastic force outward from the boring bar. 9. The boring bar according to claim 8, wherein the biasing means is arranged so as to extend from an inner side in a radial direction of the main body shaft to an outer side with respect to an end of the pressing lever opposite to the blade holding member. A boring bar comprising: a pressing member that abuts; and a spring member that urges the pressing member in the direction. 10. A boring bar according to claim 1, wherein said boring bar is rotatably supported around its own axis, and a rotation drive means for rotating said boring bar. Cutting edge diameter adjusting means for changing the cutting edge diameter of the cutting tool in the cutting tool mounting portion by moving the adjusting shaft of the boring bar in the axial direction with respect to the main body axis while allowing rotation about its own axis. A boring machine characterized by the following.