JP3118313B2 - Profile cutting machine for inner wall of pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for copying an inner surface of a pipe such as a seamless steel pipe.

[0002]

2. Description of the Related Art The inner wall of a steel pipe such as a seamless pipe has been ground by a grinder. However, this processing method is inefficient, and continuous internal cutting with a cutting tool has been attempted. Further, instead of such a method, the present applicant has proposed, for example, Japanese Utility Model Application No. 1-128247, which has higher accuracy and higher productivity.
There is an application published as -65608. This is a boring head equipped with a cutting tool, which is provided with a fixed shoe and a copying shoe.The copying shoe is elastically applied to the inner wall of the pipe, and a uniform cutting allowance is obtained regardless of the degree of eccentricity and roundness. This enables cutting.

[0003] The basic structure of such a copying machine is that a plurality of shoes are incorporated into a boring head and one of the shoes is movable so as to follow the shape of the inner wall of the pipe. is there. As the copying mechanism, a mechanism that receives a copying shoe by a spring and moves the shoe while following the inner wall of the tube by an elastic reaction force is adopted.

[0004]

In the case where cutting is advanced by copying, including the one described in the above-mentioned publication, the shoe comes into contact with the inner wall of the pipe and is separated from the shoe by using the copying by these. Cutting is performed by the cutting tool arranged on the boring head at the position of.

On the other hand, in the conventional structure, when the boring head is inserted into the pipe, for example, two shoes are opposed to each other in the radial direction of the boring head in view of the fact that it is difficult to work due to the interference of the cutting tool. In many cases, the shoe is positioned so that one shoe is located between the shoes. In this way, the three shoes are gathered in a half area of the peripheral surface of the boring head, and no trouble occurs when the shoes are inserted into the pipe.

However, in the case of scanning cutting, it is better to arrange the shoes around the boring head at a substantially equal circumferential pitch, in consideration of the instability of the cutting surface due to the bending deformation of the bar connecting the boring head, etc. Is possible. Therefore, the conventional arrangement of the shoes around the boring head cannot cope with the processing requiring high precision, and the bending of the bar greatly affects the processing precision.

Further, in the combination of the fixed shoe and the copying shoe, if the inner wall has a spiral unevenness such as a spiral steel pipe, the following of the cutting tool becomes insufficient.
Further, when cutting a portion having a large inner diameter, since the cutting tool follows the cutting tool with a spring, the pressing force is weakened, which is likely to be one cause of a decrease in accuracy.

As described above, in the conventional copying apparatus of the copying method, there is a limit to the improvement of the accuracy due to the arrangement of the shoes in the circumferential direction and the inclusion of the one fixed in the shoes.

The problem to be solved in the present invention is to improve the machining accuracy and the cutting speed by further improving the followability of the cutting tool to the inner wall of the tube.

[0010]

SUMMARY OF THE INVENTION The present invention provides a rotary driving device for holding one end of a pipe and rotating the pipe around its axis, a boring bar capable of moving back and forth in the axial direction of the pipe, and a tip end of the boring bar. A boring head mounted and insertable into the tube, comprising:
The boring head is provided with at least three movable shoes movable toward the inner wall of the pipe, and a hydraulic oil chamber is provided inside the boring head for applying a hydraulic pressure with the movable shoes facing outward. A cutting tool for cutting the inner wall of the tube, and a rolling element having a circumferential surface located on the center side of the cutting surface formed by the cutting tool and rolling the inner wall of the tube in a circumferential direction on the peripheral surface of the movable shoe; An oil chamber is provided with a piston whose end face in the axial direction faces, and elastic means for urging the piston toward the hydraulic oil chamber is provided, and the piston is used when the pressure of hydraulic oil in the hydraulic oil chamber fluctuates. It is characterized as a buffer.

[0011]

The movable shoe incorporated in the boring head is urged toward the inner wall side of the pipe by the pressure of the hydraulic oil in the hydraulic oil chamber, and the rolling element of the movable shoe is brought into contact with the inner wall of the pipe so that the movable shoe is fixed by a cutting tool. We cut with the cutting allowance.
Since the plurality of movable shoes are held by the common operating oil pressure, it becomes possible to cut the bite of each movable shoe into the inner wall of the pipe with uniform strength.

When one movable shoe hits the convex portion of the inner wall of the tube and is pushed toward the center of the boring head, the hydraulic oil is compressed. At this time, pressure is transmitted via the hydraulic oil to the piston facing the hydraulic oil chamber, and as a result, the piston moves outward to increase the volume of the hydraulic oil chamber. For this reason, the pressure of the hydraulic oil in the hydraulic oil chamber does not increase even when compressed by the movement of the movable shoe,
It is kept constant. Therefore, the movable shoe is always urged toward the inner wall side of the pipe by a constant operating oil pressure, so that even if there are local irregularities on the cutting surface, it is possible to perform cutting with a uniform cutting allowance.

[0013]

1 is a longitudinal sectional view showing a main part of a copying machine according to the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a schematic side view showing the entire machining apparatus. FIG.

In FIG. 3, a rotary drive unit 21 is disposed at one end of a bed 20, and a steel pipe P is supported by a chuck 22a of a face plate 22 provided on a drive shaft 21a of the rotary drive unit 21. The drive shaft 2 is provided on the upper surface of the bed 20.
A guide rail 20a is provided so as to be parallel to the axis of 1a, and a tube support frame 23 movable along the guide rail 20a and a feed device 24 for cutting the inner surface of the steel pipe P.
Are arranged respectively. The pipe support frame 23 is for rotatably supporting the steel pipe P through the steel pipe P. In addition, a screw shaft 25 is built in the bed 20,
The feeder 24 is provided with a pinion 24a that meshes with the pinion. Then, the screw shaft 25 is driven by a driving device (not shown).
The screw shaft 25 and the pinion 24
The feed device 24 moves right and left in the figure by the screw gear mechanism of FIG.

The boring bar 1 is attached to the feeder 24 so as to have an axis substantially aligned with the axis of the steel pipe P. A boring head 2 is provided at the tip of the boring bar 1 to enter the steel pipe P and cut the inner wall thereof.

The outside diameter of the boring head 2 is sufficiently smaller than the inside diameter of the steel pipe P, and the inside thereof includes a hydraulic oil chamber 2a.
Is opened in the axial direction, and one end thereof is connected to a hydraulic unit (not shown) and a flow path by a hydraulic pipe 3 provided in the boring bar 1. As shown in FIG. 2, three bores 2b are formed in the hydraulic oil chamber 2a so as to have axes in the radial direction. These bores 2b are 120 ° from each other
Are arranged radially so as to have a central angle, and have an opening cross section of a different diameter in which the inner diameter on the open end side is increased.

Each of the bores 2b incorporates a movable shoe 4 movable in the radial direction. These movable shoes 4
Has a substantially T-shaped vertical cross-section that fits tightly into the bore 2b, and the pressure of the hydraulic oil in the hydraulic oil chamber 2a reduces the radial position and the holding pressure of each movable shoe 4 with respect to the copying. Set. A coil spring 4a is mounted on the surface of the movable shoe 4 facing the outside of the boring head 2, and the coil spring 4a is abutted against a stopper 2c provided on the outer peripheral surface of the boring head 2, thereby moving the movable shoe 4 to the boring head. 2 toward the center.

At the end of the movable shoe 4, a cutting tool 5 and a rolling pad 6 as a rolling element are provided. The cutting tool 5 is detachably fixed to the movable shoe 4 as having a tip 5a having a posture corresponding to the direction in which the steel pipe P rotates clockwise as shown in FIG. The rolling pad 6 is rotatably supported by a support shaft 6 a fixed to the movable shoe 4, and is rotatable with a rotation axis parallel to the axis of the boring head 2. And byte 5
Is made smaller on the outer peripheral surface of the rolling pad 6 than the protruding length of the rolling pad 6.

A piston 7 is inserted coaxially from the outside into the hydraulic oil chamber 2a opened toward the tip end surface of the boring head 2, and the end surface of the piston 7 faces the hydraulic oil chamber 2a. The piston 7 is provided with a flange 7a halfway in the axial direction of the piston 7. The stroke is regulated by abutting the flange 7a against the end face of the boring head 2, and the upper limit of the amount of movement into the hydraulic oil chamber 2a is set.

On the end face of the boring head 2, a housing 8 surrounding the piston 7 is provided. A spring 8a, one end of which abuts against a flange 7a of the piston 7, is provided in the housing 8 as an elastic means. The spring 8a urges the piston 7 toward the boring head 2. The piston 7 is movably supported in the axial direction, and an adjusting screw 8b for changing the biasing force of the spring 8a by adjusting the distance between the piston 7 and the flange 7a is rotatably provided on the end face of the housing 8. .

Further, on the outer periphery of the base end side of the boring head 2, there are provided three guide rollers 9 which are used as guides when the boring head 2 is taken in and out of the steel pipe P.
These guide rollers 9 are arranged so that the central angle between them is 120 ° like the movable shoes 4, and have a phase difference of 60 ° with each movable shoe 4. . That is, the movable shoe 4 and the guide roller 9
Are arranged one after the other in the circumferential direction, and the arrangement angle pitch is set to 60 °.

These guide rollers 9 are rotatably mounted on a support shaft 9a fixed to the boring head 2, and are rotatable in the circumferential direction of the steel pipe P when it comes into contact with the inner wall of the steel pipe P. The projecting length of the peripheral surface of the guide roller 9 is smaller than the inner diameter of the steel pipe P and slightly longer than the minimum projecting length of the tip 5a of the cutting tool 5.

When the movable shoe 4 is exchanged according to the inner diameter of the steel pipe P, the support shaft 9a can be moved in the radial direction with respect to the boring head 2 so that the protrusion length of the guide roller 9 can be changed. It is preferable to attach to the holding block 9b incorporated.

In the above configuration, the procedure for cutting the inner wall of the steel pipe P is as follows.

First, the boring head 2 is put on standby in a state where the pressure of the hydraulic oil to the hydraulic oil chamber 2a by the hydraulic unit (not shown) is reduced. At this time, the movable shoe 4
1, the entire movable shoe 4 falls into the bore 2b, as shown on the lower side of the center line in FIG. 1, and the tip 5a of the cutting tool 5 is moved from the surface on which the peripheral surface of the guide roller 9 rolls. Also move to the center side. Therefore, all three movable shoes 4 are maintained in a state moved to the center side.
On the other hand, the hydraulic pressure applied to the piston 7 also decreases,
The piston 7 is moved by the urging force of the spring 8a as shown in FIG.
As shown by the alternate long and short dash line in FIG. 7, the flange 7a abuts against the end face of the boring head 2 and stops, and the tip of the piston 7 also approaches the bore 2b side.

Next, the feeder 24 is driven to insert the boring head 2 at the tip of the boring bar 1 into the steel pipe P while the steel pipe P held by the chuck 22a and the pipe support frame 23 is rotating slowly. In this work, the steel pipe P and the boring bar 1 may be aligned with each other.
Since all three movable shoes 4 are retracted to the center side of the boring head 2, only the guide roller 9 is
However, interference with the cutting tool 5 does not occur only by contacting the inner wall of the cutting tool.

The boring head 2 is moved by the feeding device 24.
Is inserted into the innermost part of the steel pipe P, cutting of the inner wall is started by the cutting tool 5 while moving the boring bar 1 to the right in FIG. This cutting is continuously performed by using a combined movement of the movement of the boring head 2 in the axial direction and the rotation of the steel pipe P by the rotation drive device 21.

At a stage before the cutting process, a hydraulic unit (not shown) is operated to increase the pressure of the hydraulic oil in the hydraulic oil chamber 2a until it reaches an appropriate value. Thereby, the movable shoe 4 moves in the radially expanding direction, and is set to a position indicated by the upper movable shoe 4 in FIG. At this time, due to the positional relationship between the rolling pad 6 and the cutting tool 5 described above, the cutting tool 5 bites into the wall of the steel pipe P by the operating oil pressure, and the rolling pad 6 is similarly strongly pressed against the inner wall of the steel pipe P by the operating oil pressure. Can be

On the other hand, due to the pressure increase of the hydraulic oil in the hydraulic oil chamber 2a, the piston 7 moves to the right as shown in FIG. 1, and the flange 7a moves away from the end face of the boring head 2. The moving distance of the piston 7 is determined by the balance between the operating oil pressure and the urging force of the spring 8a. When the adjusting screw 8b is moved to the right, the urging force of the coil spring 8a is weakened, and the moving distance of the piston 7 is increased. Conversely, when the adjusting screw 8b is moved to the left, the moving distance of the piston 7 becomes shorter.

The inner wall of the steel pipe P is cut by the cutting tool 5 arranged on the peripheral surface of the boring head 2 in FIG. 2 by the movement of the boring head 2 by the feed device 24 and the rotation of the steel pipe P by the rotary drive device 21. In this cutting process, the three movable shoes 4 receive the pressure of the common hydraulic oil, and cause the cutting tools 5 to bite into the inner wall of the steel pipe P with the same pressing force. The cutting allowance at this time is equal to the distance between the tip of the tip 5a and the peripheral surface of the rolling pad 6.

Here, as shown in FIG. 4, when the core of the boring head 2 is at the position K and the inner wall shape of the steel pipe P is circular, it is only necessary to set the boring head 2 coaxially with the steel pipe P. The sum of the amount of protrusion of each movable shoe 4 from the peripheral surface of the boring head 2 is always constant as shown in the following equation (1). For this reason, the rolling pad 6 of each movable shoe 4 rolls following the inner wall of the steel pipe P. In order to always maintain a constant pressing force, the inner wall of the steel pipe P is finished with a uniform cutting allowance by the cutting tool 5. Can be.

Further, even when the inner wall of the steel pipe P is elliptical and its center is at the position L in FIG. 4 and it is eccentric with respect to the boring head 2, scanning cutting can be performed similarly. That is, since each movable shoe 4 is urged outward by the pressure of the hydraulic oil in the common hydraulic oil chamber 2a, the movable shoes 4 are proportional to the reaction force that the rolling pad 6 receives from the inner wall of the steel pipe P. Moves to the center side. In other words, each movable shoe 4 is supported under a common operating oil pressure, so that when one moves toward the center, the other two move outward. Fluctuations in the volume of the working oil chamber 2a at that time are absorbed by the movement of the piston 7, and the working oil pressure is always kept constant. That is, as shown in the figure, if the distance from the core of the boring head 2 to the tip of each cutting tool 5 is a, b, and c as shown in the figure, the working oil pressure in the working oil chamber 2a is constant. , A + b + c = constant (1)

As described above, even if the shape of the inner wall of the steel pipe P is not a perfect circle, it is possible to perform cutting while following the three movable shoes 4 to the inner wall. It is constant over the entire circumference, and uniform cutting without idle cutting or excessive cutting can be performed. Such cutting can be performed not only on the longitudinal cross-sectional shape of the steel pipe P but also when bending or the like occurs in the axial direction. This is because the boring head 2 by the movable shoe 4 can move while following the deflection in the steel pipe P.

Here, if the cutting tool 5 comes into contact with the partially severe irregularities on the inner wall of the steel pipe P during the cutting process, the cutting reaction force also fluctuates greatly, and the movable shoe 4 is held by the operating oil pressure. Also, the cutting tends to be unstable.

On the other hand, when the cutting tool 5 hits the convex portion of the inner wall of the steel pipe P and the movable shoe 4 suddenly moves toward the center, the pressure of the working oil in the working oil chamber 2a is applied to the piston 7 as well. Is transmitted. For this reason, the piston 7 moves to the right in FIG. 1, and the capacity of the hydraulic oil chamber 2a increases, so that the pressure increase of the hydraulic oil is released. Therefore, the pressure of the hydraulic oil in the hydraulic oil chamber 2a is maintained at a normal value, and the holding pressure for each movable shoe 4 is kept constant irrespective of the fluctuation of the cutting reaction force.

As described above, even when the inner wall of the steel pipe P has large irregularities locally, each movable shoe 4 moves while following the inner wall of the steel pipe P by the rolling of the rolling pad 6. Therefore, no matter how the shape of the inner wall of the steel pipe P changes, the movable shoes 4 can always be held at a constant operating oil pressure, and the cutting tool 5 of each movable shoe 4 can be independently driven with a constant cutting force. Stable copying can be performed.

Further, the movable shoe 4 is guided by the rolling pad 6 which is not in surface contact with the inner wall of the steel pipe P but rolls in contact with the inner wall. Therefore, as compared with the sliding by the surface contact, the frictional force is reduced and the occurrence of chatter vibration is suppressed. Therefore, the boring head 2 can be stably held in the steel pipe P even with respect to the rotation of the steel pipe P and the feed of the boring head 2 in the axial direction, so that high-speed cutting can be performed and machining accuracy is improved.

The surface roughness Rt at this time is determined by the following formula:
(Mm / rev), and when the nose radius of the cutting tool is r (mm), the following equation (2) is generally satisfied.

Rt = (f ² / 8r) × 1000 (μm) (2) On the other hand, in the present invention, 3 is located at a position obtained by dividing the central angle into three with respect to the peripheral surface of the boring head 2. Since the cutting is performed by the number of cutting tools 5, when Expression (2) is replaced with the present invention, the following expression is given.

Rt = ((f / 3) ² / 8r) × 1000 (μm) (3) Here, as compared with the case of using a single byte, the size is about 1/9. Become. In other words, the feed amount F when cutting while maintaining the surface roughness Rt of a single cutting tool
Is given by the following equation.

Rt = (f ² / 8r) × 1000 = ((F / 3) ² / 8r) × 1000 (μm) (4) Therefore, from equation (4), f = F / 3, F = 3f
Can be expressed as Therefore, in the apparatus of the present invention, cutting can be performed with a feed amount three times as large as that when a single cutting tool is used, and as a result, the cutting time is also reduced.

When the cutting process is completed and the boring head 2 reaches the end of the steel pipe P by the feeder 24, the boring head 2 is removed from the steel pipe P. When the cutting by the cutting tool 5 is completed in a state where the end of the steel pipe P is considerably left, the work is first performed after the pressure of the working oil in the working oil chamber 2a is reduced by the hydraulic unit. Due to the pressure drop of the hydraulic oil in the hydraulic oil chamber 2a, the outward holding pressure received by the movable shoe 4 decreases, and the stopper 2
The movable shoe 4 is pushed toward the center of the boring head 2 by the restoring force of the coil spring 4a between the boring head 2 and the coil spring 4a. Thereby, the movable shoe 4 falls into the bore 2b as in the lower one in FIG. 1, the cutting tool 5 separates from the inner wall of the steel pipe P, and only the guide roller 9 comes into contact with the inner wall of the steel pipe P. Thereafter, when the steel pipe P is moved in the direction in which the boring bar 1 is pulled out by the feeder 24 while being slowly rotated by the rotation driving device 21, the guide roller 9 moves while rolling on the inner wall of the steel pipe P, and the boring head 2 is moved. It can be extracted from the steel pipe P.

When the cutting operation is interrupted due to the loss of the cutting tool 5 or the like, the same operation of pulling out the boring head 2 can be performed. On the other hand, even when the steel pipe P is pulled out in the direction of the cutting surface, only the guide roller 9 rolls on the inner wall of the steel pipe P almost along the cutting locus, so that the cutting tool 5 does not interfere with the steel pipe P after the cutting process. I will not impose it.

In the embodiment, the cutting of the inner wall of the steel pipe has been described. However, it is needless to say that the cutting apparatus of the present invention can be used for cutting the inner surface of other pipes.

[0045]

According to the present invention, since the plurality of movable shoes incorporated in the boring head are held by a common working oil pressure, the cutting tool can be cut into the inner wall of the pipe with a uniform strength by the tool bit of each movable shoe. , High-precision cutting becomes possible.

Further, since the fluctuation of the operating oil pressure is buffered by the piston, the movable shoe is always urged toward the inner wall side of the pipe by a constant operating oil pressure, and even if there is a local unevenness on the cutting surface, this is an obstacle. Processing can be performed at a high cutting speed without any problems, and productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing a cutting state of an inner wall of a steel pipe by a cutting device of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic side view showing the entire processing equipment including the cutting device of the present invention.

FIG. 4 is a schematic diagram for explaining the movement of each of three movable shoes held by a common operating oil pressure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boring bar 2 Boring head 2a Hydraulic oil chamber 2b Bore 3 Hydraulic piping 4 Movable shoe 4a Coil spring 5 Tool 6 Rolling pad 7 Piston 8 Housing 9 Guide roller

Continuation of front page (56) References JP-A-2-139108 (JP, A) JP-A-59-219104 (JP, A) JP-A-4-38305 (JP, U) (58) Fields investigated (Int .Cl. ⁷ , DB name) B23B 29/034 B23B 5/08 B23B 41/00

Claims (1)

(57) [Claims] 1. A rotary driving device for holding one end of a pipe and rotating the pipe about its axis, a boring bar capable of moving back and forth in the axial direction of the pipe, and a boring bar attached to the tip of the boring bar and inserted into the pipe. A copying machine having an insertable boring head, wherein the boring head comprises:
At least three movable shoes movable toward the inner wall of the pipe are provided, and a hydraulic oil chamber for applying a hydraulic pressure to the movable shoes is provided inside the boring head, and a peripheral surface of the movable shoes is provided. A cutting tool for cutting the inner wall of the pipe, and a rolling element having a peripheral surface located closer to the center side than a cutting surface formed by the cutting tool and rolling the inner wall of the pipe in a circumferential direction. A piston having an axial end face is provided, and elastic means for urging the piston toward the hydraulic oil chamber is provided, and the piston is used as a buffer when the pressure of hydraulic oil in the hydraulic oil chamber fluctuates. A profile cutting device for the inner wall of a pipe, characterized by the following.