JP7577324B2 - Pipe inner surface cutting tool - Google Patents

Description

The present invention relates to a cutting tool for cutting the inner surface of metal tubes such as steel pipes, pipes, and cylinders, and relates to a cutting tool for the inner surface of a tube that can cut the inner surface of a metal tube evenly even if there is a misalignment between the center of the metal tube and the center of rotation of the processing tool.

The inner surface of metal pipes is covered with an oxide film called black scale that occurs during pipe manufacturing. When the surface is rough and dimensional accuracy is required, this oxide film is smoothed by cutting (a process known as skiving) or blasting.

The machining tools disclosed in Patent Documents 1 and 2 are known as techniques for cutting the inner surface of a metal tube with high precision. These machining tools perform cutting by pressing a cartridge equipped with a cutting blade tip against the metal tube in the radial direction. The machining tool in Patent Document 1 is configured such that a rod attached to the axis of the machining tool is moved back and forth, so that when the machining tool enters the metal tube, the cartridge is pushed out in the system direction, and when the machining tool retreats, it is retracted.

Also, according to Patent Document 2, a tool for roller burnishing is attached behind the cutting tool that performs the rough cutting and floating cutting processes, and cutting is performed when entering the metal pipe, and a burnishing roller is rolled out to roll down the cut surface when retreating.

Roller burnishing is a processing method in which the cutting surface is pressed with a roller to plastically deform it and produce a smooth finish.

Japanese Utility Model Application Publication No. 1-101708 Japanese Patent Application Publication No. 6-39607

In the techniques of Patent Documents 1 and 2, a cartridge equipped with a cutting blade is arranged to abut radially against a drive shaft arranged at the center of rotation of the processing tool. In the technique of Patent Document 1, a tapered portion is formed at the front end of the drive shaft (piston rod 12a, Figure 1 of the same publication), and the cartridge rides up on this taper and is pushed out. Due to this structure, if the position of the drive shaft at the axis of the processing tool and the center of the metal tube are misaligned, the inner surface of the metal tube cannot be cut uniformly.

Also, in the technology of Patent Document 2, a pair of cartridges (adapters) are arranged in the diametric direction around the drive shaft (moving axis 14, Figure 1 of the same publication), and a stop bolt is screwed from each cartridge toward the center. The bolt abuts against an inner collar through which the drive shaft passes, and as in Patent Document 1, the position of the cartridge depends on the position of the drive shaft.

The black scale that occurs during pipe manufacturing is a thin oxide film, and with the machining tools of Patent Documents 1 and 2, if the metal tube and drive shaft are misaligned, it is not possible to accurately scrape off the black scale thinly. Such misalignment frequently occurs due to distortion of the metal tube or machining tool, or rotational fluctuation. Therefore, with conventional machining tools, in order to deal with such misalignment, it is necessary to cut thicker than the black scale.

The present invention aims to solve these conventional problems by providing a machining tool that can perform cutting to uniformly remove the inner surface of a metal tube even if the position of the drive shaft and the center of the metal tube are misaligned.

In order to achieve the above object, the cutting tool of the present invention comprises: a rod-shaped base portion having a center hole at a rotation center;
a pair of cartridges, each of which holds a cutting blade for cutting the inner surface of a metal pipe, which are arranged on the same circumference with respect to a rotation center, facing each other across the rotation center, and biased toward the rotation center;
a drive shaft that is movable back and forth within the center hole and has through holes that intersect perpendicularly with an axis of a rotation center in correspondence with the positions of the pair of cartridges;
a linking body that is inserted into the through hole, and is restricted in its movement in the axial direction of the rotation center relative to the through hole , but is slidable in the radial direction relative to the rotation center, and has cam surfaces on both sides of the outer periphery in the radial direction, the distance from the center line changing line-symmetrically with respect to the center line in the radial direction;
The cartridges each have a slider that is in contact with the cam surface.

In the cutting processing device of the present invention, the cartridges facing each other on the diameter of the processing tool are held free in the radial direction from the drive shaft of the processing tool while maintaining the distance between them, so cutting can be performed uniformly even if the position of the drive shaft and the center of the metal tube are misaligned.

FIG. FIG. 2 is a cross-sectional view of a cutting tool. FIG. 13 is a diagram showing the operation of a cutting tool. FIG. 13 is a diagram showing an example of a composite tool in which a burnishing tool is connected to a cutting tool.

The following describes an embodiment of the cutting tool 1 of the present invention with reference to the drawings. Figure 1 is a perspective view of the cutting tool 1. The cutting tool 1 is attached to a spindle (not shown) of a machine tool, and the cutting tool 1 is inserted (in the forward direction F) into the hole of the metal tube with the center of rotation C of the cutting tool 1 aligned with the center of the metal tube. It is rotated around the axis of the spindle's center of rotation, and precision finishing is performed on the inner surface of the metal tube.

The cutting tool 1 comprises a rod-shaped base 2 and a pair of cartridges 4 (only one cartridge is shown in FIG. 1) on the outer periphery of the base 2. The pair of cartridges 4 are arranged on the same circumference with respect to the center of rotation C, facing each other across the center of rotation C, and each cartridge 4 has a cutting blade 5 attached toward the outer periphery. One end of a spring member 6 is fixed to the rear end of the base 2 by a bolt 7. The other end of the spring member 6 biases the cartridge 4 toward the center of rotation C. A pair of guides 8 are provided on the outer periphery of the base 2 rotated 90 degrees around the center of rotation C from the pair of cartridges 4 (only one guide 8 is shown in FIG. 1).

The cutting tool 1 advances the cartridge 4 in the forward direction F toward the inner surface of the metal pipe, which is the workpiece to be cut, and retracts the cartridge 4 in the return direction B to prevent the cutting edge of the cutting blade 5 from hitting the inner surface of the metal pipe.

Figure 2 shows a cross section of the cutting tool 1. A central hole 10 is provided at the center of rotation C of the base part 2, and the drive shaft 3 is inserted into it. The drive shaft 3 moves in the axial direction of the center of rotation C along the central hole 10 by connecting with a driving force imparting mechanism such as a hydraulic cylinder provided in a machine tool (not shown). Figure 2A shows a cross section when the drive shaft 3 moves in the forward direction F (forward), and Figure 2B shows a cross section when the drive shaft moves in the return direction B (reverse). Figures 2C and 2D are perspective views showing the relationship between the drive shaft 3 and a linking body 11, which will be described later.

2C and 2D, the drive shaft 3 has a through hole 13 that intersects perpendicularly with the axial direction of the rotation center C (forward direction F/return direction B). The linking body 11 is inserted into the through hole 13. The linking body 11 is surrounded by the through hole 13, so that its movement in the axial direction of the rotation center C is restricted, while it is slidable in the radial direction R centered on the rotation center C. Both side surfaces of the linking body 11 on the outer periphery in the radial direction R are cam surfaces 11a. The cam surface 11a is a surface whose distance from the center line BC of the linking body 11 in the radial direction R changes when the center line BC of the linking body 11 in the radial direction R is used as a reference. The cam surfaces 11a on both sides are symmetrical with respect to the center line BC. In this example, the front side 11b is a surface parallel to and distant from the center line BC, and the rear side 11d is a surface parallel to and close to the center line BC, and a taper 11c is formed between them to smoothly connect the front side 11b and the rear side 11d. Note that Figures 2C and 2D show the slope of the taper 11c with emphasis.

The base portion 2 also has a communication hole 16 that penetrates the base portion 2 in the radial direction R, and the cartridge 4 is disposed at a position where the communication hole 16 opens upward and downward on the outer periphery of the base portion 2. A slider 12 is provided on the back side (rotation center C side) of the cartridge 4, and abuts against the cam surface 11a of the linking body 11 inside the communication hole 16.

The center hole 10 of the drive shaft 3 is wider at its rear end than the shoulder 2a, and a connecting collar 17 is provided. The connecting collar 17 has a female threaded hole 14a so that it can be connected to a driving force applying mechanism such as a hydraulic cylinder (not shown). The spring 15 in the center hole 10 is provided between the connecting collar 17 and the shoulder 2a of the base part 2, and biases the drive shaft 3 in the return direction B. The base part 2 is also provided with a bearing cap 18 for the drive shaft 3. Further rearward of the center hole 10 of the base part 2 is a female threaded hole 2b so that the cutting tool 1 can be connected to other equipment.

As described above, the cartridge 4 is pressed toward the center of rotation C in the radial direction R by the spring member 6. Therefore, in FIG. 2A, when the drive shaft 3 advances in the forward direction F, the sliders 12 of the upper and lower cartridges 4 abut against the rear side 11d of the lower side of the connecting body 11, and the cutting blades 5 are retracted in the radial direction R in the contracting direction. In FIG. 2B, when the drive shaft retracts in the return direction, the sliders 12 abut against the front side 11b of the higher side of the connecting collar, and the cutting blades 5 protrude in the radial direction. The taper 11c allows the sliders 12 of the cartridges 4 to smoothly transition.

Figures 3A, 3B, and 3C show the action of the linking body 11, and in each figure, the drive shaft 3 retreats in the return direction B, and the cartridge 4 is pushed out in the radial expansion direction. The center PC of the metal tube W and the center of rotation C of the cutting tool may become misaligned due to distortion or vibration of the cutting tool (the misalignment is emphasized in the figures). In order to prevent this misalignment, the base part 2 is provided with a guide 8 (see Figure 1) at the same position as the cartridge 4, but since the guide 8 slides on the inner surface of the metal tube W while the cartridge 4 cuts the inner surface of the tube, the occurrence of misalignment is unavoidable. If misalignment occurs during fine cutting to peel off the black skin on the inner surface of the metal tube W, the black skin will remain in parts.

In Figure 3A, the center PC of the metal tube W and the center of rotation C of the cutting tool 1 are aligned, while in Figures 3B and 3C, they are vertically offset. A linking body 11 is sandwiched between a pair of cartridges 4, and the distance L between the pair of cartridges 4 is determined by the linking body 11. The linking body 11 can also move freely in the radial direction independently of the drive shaft 3, and is not dependent on the position of the center of rotation C of the cutting tool 1. Therefore, the center of the distance L between the pair of cartridges 4, i.e., the center line BC which is the center of the linking body 11, is located at the center PC of the metal tube W, and cutting can be performed at a position that follows the inner surface of the metal tube W.

Figure 4 shows an example of a composite tool in which a burnishing tool 20 that performs roller burnishing is attached to the rear of the cutting tool 1. In this example of the burnishing tool 20, the burnishing roller 21 is stored when entering the metal pipe, and when retreating, the burnishing roller is deployed to roll-press the cutting surface.

The burnishing tool 20 is connected between a driving force applying mechanism (not shown) and the cutting tool 1. The drive shaft 27 that passes through the inside of the tool body 22 has a male screw portion 27a that can be connected to the connecting collar 14 of the drive shaft 3. In addition, the tip of the tool body 22 is provided with a male screw portion 22a that connects to a female screw hole 2b provided in the base portion 2 of the cutting tool 1.

An inner ring 23 is fixed to the outer circumference of the tool body 22. A cylindrical outer race 24 is attached to cover the inner ring 23. The outer race 24 is held by a thrust bearing 25 and a spring 26 so that it can move slightly along the center of rotation C. A number of fitting holes 24a for the burnishing rollers 21 are drilled in parallel at equal pitches on the outer peripheral surface of the outer race 24. The outer circumference of the inner ring 23 is tapered, expanding in diameter in the forward direction F, and the burnishing rollers 21 inserted into the fitting holes 24a of the outer race 24 rollably contact the tapered surface. The burnishing rollers 21 are tapered, contracting in diameter in the forward direction F.

Therefore, when the burnishing tool 20 is moving in the forward direction F, the burnishing roller 21 comes into contact with the inner surface of the metal pipe, and if it encounters resistance, it slides on the reverse tapered surface of the inner ring 23, compressing the spring 26 and reducing the diameter. Next, when moving in the return direction B, it slides on the reverse tapered surface of the inner ring 23 in the direction of expanding the diameter, rolling the inner surface of the pipe.

In this example, a burnishing tool that rolls in the return direction B is connected, but a burnishing tool that expands in diameter when rolling in the forward direction F and contracts in the return direction B (e.g., US Pat. No. 4,367,576, Jan. 11, 1983) may also be connected.

REFERENCE SIGNS LIST 1 Cutting tool 2 Base body 2a Shoulder 2b Female thread hole 3 Drive shaft 4 Cartridge 5 Cutting blade 6 Spring member 7 Bolt 8 Guide 10 Center hole 11 Linking body 11a Cam surface 12 Slider 13 Through hole 14 Connecting collar 14a Female thread hole 15 Spring 16 Communication hole 17 Connecting collar 18 Cap 20 Burnishing tool 21 Burnishing roller 22 Tool body 22a Male thread portion 23 Inner ring 24 Outer race 24a Fitting hole 25 Thrust bearing 26 Spring 27 Drive shaft 27a Male thread portion

Claims (2)

A rod-shaped base portion having a center hole at the center of rotation;
a pair of cartridges, each of which holds a cutting blade for cutting the inner surface of a metal pipe, which are arranged on the same circumference with respect to a rotation center, facing each other across the rotation center, and biased toward the rotation center;
a drive shaft that is movable back and forth within the center hole and has through holes that intersect perpendicularly with an axis of a rotation center in correspondence with the positions of the pair of cartridges;
a linking body that is inserted into the through hole, and is restricted in its movement in the axial direction of the rotation center relative to the through hole , but is slidable in the radial direction relative to the rotation center, and has cam surfaces on both sides of the outer periphery in the radial direction, the distance from the center line changing line-symmetrically with respect to the center line in the radial direction;
a slider provided on each of the pair of cartridges and adapted to come into contact with the cam surface.
2. The cutting tool of claim 1, wherein the cam surface of the linking body has a front side which is a surface parallel to the center line and a rear side which is parallel to the center line and closer to the center line than the front side , and a taper therebetween which smoothly connects the front side and the rear side.