JP2001310205A - Boring tool with pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To work a hole excellent in straightness, roundness and flatness even in high speed and high feed working by improving performance of a boring tool with a guide pad of small diametrical specifications. SOLUTION: A pad to be installed on a body part 2 and an angular groove 10 of an outer periphery of the body part is formed of cemented carbide higher in rigidity than steel, etc. Additionally, rigidity of the body part is improved from the point of a shape by installing a rear part made thicker than the head end side by fitting it in a flange 4 by making the body part 2 in a stepped shape. It is possible to make a tool hard to vibrate when a cutting edge chip 9 is installed on a head end piece by connecting the head end piece 7 formed of steel of hardness lower than the body part 2, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boring tool with a pad provided with a pad (guide pad) effective for preventing the tool from oscillating around the body of a tool body.

[0002]

2. Description of the Related Art Steel is the main body material of a boring tool. This is because steel has advantages such as low raw material cost, easy machining, and adjustment of the properties of the main body by heat treatment.

[0003] However, the tool body made of steel tends to bend when the value obtained by dividing the total length of the body portion by the diameter of the body portion (hereinafter referred to as L / D value) becomes large, and when the tool is turned sideways, the cutting edge at the tip end. Processing is performed in a state in which hangs down. For this reason, the cutting edge swings (dances), and vibration occurs during the cutting, making it difficult to secure the expected machining surface accuracy.

As a measure for preventing the vibration, in a boring tool having no pad, a structure in which a cemented carbide part (shaft) is fitted to a shaft center portion of a steel tool body (actually disclosed in Japanese Unexamined Utility Model Publication No. 3-10).
No. 3105) has been considered.

[0005] These techniques are intended to keep the cost as low as possible and to have characteristics close to that of cemented carbide while taking advantage of the advantages of the steel body. This is the technology that makes the cemented carbide parts a subordinate.

[0006] On the other hand, a boring tool with a pad makes the pad come into contact with the hole surface machined by the cutting edge at the tip, so that the boring tool with a pad has a higher anti-sway effect than a boring tool without a pad. For this reason, regarding the boring tool with a pad, the material of the tool main body, the L / D value, the shape of the main body in consideration of the bending, and the like are considered, and nothing is mentioned.

Further, there is no actual example in which the body is formed of a highly rigid cemented carbide or the like, and a pad made of a cemented carbide or the like is attached to the body.

[0008]

SUMMARY OF THE INVENTION A boring tool is
The flange part at the back of the main body is attached to the main shaft of the machine, and the head part for drilling is used without being held. Therefore, when the tool is turned sideways, the tip side hangs down like a fishing rod.
This tendency is also observed in steel tool bodies that are currently in the mainstream, and the cutting edge at the tip of the body part is in a state of being easy to dance. As the L / D value increases, the tip droop increases, and the tendency of the cutting edge to dance appears remarkably.

In order to minimize this phenomenon, a method has been adopted in which the rigidity of the steel tool body is increased by heat treatment, but this method cannot provide a satisfactory effect. Also,
The time involved in the heat treatment also causes a delay in the delivery of the tool.

Accordingly, today's padded boring is intended to improve the rigidity of the tool body by heat treatment and to improve the straightness by the self-guide effect of the pad by attaching a cemented carbide pad to the outer periphery of the steel tool body. Tools.

However, even when the boring tool with a pad is used under high-speed rotation and high-feed cutting conditions, inadequate performance such as instability in straightness of a hole formed in a work is observed. Is done.

The present invention is based on the finding that the tool performance is inferior despite having a pad, because the cause is in the tool main body. It aims to provide a boring tool. (1) Maximize the rigidity of the tool body to minimize deflection. (2) Maintain the characteristics of the tool body at all times. (3) Good straightness is obtained even if the L / D value is large with the small diameter tool specification. (4) The tool body is less likely to vibrate and high-precision holes can be machined.

[0013]

In order to solve the above-mentioned problems, according to the present invention, a plurality of tools extending parallel to the axis of the tool are provided on the outer periphery of the body of the tool body extending from the flange for attachment to the main shaft of the machine. In a boring tool in which a square groove is provided and a pad that is in contact with a hole surface processed by a cutting edge at the tip of the body portion is attached to the square groove, the body portion and the pad are
It was formed of a cemented carbide or a material having a rigidity equal to or higher than that of the cemented carbide.

In this tool, the outer diameter of the rear portion of the body is made 4 to 20 mm thicker than the outer diameter of the portion to which the pad is attached.
It is preferable that a step formed on the outer periphery of the body portion is connected by a radius or a taper, and a rear portion of the body portion having a large diameter is fitted and attached to the flange. In this configuration, the dimensions of the body are
This is particularly effective when the diameter is 30 mm or less and the L / D value is 6 or more.

It is also preferable that a tip piece made of a material having a lower hardness than the body is joined to the tip of the body, and a cutting edge tip is attached to the tip. It is more preferable that the tip piece and the body are joined by being fitted into and recessed.

[0016]

According to the tool of the present invention, since the body is formed of a material having high rigidity, the tool hardly bends. For example, in the case of using a cemented carbide, which is a sintered alloy, the amount of deflection can be suppressed to about 1/3 as compared with a tool using a steel body.

Further, when the body is formed of a highly rigid cemented carbide or the like, deformation of the tool main body over time due to internal stress is unlikely to occur, and the characteristics of the tool main body can be always maintained constant.

Further, in the case where the body portion is formed in a stepped shape and the rear portion having a larger diameter than the portion into which the pad is incorporated is fitted to the flange, the fitting accuracy with the flange is improved, and the joining area is increased, so that the joining area is increased. Will be sure. The stepped body, particularly the body in which the steps are connected by a radius or a taper, has a high ability to withstand bending, twisting, and compression, and further improves the rigidity of the tool body.

As a result, the straightness of the tool is improved, and the straightness, roundness, and surface properties of the machined hole are improved by suppressing the cutting edge dance.

A tip piece made of a material having a lower hardness than the body part is joined to the tip of the body part, and a cutting edge tip is attached to this tip piece. Vibration is absorbed by the joint of the pieces and is effectively suppressed from propagating to the body portion behind the tip piece. Even if the deflection on the distal end side is suppressed by using a pad, if the vibration is caused in the middle of the longitudinal direction of the body, the effect appears as a deterioration in processing accuracy. In the structure described here, the vibration of the body is less likely to occur, and the roundness and the surface properties of the processed hole are improved.

It should be noted that, when the tip piece and the body are joined by being fitted into and recessed, the joint area can be increased, the torque transmission can be stabilized, and the strength and reliability of the joint can be increased.

[0022]

1 to 4 show a boring tool with a pad according to an embodiment of the present invention. In the illustrated tool, a pad 3 made of cemented carbide is attached to a body portion 2 made of cemented carbide.

The tool body 1 includes a flange 4 to be attached to a main shaft of the machine. Since the flange 4 is disadvantageous in terms of cost and productivity if it is formed by shaving, a method is adopted in which the flange 4 is processed separately from the body 2 and then integrated. In the illustrated tool, a hole is formed in the center of the flange 4, and the body 2 is attached to the hole by shrink fitting. The body 2 of the illustrated tool has a total length L = 530 mm, a diameter D = 24 mm, and an L / D value of 22.

The appearance of the body 2 is stepped. The outer diameter D ₁ of the rear part fitted to the flange 4 is 6 mm thicker than the outer diameter D of the part where the pad 2 is to be incorporated.
The step portion having a height of about 3 mm generated on the outer periphery is connected by a radius 5. FIG. 5 shows an example in which the steps are connected by a taper 6, and such a structure may be adopted.

The tip of the body 2 is a steel tip piece 7.
(8 is a joint portion), and a cutting edge tip 9 is attached to the tip piece 7. Further, a square groove 10 extending parallel to the axis of the tool on the outer periphery of the body 2 including the joint 8.
And the pad 3 is attached to the square groove 10. In the illustrated tool, the tip piece 7 is brazed to the rear body made of a cemented carbide and the cutting tip 9 is attached to the tip piece 7. The cutting edge tip can also be incorporated into a body made of cemented carbide formed integrally with an alloy. The latter structure is more advantageous when the joining of the pieces is difficult due to the small diameter of the tool or when it is difficult to obtain a sufficient joining strength.

FIG. 3 shows the joined state of the tip pieces 3. Here, a substantially V-shaped groove 11 having a vertex portion removed and a projection 12 are provided correspondingly on the abutting surfaces of the two, and the projection and the groove are fitted into concave and convex, and the entire area of the closely contacted surface is brazed. I have. When the diameter of the joint portion is 30 mm or less, the fitting structure sets the apex angle α of V between the groove 11 and the projection 12 to 60 ° to 150 °.
, And the illustrated tool has its apex angle α set to 100 °.

The fitting structure of the joint 8 is not limited to the illustrated V-groove fitting. It is also possible to use a combination of a square groove and a projection that fits in the socket, and a socket that has a square or round cross section and a plug that fits in the socket.

The material of the body portion 2 and the pad 3 may be any material as long as the material has a rigidity comparable or superior to that of a cemented carbide. Recently, various sintered alloys and cermets having high toughness have appeared, and these can be used if there is no problem in torsional rigidity.

[0029]

As described above, in the padded boring tool of the present invention, since the body is formed of a cemented carbide having a rigidity superior to steel, the bending of the main body is suppressed to be small, and the cutting caused by the bending is suppressed. Vibration at the time is reduced, and a processed surface excellent in straightness and roundness can be obtained.

Further, in the case where the body portion is formed in a stepped shape and the rear portion which is thicker than the pad mounting portion is fitted to the flange, the connection with the flange is strengthened, the rigidity of the body portion is further increased, and the speed is increased. Also, it can withstand high feed conditions.
At high speeds and high feeds, the torsional force applied to the tool and the compressive force for bending the tool are large, but the L / D value is 20 due to the synergistic effect of improving the rigidity of the material and the rigidity of the shape. Can be used without any problem, and drilling with good straightness and roundness can be performed.

Further, a tip piece made of steel or the like having a lower hardness than the body part is joined to the tip of the body part, and a cutting edge tip is attached to the tip piece. Propagation is suppressed and the body portion is more difficult to vibrate, so that the processing accuracy is further improved.

In addition, the deformation of the body portion with time is eliminated, and the characteristics of the main body are kept constant.

The tool of the present invention having such characteristics can meet the demand for higher speed and higher efficiency of boring, and can contribute to improvement of productivity and quality of work.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a boring tool with a pad according to the present invention.

FIG. 2 is an enlarged view of a main part of the same tool.

FIG. 3 is a view of the tip of the tool as viewed from a position rotated by 90 °.

FIG. 4 is an enlarged cross-sectional view taken along line XX of FIG. 2;

FIG. 5 is a view showing a modified example of a step portion behind a body portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tool main body 2 Body part 3 Pad 4 Flange 5 R 6 Taper 7 Tip piece 8 Joining part 9 Cutting edge chip 10 Square groove 11 Fitting groove 12 Fitting projection

Claims (5)

[Claims] 1. A plurality of square grooves extending parallel to the axis of a tool are provided on the outer periphery of a body portion of a tool body extending from a flange for attachment to a machine main shaft, and a plurality of square grooves are provided on a hole surface formed by a cutting edge at a tip of the body portion. A boring tool having a pad attached to the square groove, wherein the body and the pad are formed of a cemented carbide or a material having a rigidity equal to or higher than that of a cemented carbide. 2. A body in which the rear outside diameter of the body is made larger by 4 to 20 mm than the outside diameter of a portion to which a pad is attached, and a step formed on the outer periphery of the body is connected by a radius or a taper to make the body larger. 2. The boring tool with a pad according to claim 1, wherein a rear portion of the portion is fitted and attached to the flange. 3. The boring tool with a pad according to claim 1, wherein the body portion has a diameter of 30 mm or less and a total length of 180 mm or more. 4. A tip according to claim 1, wherein a tip piece made of a material having a lower hardness than the body is joined to a tip of the body, and a cutting tip is attached to the tip. Boring tool with pad. 5. The boring tool with a pad according to claim 4, wherein the tip piece and the body are joined by being fitted into and recessed.