JPH0655303A - Cutting tool for chamfering circular machining - Google Patents

Abstract

PURPOSE:To enable chamfering surely simply by providing a swivel range set mechanism on a cutting tool holding arm to set a holding arm swivel range according to a machining hole inner diameter and also setting the vertical movement range of a tool according to the thickness of a work. CONSTITUTION:A cutting tool holding arm 4 in which a chamfering cutting tool 3 is fixed detachably on the surface opposite to a shank mounting surface for a disk member 2 that is fixed co-axially with a shank 1 at the tip of it is enabled to swivel on a surface parallel to the disk member 2 with its base mounted on a shaft at an eccentric position. A swivel range set mechanism (9 and 10) is attached to the cutting tool holding arm 4, and the cutting tool 3 on the cutting tool holding arm 4 which is displaced according to swiveling of the cutting tool supporting arm 4 is enabled to displace only at a specified area on the outside of the edge of the disk member 2. Also a spring 12 to energize the arm 4 in the direction that the cutting tool 3 is separated from the center of the disk member 2 is mounted on the arm 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a "burr" generated at the edge of a hole when a circular hole is formed in a plate material by cutting.
The present invention relates to a cutting tool for chamfering, for removing the.

[0002]

2. Description of the Related Art In cutting a metal material with a machine tool, a lathe has been mainly used to cut a circular hole.
Milling machines and shapers have been used for flat and square machining, but in recent years, with the progress of electronic control technology, machining centers that perform many types of machining while exchanging many cutting tools themselves according to computer programs The so-called machine tool emerged, and it became possible to perform multiple types of machining with a single machine.

However, there are still some processes that are difficult to process by a machining center, one of which is
There is chamfering of circular holes.

Chamfering was a relatively easy task in the conventional machining with a lathe because the blade was manually fed at low speed while rotating the workpiece, but in machining with a machining center the workpiece did not rotate and the cutting tool was used. Since the machine rotates, the chamfering amount varies if the thickness of the processed product is uneven, so it is not so easy as when using a lathe. In particular, when the chamfering target is a large-diameter hole, there is no suitable cutting tool for use in the machining center. For this reason, the chamfering process may be an obstacle to the fully-automatic machining which is the original purpose of using the machining center.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a cutting tool suitable for chamfering a large diameter hole by a machining center.

[0006]

[Means for Solving the Problems] A cutting blade supporting arm having a cutting blade for chamfering removably attached to a surface of a disk-shaped member fixed to the shank tip coaxially with the shank on the side opposite to the shank mounting surface (hereinafter , A supporting arm) is pivotally mounted at its base at an eccentric position so as to be rotatable in a plane parallel to the disc-shaped member,
A cutting range setting mechanism is attached so that the cutting blade on the support arm, which is displaced as the supporting arm rotates, can be displaced only in a predetermined region outside the edge of the disk-shaped member, and the cutting blade is also made into a disk-shaped member. A spring for biasing the support arm in the direction away from the center of the was attached to the support arm.

In this tool, a square throw-away tip is used as a cutting tool, one of its diagonal lines is made parallel to the central axis of the tool, and the other diagonal line is perpendicular to the central axis of the tool. Attach to the support arm in a facing orientation. In this state, the two sides that sandwich the corner of the throw-away tip facing outward are 45 ° with respect to the horizontal.
It is attached to the machining center in a tilted state and acts as a cutting blade. The corners sandwiched by the above two sides are rounded so that the cutting ability is lost.

[0008]

When chamfering a circular machining hole using the cutting tool of the present invention, first, the turning range setting mechanism is adjusted according to the diameter of the circular machining hole formed in the workpiece to adjust the support arm. Select the turning range. That is, when the radius of the machining hole is R, the turning range of the support arm is adjusted so that the position of the cutting tool satisfies the following condition. a <R <b b ′ <R, where a: distance between the downward corner of the cutting tool and the tool center axis (however, the value when the spring acting on the support arm is fully extended) b: cutting tool Distance between the rounded corner and the tool center axis (however, the value when the spring acting on the support arm is fully extended) b ′: Cutting tool by turning the support arm against the force of the spring The distance between the rounded corner of the cutting tool and the tool center axis when the tool is closest to the tool center axis.

After the turning range of the support arm is adjusted as described above, when this tool is attached to the machining center with the shank portion and is rotated and machined toward the workpiece fixed in the coaxial arrangement, there is a burr circular machining. The lower cutting edge contacts the edge of the hole at an angle of 45 ° to the vertical.
For this reason. When the machining center further pushes the tool down, cutting is performed by the cutting blade.

During cutting, a force acting in the direction of the tool center axis acts on the cutting blade as a reaction. This force is transmitted to the support arm, and the support arm is rotated against the force of the spring to try to displace the cutting blade in the tool central axis direction. Therefore, if the processing speed of the tool is appropriately selected according to the chamfering cutting speed, the cutting tool is moved in the direction of the tool center axis until the cutting tool comes into contact with the edge of the circular hole at the rounded corner. It is possible to perform the chamfering cutting while performing appropriate chamfering cutting. When the cutting edge comes into contact with the edge of the rounded corner hole, the cutting is stopped, and the cutting edge is processed while sliding on the wall surface of the round hole at the rounded corner. When the above-mentioned corner of the cutting tool reaches the lower opening of the processing hole and goes out further below,
This time, the cutting blade on the upper side of the corner comes into contact with the edge of the processing hole at an angle of 45 ° with respect to the vertical, and the lower opening is chamfered.

[0011]

The present invention will be described below with reference to examples.

The basic layout of the main parts of this tool is shown in FIG.
The support arm 4 of the cutting blade 3 is pivotally mounted by a bolt 5 on the surface opposite to the mounting surface (lower side in FIG. 1).

Referring to FIG. 2 which is a bottom view, the support arm 4 and its related mechanism will be described in detail. The mounting bolt 5 of the support arm 4 is located away from the center of the disk-shaped member 2 and near the edge thereof. The support arm 4 is curved in an arc shape, and the cutting blade 3 is attached by a screw 6 at a position near the tip thereof.

At the tip of the support arm 4, one end of a rod 7, which is a component of a mechanism for setting the turning range, is attached.
They are connected by a pin 8. The rod 7 is loosely inserted in the cylindrical member 9, but the clip-shaped stopper 10 is fixed to the opposite end 7a protruding from the cylindrical member 9 so that the rod 7 does not slip out toward the support arm 4. The inner diameter of the cylindrical member 9 is slightly enlarged in about a half portion facing the support arm 4, and the spring 12 is arranged coaxially with the rod 7 between the shoulder-shaped portion 11 and the support arm 4 whose inner diameter is enlarged. Has been inserted. The spring 12 tries to separate the support arm 4 and the cylindrical member 9 from each other until the stopper 10 of the rod 7 connected to the support arm 4 contacts the end of the cylindrical member 9 in FIG.

The cylindrical member 9 is provided with a support 13 for fixing its position on the disk-shaped member 2 and a bolt 14.
It is fixed by. The support 13 is generally U-shaped as shown in FIG.
By inserting the cylindrical member 9 through 5 and tightening the screw 14 in the screw hole 16, the cylindrical member 9 can be fixed at an arbitrary position on the outer circumference.

A bolt insertion hole 17 is formed in the support 13 on the side opposite to the screw hole 16 with the tunnel-shaped portion 15 interposed therebetween. A bolt 20 is inserted into the bush 18 after the bush 18 is fitted therein. The bolt 20 has an arc-shaped groove 19 and a T-shaped cross-section formed in the disk-shaped member 2 in advance.
The head portion 20a is fitted in and is slidable along the groove 19, but cannot be separated from the disc-shaped member 2. When the nut 21 is fitted and tightened at the tip of the bolt 20, the bolt 20 also becomes non-slippery, so that the support 13 can be fixed to the disc-shaped member 2. However, since the bush 18 is fitted in the bolt insertion hole 17, the support tool 13 fixed only by the bolt 20 can rotate about the bolt 20 as a spindle.

As described above, the fixing position of the support 13 and the cylindrical member 9 supported by the support 13 can be changed within a certain range by selecting the position of the bolt 20 on the groove 19 when tightening the nut 21.

Cutting blade 3 attached to the support arm 4
Is a square throw-away tip with one side of about 12 mm, and as is clear from FIGS. 1 and 2, the diagonal is parallel to the central axis of one tool, and the other diagonal is the central axis of the tool. It is attached to the support arm 4 so as to be oriented in a direction orthogonal to Therefore, of the two blades sandwiching the corner 22, the upper blade 23 is inclined 45 ° with respect to the horizontal and the lower blade is inclined −45 °. Note that the corner portion 22 is rounded by the handler hand as shown in an enlarged view in FIG. 4, and is in a state without cutting ability.

Since the tip end of the support arm 4 of this tool is connected to the above-mentioned mechanism, the turning angle is limited to a certain range, and the turning area is variable. That is, when the position of the bolt 20 on the groove 19 is determined and the positions of the support 13 and the cylindrical member 9 are also determined accordingly, the support arm 4 pushed by the spring 12 is pressed.
Is determined, and it is one of the limit positions of the swing region of the support arm 4.

Then, the support arm 4 compresses the spring 12 when a force of a certain magnitude or more acts to rotate the support arm 4 in the clockwise direction in FIG.
It is possible to turn to the compression limit of. During this turning, the rod 7 connected by the pin 8 advances into the cylindrical member 9. The support tool 13, which receives the force from the support arm 4 via the spring 12 and the rod 7, changes the central axes of the cylindrical member 9 and the rod 7 by slightly rotating around the bolt 20 to support it. The arm 4 can be smoothly turned.

As the fixing position of the support 13 by the bolt 20 shifts to the right on the groove 19 in FIG. 2, the pivot region of the support arm 4 becomes closer to the central axis of the tool, and when the tool is rotated accordingly. The radius of gyration of the cutting blade 3 on the support arm 4 becomes smaller.

Chamfering of a circular machining hole using this cutting tool will be described with reference to FIG. First, the turning position of the support arm 4 is adjusted by the above method so that the position of the cutting tool 3 on the support arm 4 satisfies the following condition. a <R <b b ′ <R, where R is the radius of the circular machining hole, a is the distance between the downwardly oriented portions 3 a of the cutting tool 3 and the tool center axis c (however, the spring 1 acting on the support arm 4
2 is the value when fully extended) b: The distance between the rounded corner 22 of the cutting tool 3 and the tool center axis) (however, the value when the spring 12 acting on the support arm 4 is fully extended) b ′: the rounded corner portion 22 of the cutting tool 3 and the tool center when the cutting tool 3 is brought closest to the center axis c of the tool by pivoting the support arm 4 against the force of the spring 12. Distance to axis c.

After that, this tool is attached to the machining center with the shank 1 portion, and while being rotated, the machined hole 2
5 is arranged coaxially with the tool and processed toward the fixed work piece 26. The cutting blade 3 is to be machined while making a turning motion on the circumference of the edge having a radius of approximately R. Then, first, the lower cutting blade 24 comes into contact with the edge portion 27 of the circular processed hole 25 having a burr at an angle of 45 ° with respect to the vertical direction (FIG. 5A).
State).

When the machining center further pushes the tool down, the turning cutting blade 24 chamfers the chamfered portion 30. During the cutting, a force in the tool center axis direction acts on the cutting blade 3 as a reaction of the pushing down force. This force is transmitted to the support arm 4 and the spring 1
The support arm 4 is swung inward against the force of 2 to displace the cutting blade 3 in the tool central axis direction. For this reason, if the machining speed of the tool is appropriately selected according to the chamfering cutting speed, the cutting blade 3 is cut until the cutting edge 3 comes into contact with the edge 27 of the circular processing hole 25 at the rounded corner 22. Can be displaced to the center axis of the tool, and an appropriate chamfering cutting can be performed therebetween. Cutting edge 3
When the rounded corner portion 22 comes into contact with the edge of the drilled hole 25, the chamfering cutting is completed, and then the cutting blade 3 is worked while sliding the wall surface 25a of the drilled hole 25 at the rounded corner portion 22. (State of FIG. 5B).

When the corner 22 of the cutting tool 3 reaches the edge 28 of the lower opening of the processing hole 25 and further comes out to the lower side to be in the state shown in FIG. C, the cutting blade 23 above the corner 22 becomes vertical. To 4
It begins to swivel while contacting the edge 28 at an angle of 5 ° and the chamfer 30 of the lower opening begins. The chamfering is completed in the same way as the upper opening, and the cutting blade 3 is completely processed 2
When it comes out to the lower side of 6, the support arm 4 returns to the original position by the restoring force of the spring 12. After that, when the tool is raised at a rapid speed, the cutting blade 3 in contact with the machining hole 25 causes the support arm 4 to swivel in the opposite direction to that in the above-described machining stroke, but the additional rising speed is added. With almost no chamfering cutting, the state before the chamfering cutting was started is restored.

In order to reliably and efficiently perform the appropriate chamfering cutting as described above, it is necessary to properly select the spring constant of the spring 12 for preventing the support arm 4 from turning inwardly when the tool is pushed down. is necessary. Spring 12
What is the effect of? Fine adjustment can be performed by shifting the position at which the support shaft 13 holds and fixes the cylindrical member 9.

[0026]

The present invention is as follows. Based on the configuration as described above, the following effects are obtained. 1) When chamfering with a conventional chamfering cutting tool by a machining center, the work of determining the coordinates of the feed end of the cutting tool is extremely complicated, and many test processes are required. In particular, if the thickness accuracy of the processed product is poor, it is difficult and even manual work is unavoidable, which has been an obstacle to fully automatic processing. According to the present invention, this problem is solved all at once, and the chamfering is surely performed only by setting the support arm turning region according to the inner diameter of the processing hole and setting the vertical movement range of the tool according to the thickness of the processed product. You can 2) By adjusting the turning area of the support arm, one tool can be used to chamfer machined holes of various inner diameters, so that the number of tools to be prepared can be small. 3) By making the disk-shaped member large in diameter, it is possible to manufacture a hole that can be used for any large-diameter machined hole. 4) It is possible to easily perform chamfering of the back surface, which is difficult with the conventional chamfering cutting tool. 5) It is possible to easily adjust the chamfering cutting amount by adjusting the tool axial feed speed (sometimes by temporarily stopping the feed). Therefore, it is easy to change the chamfer size on the front surface and the back surface. 6) Since a general-purpose throw-away tip, which is inexpensive and easy to obtain, is used for the cutting blade, the cutting edge can be easily updated and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a front view and B is a bottom view showing essential parts of an embodiment of the present invention.

FIG. 2 is a front view of a support tool 13.

FIG. 3 is an enlarged view of the tip of the cutting blade 3.

FIG. 4 is an explanatory diagram of a chamfering cutting process.

[Explanation of symbols]

 1 Shank 2 Disc-shaped member 3 Cutting blade 4 Support arm 7 Rod 8 Pin 9 Cylindrical member 12 Spring 13 Support tool 19 Groove

Claims (2)

[Claims] 1. A cutting tool support arm, to which a chamfering cutting tool is detachably fixed, is provided at an eccentric position on a surface of a disk-shaped member fixed to the shank tip in a coaxial arrangement with the shank, opposite to the shank mounting surface. On the cutting tool supporting arm that is pivotally mounted on the cutting tool supporting arm so that it can be swung in a plane parallel to the disk-shaped member, and a turning range setting mechanism is attached to the cutting tool supporting arm to displace with the turning of the cutting tool supporting arm. A cutting blade supporting arm is provided with a spring that allows the cutting blade to be displaced only in a predetermined area outside the edge of the disk-shaped member, and biases the cutting blade supporting arm in a direction away from the center of the disk-shaped member. A circular cutting hole chamfering cutting tool that is attached to the. 2. The cutting tool according to claim 1, wherein a throw-away tip is used as the cutting tool.