JPH11814A - Milling cutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce force applied to a cutting edge in the vertical direction in response to a load by absorbing an abrupt load with expansion/shrinkage of an elastic member interposed between a tool and a tool holder in response to a load applied to the tool, and turning the tool in response to the load. SOLUTION: A tool 2 is mounted on a tool holder 10A freely to turn around a center shaft line O' as a center, and an elastic member 8 is interposed between the tool 2 and the tool holder 10A. In this way, since the tool 2 is turned by shrinkage of the elastic member 8 in response to increase of a load when the load of the prescribed value or more is applied to a cutting edge, a load applied vertically to the cutting edge which is one of factor of chipping is reduced, and since increase of the load per unit area applied to the cutting edge is restrained, chipping of an edge tip and abnormal abrasion are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a milling cutter used for a milling machine or a machining center for milling a workpiece.

[0002]

2. Description of the Related Art Conventionally, as this kind of milling machine or milling cutter 10 of a machining center, there is one shown in FIGS. This milling cutter 10
Has a disk-shaped tool holder 10A as shown in FIG. 8, and a mounting hole 5 for mounting the tool 2 is formed in the tool holder 10A. Fixed.

As shown in FIG. 10, a cutting blade 1 is fixed to the tip of the tool 2. As shown in FIG. 7, the milling cutter 10 is attached to a tapered portion at the tip of the spindle 13, and performs milling on the work W by rotation of the spindle 13.

[0004]

In the above conventional technique, an excessive load acting instantaneously on the cutting blade 1 at the time of initial cutting (when the cutting blade 1 comes into contact with the workpiece W) or a load due to mechanical vibration or the like. , There is a problem that chipping and abnormal wear of the cutting blade 1 occur. This problem is particularly likely to occur when the cutting edge 1 cuts into the workpiece W, and is mainly caused by an increase in the load applied to the cutting edge 1 from the vertical direction.

As shown in FIG. 9, the blade length d acting on the cutting blade 1 by the cutting is changed by the angle of the tool holder 10A. If the cutting amount is constant, the blade length d at a predetermined angle is Always constant. Therefore, as shown in FIG. 10, the action surface T acting by the cut becomes constant.
Therefore, the cutting force applied to the cutting blade 1 at each angle always acts on the limited working surface T. Therefore, if the cutting resistance is excessively increased as described above, the load per unit area acting on the working surface T is increased, so that there has been a problem that the above-described chipping, abnormal wear, and the like are likely to occur.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and the invention according to claim 1 has an elastic member interposed between a tool holder and a tool. It is a milling cutter characterized by the following. The invention according to claim 2 is a milling cutter characterized in that the tool is fixed to the tool holder so as to allow only turning, and an elastic member is inserted between the tool and the tool holder.

According to a third aspect of the present invention, a tool is fixed to a tool holder so as to allow only turning, and a fixing member for fixing the tool to the tool holder while allowing only turning is provided. A milling cutter characterized in that an elastic member is interposed therebetween.

[0008]

FIG. 1 shows a first embodiment of the present invention.
This will be described with reference to FIGS. FIG. 7 shows a state where the work W is being milled by the milling cutter 10 of the present invention. A milling cutter 10 is attached to the tip of a spindle 13 that is supported on a headstock (not shown) and is driven to rotate around the center axis.
Is rotated to move from right to left in the figure by a predetermined cutting amount, thereby performing the milling of the work W.

FIG. 1 is an enlarged plan view of the milling cutter 10. The milling cutter 10 includes a tool 2 and a tool holder 10A that holds the tool 2. In the present embodiment, as shown in FIG. 2, the tool 2 has a semicircular cross section of the upper mounting portion, and the lower end and the right end thereof are offset from the center axis O ′ of the semicircular mounting portion. The cutting blade 1 is fixed to the position where it was set.

With this configuration, when a cutting resistance (load) of a predetermined value or more is applied to the cutting edge 1, the tool 2 is moved to the center axis O '.
You can turn around. The shape of this tool is not limited to the shape shown in FIG.
Any shape may be used as long as the tool 2 can turn around its central axis O 'when the cutting force exceeds a predetermined value. Returning to FIG. 1, the tool holder 10A is provided with a plurality of circular mounting holes 5 for mounting the tool 2 (four in the present embodiment). The tool 2 is attached to the mounting hole 5
Notch 1 formed in the tool holder 10A
1 is fixed to the tool holder 10A by screwing the large diameter screw 3A. Reference numeral 12 denotes a spindle mounting hole for receiving the tapered end of the spindle 13.

In the first embodiment, the large-diameter screw 3A has a double structure, as shown in an enlarged view below FIG. A screw groove 6 is cut inside, and a small-diameter screw 3B having a sharp tip is screwed into the screw groove 6. The tool 2 having a semicircular cross-sectional shape is pressed against the semicircular portion below the mounting hole 5 by the small-diameter screw 3B, so that only the turning around the central axis O ′ is permitted, and the vertical and horizontal directions and the front and rear directions of the drawing move. Is regulated and fixed. To prevent the tool 2 from jumping out, a cover plate 15 is fixed to the tool holder 10A so as to cover the mounting hole 5.

An elastic member 8 such as a nylon resin is interposed between the large diameter screw 3A and the tool 2. Therefore, the turning of the tool 2 around the central axis O ′ is restricted within the range of the elastic force of the elastic member 8 by the tightening degree of the large-diameter screw 3A. For example, as shown in FIG. 3, there is a type (1) in which the elastic member 8 is annularly fixed or fitted to the distal end of the large-diameter screw 3A. Further, the present invention is not limited to this mode, and may be an arc shape (2) or a rectangular shape (3). That is, when the tool 2 turns around the O ′ axis due to the cutting resistance in the operation described below, it is sufficient that the tool 2 is disposed at a position where the cutting resistance can be received.

The elastic member 8 is not limited to nylon resin, but may be vinyl chloride, polyester, FRP, or the like, as shown in FIG. However, tool holder 10A
A material having an elastic coefficient smaller than the elastic coefficient of The operation of the first embodiment will be described below. The milling cutter 10 is rotated by the rotation of the main shaft 13, and FIG.
The workpiece W is milled as shown in FIG. On this occasion,
FIG. 6 shows an operation surface T acting on cutting of the cutting blade 1 at a certain angular position of the tool holder 10A.

If the cutting resistance exceeds a predetermined value at the start of cutting or during cutting, the tool 2 turns around the central axis O 'against the elastic force of the elastic member 8 and escapes, thereby causing chipping and abnormal wear. An excessive load is prevented from being exerted on the working surface T. FIG. 4 is a simplified view of the front flank of the lower portion of the cutting edge 1 when the tool 2 cuts into the workpiece W when viewed from above. The broken line TYPE 1 is a conventional non-rotating type, and the solid line TYPE 2 Is a swiveling type of the present invention.

In the TYPE 1, the cutting blade 1 cuts the work W vertically at the time of biting, so that the load F is directly applied to the cutting blade 1 vertically, which is a factor that easily causes chipping. However, in the TYPE 2 of the present invention, since the tool 2 is turned by α degrees according to the load F, when the load F is disassembled into Fx and Fy components, the force applied to the cutting edge 1 in the vertical direction, which causes chipping, becomes Fx.
That is, assuming that the tool 2 has turned by α degrees according to the load F, the vertical component Fx is reduced to Fx = FCOSα.

When the cutting edge 1 is located behind the turning center O 'of the tool 2 as shown in FIGS. 2B and 2C,
As shown in FIG. 4, the turning of the tool 2 causes the cutting edge to retreat very slightly by ε, but the locus L2 of the cutting edge at this time converges to a normal unturned locus L1 with a decrease in load. Further, if the cutting blade 1 is fixed in front of the tool center O ', the length of the cutting blade is increased. At this time, similarly, it converges on the locus L as the load decreases.

Here, at the time of "bite-in", the load always increases, so that the cutting blade 1 always starts cutting in a state of turning by α degrees. Therefore, if the cutting depth is A, the blade length acting on the cutting was conventionally always d, but in the case of the present invention, the blade length becomes d 'except for the retraction of ε at the time of the initial cutting, and the blade length is d' become longer. This also reduces the load on the cutting blade 1. This will be described below together with the operation of turning in the middle of cutting in FIG.

FIG. 5 shows the state of the cutting blade 1 during cutting when the tool 2 of FIG. 2A is used. TYPE1
(Dashed line) shows the state of the cutting edge 1 of the conventional milling cutter that does not turn, TYPE2 (two-dot chain line) shows that the milling cutter of the present invention applies an excessive load to the cutting edge 1 and turns α degrees,
YPE2 '(solid line) shows a state in which the turned cutting edge 1 is located at the conventional angular position for comparison with the conventional one.

The state of the cutting edge of the conventional cutting blade 1 shown by TYPE 1 (broken line) is cut at a substantially right angle (the rake angle is 0) with respect to the work W as described above, and acts on the cutting of the cutting blade 1. The blade length was d.
The angle of the 2 ′ (solid line) cutting blade 1 is α ′ degrees (the rake angle is minus) at the same angular position as in the related art, and the blade length acting on this cutting is d ′.

That is, d ′ = (1 / COSα ′) d, and the turning length of the cutting blade 1 increases by 1 / COSα ′ by turning. In addition, as shown in FIG. 6, the turning surface of the tool 2 enlarges the operation surface T that is applied to the cutting by T ′. Therefore, the working surface T is increased with an increase in the cutting resistance, so that the load per unit area is reduced. Further, since the cutting blade 1 turns in a direction in which the cutting blade 1 escapes (the rake angle is a minus direction) in accordance with an increase in the load, the load acting on the cutting blade 1 is automatically suppressed. With these, the occurrence of chipping or the like can be suppressed.

At this time, as described above, if the cutting blade 1 is located after the turning center O 'of the tool 2 (for example, FIGS. 2B and 2C), the blade length is reduced (for ε in FIG. 4). The cutting edge 1 is located forward of the tool turning center O '.
Is preferably fixed (for example, FIG. 2A). At this time, the load applied from the work W to the tip of the blade edge is increased, but this increase in the load is very small, and has no effect.

In the above embodiment, the tool 2
Pivots around its central axis O ′ to cope with load fluctuations due to cutting resistance, but the present invention is not limited to this embodiment. For example, in the second embodiment shown in FIG. 11, the rotation center O of the tool holder 10A is
The tool 2 and the elastic member 8 are disposed in the mounting hole 5, and the pressing member 3C
The tool 2 is fixed by pressing the elastic member 8 with the screw 3 screwed from the notch 11 through the hole. Cutting resistance F
Increases more than the elastic force of the elastic member 8, the tool 2 retreats along the fan-shaped mounting hole in the direction opposite to the rotation direction of the tool holder 10A against the elastic force of the elastic member 8, thereby causing the cutting blade 1 to It absorbs the excessive load applied.

As a third embodiment, the fan-shaped mounting hole 5 shown in FIG. 11 is designed so that the tool 2 escapes when a load greater than a predetermined value acts on the cutting blade 1. May be inclined. The fourth embodiment shown in FIG. 12 is an extension of the third embodiment described above. An adjusting member 23 is provided on a tool holder 10A so as to be pivotable about a pivot pin 22. This is a configuration in which the tool 2 is mounted by providing the above-described fan-shaped mounting hole 5 in the adjustment member 23. The adjusting member 23 is turned around a center axis O2 shifted from the turning center axis O1 of the tool holder 10A, and can be positioned at a predetermined angular position by the elongated holes 21 and the bolts 20 provided in the tool holder 10A. Therefore,
Since the angle of the mounting hole 5 is arbitrarily determined within the range of the elongated hole 21, the value of the rake angle in the radial direction (the cutting angle of the cutting blade with respect to the workpiece) can be arbitrarily changed, and the apparatus can cope with all cutting conditions. be able to.

[0024]

According to the milling cutter of the present invention, the elastic member interposed between the tool and the tool holder expands and contracts according to the load acting on the tool to absorb a sudden load.
By turning the tool according to the load, the force applied to the cutting edge in the vertical direction can be reduced according to the load.
Also, the blade length d of the cutting blade acting on the cutting in accordance with the increase in the load
Further, since the working surface T is increased, an increase in load per unit area applied to the cutting blade can be suppressed. Therefore, occurrence of chipping and abnormal wear can be suppressed, and the life of the tool can be extended. Further, the rake angle in the radial direction can be arbitrarily set according to the cutting conditions.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a milling cutter according to a first embodiment of the present invention.

FIG. 2 is a view showing a tool 2;

FIG. 3 is a diagram showing a large-diameter screw.

FIG. 4 is a simplified diagram showing a change in a front flank surface of a cutting edge when biting.

FIG. 5 is a simplified diagram showing a change in a front flank of a cutting edge during cutting.

FIG. 6 is an enlarged view of a tool tip in the present invention.

FIG. 7 is a schematic diagram showing a state of milling by a milling cutter.

FIG. 8 is a diagram showing a conventional milling cutter.

FIG. 9 is a simplified diagram showing a change in blade length acting on a cutting blade.

FIG. 10 is an enlarged view of a tool tip in a conventional technique.

FIG. 11 is a partially enlarged cross-sectional view illustrating a mounting hole according to a second embodiment.

FIG. 12 is a partially enlarged sectional view illustrating a mounting hole according to a fourth embodiment.

FIG. 13 is a table showing a part of materials of an elastic body and a tool holder.

[Explanation of symbols]

 Reference Signs List 1 cutting edge 2 tool 3 screw 3A large diameter screw 3B small diameter screw 3C pressing member 5 mounting hole 6 screw groove 8 elastic member 10 milling cutter 10A tool holder 11 notch 12 main shaft mounting hole 13 main shaft 15 cover plate 20 bolt 21 long hole 22 Pivot pin 23 Adjusting member d (d ') Cutting blade length O' Tool turning center axis O1 Tool holder turning center axis O2 Turning center axis of adjusting member T (T ') Working surface

Claims (3)

[Claims] 1. A milling cutter for milling a workpiece, comprising: a tool holder attached to a tip of a rotating spindle; and a tool fixed to the tool holder and having a cutting blade for cutting the workpiece at the tip. A milling cutter comprising an elastic member interposed between the tool holder and the tool. 2. A milling cutter for milling a workpiece, comprising: a tool holder attached to a tip of a rotating main spindle; and a tool fixed to the tool holder and having a cutting edge for cutting the workpiece at the tip. A milling cutter, wherein the tool is fixed to the tool holder so as to allow only turning, and an elastic member is interposed between the tool and the tool holder. 3. A milling cutter for milling a workpiece, comprising: a tool holder attached to a tip of a rotating main spindle; and a tool fixed to the tool holder and having a cutting edge for cutting the workpiece at the tip. The tool is fixed to the tool holder so as to allow only turning, and a fixing member is provided to fix the tool to the tool holder while allowing only the turning, and an elastic member is interposed between the fixing member and the tool. A milling cutter characterized by the following.