JP2848049B2 - Turning brooch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning broach suitable for cutting a counterweight side of a crankshaft.

[0002]

2. Description of the Related Art In recent years, as a method of cutting a crankshaft of a reciprocating internal combustion engine, a method of continuously performing side cutting of a counterweight, journal width cutting, and journal diameter processing by a turning broach has been widely adopted. FIGS. 7 and 8 show an example of a turning broach used for machining such a crankshaft. A turning broach 1 shown in the drawing has a fan-shaped flat plate-shaped broach body 2 attached to a tool rotation axis S, and a broach body. 2, and a cutting edge tip 4 for journal processing attached to the rear of the cutting edge tip 3 (not shown in FIG. 8). The cutting blade tip 3
Are arranged in a staggered manner such that one ends of the cutting blades 5 alternately protrude to one side in the width direction of the broach main body 2, and each cutting blade 5 is arranged from one circumferential end of the broach main body 2. It is attached so as to gradually protrude toward the outer peripheral side of the broach body 2 toward the other end.

A plurality of turning broaches 1 configured as described above are mounted on the rotating shaft S at an appropriate distance from each other, so that each outer peripheral portion faces the journal J of the crankshaft-shaped work W. Is held. Thereafter, the work W is rotated at a high speed around the axis thereof in a fixed direction (direction of arrow A), and the broach main body 2 is sent out at a low speed toward the distal end side in the circumferential direction (direction of arrow B). As shown, the cutting edge 5 for side surface cutting is the side surface C1, C of the counterweight C of the work W.
2 are cut into a predetermined width. In this case, the cutting edge 5 gradually protrudes toward the outer peripheral side of the broach 1 as it moves toward the rear end side in the circumferential direction of the broach main body 2.
1, C2 is gradually and deeply cut toward the center of the workpiece W in the radial direction. The cutting edge 5b of the cutting edge tip 3b positioned at the rearmost end in the circumferential direction among the cutting edge tips 3
After passing through, the journal J is processed into a predetermined shape by the cutting edge 6 of the cutting edge tip 4 for journal processing described above.

As is apparent from FIG. 9, in the conventional turning broach 1 described above, the amount of projection of the cutting blade 5 for performing side cutting in the width direction of the broach body 2, that is, the center of the broach body 2 in the width direction. The distance x from the line m to the end of the cutting blade 5 protruding outward in the width direction of the broach main body 2 is one cutting blade row E _A protruding to one side in the width direction of the broach main body 2.
Is constant from the cutting edge 5a at the front end in the circumferential direction of the broach 1 to the cutting edge 5b at the rearmost end. Similarly the distance x even another cutting edge row E _B protruding toward the other widthwise side of the broach body 2 is constant, thereby the side C1, C2 is to the center from the outer peripheral end of the counterweight C It is cut to a constant width, that is, flat surfaces parallel to each other. Further, amount of projection of the cutting edge row E _A, the broach radial cutting edge adjacent to the circumferential direction in the E _B (hereinafter, referred to lift.) L also changes from the beginning of the cutting edge 5a of the last The settings are all the same up to the blade 5b.

[0005]

In the conventional turning broach 1 described above, since the amount of projection of each cutting blade 5 in the broach width direction is constant, the cutting attached to the rear end side of the broach body 2 is particularly preferable. There is a disadvantage that the life of the cutting edge of the blade tip 3 is shorter than that of the tip side.

That is, in the cutting by the turning broach 1, since the rotation speed of the broach main body 2 is set to be extremely lower than the rotation speed of the work W, as shown in FIG. The work W rotates several times to several tens of times before the cutting edge 5x of the first member enters between the side surfaces C1 and C2 of the counter weight C and exits to the opposite side. Therefore, by one cutting edge 5x passes between side C1, C2, side C1, C2 is a circular arc R ₁ in contact with the passing track Q of the cutting edge 5x around the rotation center P ₀ of the workpiece W
Will be cut to the position. However, the counterweight of the outer peripheral edge of C up to the circular arc R _1, large arcs R ₀ and lift amount L by the radius of the above than the arc R ₁
Up to the side C1, preceding the one cutting edge 5x,
Since the other cutting edge that has passed between C2 has already been cut to the same width as the cutting width by the cutting edge 5x, the cutting edge 5x actually cuts the side surfaces C1 and C2 after all because of the arcs R ₀ and R _1.
(The shaded area in the figure).
That is, as described on the passing trajectory Q of the cutting edge 5x, the cutting by the cutting edge 5x is performed only between Ya and Yb1, Yb
Between 2, the end of the cutting blade 5x rubs against the side surfaces C1 and C2. Such rubbing unnecessarily promotes the wear of the cutting blade 5. Note that the passing track Q is actually a one to draw a convex curve bulge rotation center P ₀ side, is drawn close to the convenience straight line here.

In addition, in cutting with the turning broach 1, the cutting speed is set to about 200 m / min.
The cutting speed is determined by the side surface C1 where the actual cutting described above is performed,
The inner peripheral portion of C2 is used as a reference. Therefore, the cutting edge 5 and the side surface C
At the outer periphery of the counterweight C where the first and C2 rub against each other, the cutting speed becomes considerably high, and the wear of the cutting edge 5 is further spurred. Incidentally, 30 mm radius of curvature of the circular arc R ₁ in FIG. 10, when the curvature radius of the outer periphery of the counterweight C assuming 75 mm, by setting the cutting speed of the on arc R ₁ to 200 meters / min., The outer peripheral edge The cutting speed reaches 500 m / min., And the cutting edge 5 is approximately 2.
It will be rubbed five times faster. Then, as the cutting speed increases, the abrasion progress speed of the cutting edge increases at an accelerated rate.

As described above, in the conventional turning broach 1 described above, the life of the cutting blade 5 is shortened due to the friction between the cutting blade 5 and the increase in the cutting speed at the outer peripheral portion. Cutting edge 5 toward the rear end side
And the length at which the side surfaces C1 and C2 rub (Y in FIG. 10).
(b1 and Yb2 portions) become longer, and thus become more remarkable as the turning broach 1 moves toward the rear end side in the feeding direction. Therefore, the life of the cutting edge is significantly different between the front end side and the rear end side of the broach main body 2, and the replacement cycle of the cutting edge tip 3 is shifted, resulting in complicated tool management.

The above problem is not limited to the so-called spiral type turning broach 1 in which the cutting blades 5 are arranged in a fan shape while being shifted by an appropriate lift amount L as shown in FIGS. As shown in FIG. 11, a linear type turning broach 8 in which the cutting blade tip 3 is attached to one side of a rectangular flat broach body 7 by a predetermined lift amount L is similarly generated. Also, unlike these turning broaches 1 and 8, the cutting blade 5 is positioned in the same arc without giving a lift to the cutting blade tip 3, and the broach body is fed by an amount corresponding to the lift L during machining. The same applies to the so-called circular type turning broach 9 described above.

[0010] The present invention has been made under the above-mentioned background, and prevents wear due to friction between a cutting blade and a work, thereby improving the life of the cutting blade, and thereby achieving a uniform life of the cutting blade. It is intended to provide a turning brooch that can be obtained.

[0011]

In order to solve the above-mentioned problems, in the turning broach of the present invention, the protruding amount of a plurality of cutting blades for side cutting to the outside in the width direction of the broach body is determined by feeding the broach body. The direction is changed so as to be smaller on the rear end side than on the front end side.

Here, the manner in which the amount of protrusion of the cutting blade in the width direction of the broach body changes may be changed as appropriate in accordance with the state of wear of each cutting blade. Is divided into a plurality of cutting blade groups along the feed direction of the broach main body, and the protruding amount of each cutting blade in the broach main body width direction is stepped for each of these cutting blade groups. Can be effectively reduced. In this case, the difference in the protrusion amount in the broach body width direction for each cutting blade group is such that the difference in the protrusion amount in the broach body width direction between two cutting blade groups adjacent in the feed direction of the broach body is 0.01 mm. It is preferable that the distance is set to be within a range of 0.1 mm.

In order to further homogenize the life of the cutting blade, the amount of protrusion of the cutting blade in the width direction of the broach body is gradually reduced from the leading end to the rear end in the feeding direction of the broach body. Is preferred. In this case, the degree of change in the amount of protrusion is such that the difference in the amount of protrusion between two cutting blades that protrude to the same side in the width direction of the broach body and are adjacent to each other in the feed direction of the broach body is 0.005 to 0. It is preferable to set the distance to be within a range of 0.05 mm.

[0014]

According to the above construction, the end of the cutting blade on the side where the amount of protrusion in the broach body width direction is set to be small is smaller than the processing surface of the cutting blade where the amount of protrusion is set to be large in the direction of the broach body width. Since it retreats to the center side, the processing surface formed by the preceding cutting edge and the cutting edge do not rub, and thereby, among the cutting edges for side surface cutting, the cutting surface is arranged particularly on the rear end side in the feed direction of the broach body. Rubbing of the cutting blade is suppressed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The turning broach according to the present embodiment has a feature in the arrangement of the cutting blades for side processing. Before describing the arrangement, the overall configuration will be described with reference to FIGS.

As shown in FIGS. 2 to 5, the turning broach 10 according to the present embodiment includes a liner 1 which is curved in an arc shape.
A plurality of segments 12 to 14 are attached to an outer peripheral portion of the broach body 15 along a circumferential direction to form a fan-shaped broach body 15.
A plurality of cutting edge tips 16 made of cemented carbide are arranged in a zigzag pattern on the outer peripheral portion of the first segment 12 located on the front end side in the circumferential direction among the outer peripheral portions of the broach body 15. Attached to the first segment 1
A plurality of journal processing cutting blade tips 17 are attached to a portion of the outer peripheral portion behind the cutting blade tip 16 and an outer peripheral portion of the second segment 13 and subsequent portions located behind the first segment 12. It is schematically configured. Although only three segments are shown in the figure, an arbitrary number of similar segments are actually provided behind the third segment 14.

As shown in FIG. 5, the liner 11 is detachably mounted on the rotating shaft S by a plurality of bolts 18 inserted from the outer peripheral portion thereof, and a key groove 19 formed on the inner peripheral portion has a rotating shaft S. The rotation axis S is engaged with the key 20 on the
And can be integrally rotated. Also, FIG.
As shown in FIG. 4, the first segment 12 is provided at the center in the width direction and protrudes to the outer peripheral side of the segment 12, and is provided on the base end side of the convex wall 21. The positioning projection 2 includes a flange 22 extending in the width direction of the segment 12 and a positioning projection 23 projecting to the inner peripheral side of the segment 12.
3 is positioned in the width direction of the broach body 15 by being engaged with a groove (not shown) on the outer peripheral portion of the liner 11, and further, a bolt 25 inserted into the bolt mounting hole 24.
Are screwed into the liner 11 and are detachably attached to the liner 11.

A key 26 is arranged between the outer peripheral portion of the liner 11 and the inner peripheral portion of the segment 12, and care is taken to securely restrain the movement of the segment 12 in the circumferential direction. Further, the bolt mounting hole 24 has a configuration in which a bolt seat 24a that engages with the head of the bolt 25 is provided only at one end of the elongated hole so that the segment 12 can be attached and detached without removing the bolt 25.

The outer peripheral surface of the convex wall portion 21 of the segment 12 is formed in a spiral shape in which the distance from the inner peripheral surface of the broach body 15 gradually increases from the front end to the rear end in the circumferential direction. The same applies to the second segment 13 and the subsequent segments located rearward in the circumferential direction from the first segment 12. A chip mounting groove 27 is provided at both ends in the width direction of the outer peripheral portion of the convex wall portion 21 of the first segment 12 at the same distance in the circumferential direction, and one end and the other end of the broach body 15 in the width direction. Are formed so as to be shifted from each other in the circumferential direction.

In the chip mounting grooves 27, the cutting blade tip 16 is connected to one end of each cutting blade 28 by the segment 1.
2 is detachably attached by bolts 29 in a state of protruding outward from the second convex wall portion 21 in the width direction of the broach body 15, so that the distal end side outer peripheral portion of the broach body 15 is similar to the above-described conventional example. _A row of cutting blades EA protruding to one side in the width direction of the broach body 15 and the broach body 1
5 and another cutting edge row E _B protruding toward the other widthwise side of the is formed (see FIG. 4). In addition, each cutting blade tip 16
The cutting blades 28 are attached so that the respective cutting blades 28 gradually protrude toward the outer peripheral side of the broach main body 15 from the front end side to the rear end side of the broach main body 15.

[0021] Each cutting edge row E _A as shown in more detail in FIG. 1, (shown only in FIG. 1 cutting edge row E _A.) E _B is three switching circumferentially adjacent brooch body 15 Blade tip 1
As a group of 6 of the cutting edge 28 a to 28 c, each column E _A, E _B is divided into three cutting groups _{E A 1~E A 3, E B} 1~E B 3,
The amount of projection of the broach body width direction of the cutting edge 28a~28c for each of these cutting groups _{E A 1~E A 3, E B} 1~E B 3, i.e. from the widthwise center line m of the convex wall portion 21 each Cutting blade 28a-2
The distance x to the end of 8c is set stepwise smaller. Projecting amount of the cutting edge group E _A 2, E _B 2 to abutment against the cutting edge group E _A 1, E _B 1 of protruding amount x to be arranged in the circumferential direction tip of specifically broach body 15 only δ1 Set smaller,
Projecting amount of the cutting edge group E _A 3, E _B 3 is set further δ2 as small.

[0022] Here, the cutting group _{E A 1~E A 3, E B} 1
Difference δ1 of the projection amount between ~E _B 3, δ2 but is intended to be appropriately changed depending on the number of cutting insert 16 for the radius of curvature or side cutting of the counterweight C of the workpiece W,
It is preferable that the distance be set in the range of 0.01 to 0.1 mm. If it is less than 0.01 mm, the effect of preventing the abrasion and abrasion of the cutting blade 28 described later may not be sufficiently obtained. On the other hand, if it exceeds 0.1 mm, the width between the side surfaces C1 and C2 of the counterweight C becomes smaller. This is because there is a large difference between the outer circumferential side and the inner circumferential side of C, and there is a possibility that the tolerance exceeds the tolerance allowed in manufacturing.

In FIGS. 2 and 3, reference numeral 30 denotes a tip pocket of the cutting edge tip 16, and 31 denotes a cutting edge tip 17.
It is a chip pocket.

In the turning broach 10 configured as described above, the broach body 15 is driven to rotate at a low speed along the circumferential direction with respect to the workpiece W that is rotated at a high speed. 16 cutting blades 28
Are sequentially inserted between the side surfaces C1 and C2 of the counterweight C from the circumferential front end side of the first segment 12, and the side surface C
1, C2 is gradually cut into a predetermined shape toward the center in the radial direction.

Here, the turning broach 1 of this embodiment is described.
In 0, it is set as the protrusion amount x to the broach body width direction of the cutting edge 28 for side cutting is reduced stepwise for each cutting group _{E A 1~E A 3, E B} 1~E B 3 since it is, first side C1, the cutting group is cut into C2 E _a 1, E _B cutting group E _a 2 than machined surface formed by a cutting edge 28,
End of the E _B 2 of the cutting edge 28 is retracted to broach widthwise center side, similarly end cutting group E _A 1 of the cutting edge group E _A 3, E _B 3 of the cutting edge 28, E _A 2 , E _B 1, and E _B 2 are retracted toward the center side in the broach width direction from the processing surface formed by the cutting blade 28.
Thus, cutting blade group _{E A 2, E A 3,} E B 2, E B 3 of the cutting edge 28
Does not rub against the machined surface formed by the cutting blade group that has passed through the work W before, and only actually cuts the side surfaces C1 and C2 into an arc shape by a width corresponding to the lift amount L.

For this reason, rubbing wear of the cutting blade 28 is suppressed,
As a result, the life of the cutting blade 28 is more improved in the group of cutting blades located on the rear end side of the first segment 12 than in the related art, and the uniformity of the life of the cutting blade is achieved. In the same cutting blade group, the cutting blades 28b and 28c first rub against the processing surface of the cutting blade 28a passing between the side surfaces C1 and C2. It does not significantly affect the homogenization of wear.

The above cutting unit, especially the amount of projection of the broach body width direction of the cutting edge 28 in the embodiment _{E A 2, E B 2,} E A 3,
Although it is decreased step by step every E _B 3, the present invention is not limited to such an embodiment. For example, as shown in FIG. 6, one cutting edge row E _A, all of the cutting edge 28 in the E _B
May be gradually reduced toward the center in the width direction of the broach body 15 from the front end side to the rear end side in the circumferential direction of the broach body 15 to gradually reduce the amount of protrusion. In this case, since the rubbing wear of each cutting edge 28 is completely eliminated, homogenization of the life of the cutting edge can be more completely achieved. At this time, the difference λ between the protrusion amounts of the two adjacent cutting blades 28 in the broach body width direction is 0.005 mm for the same reason as the difference δ1, δ2 of the protrusion amounts in the above-described embodiment.
It is preferable to set the range to 0.05 mm.

In the example shown in FIGS. 1 and 6, the cutting blade 2
Although the amount of projection of the width direction of the 8 brooch body 15 is varied at least two or more stages, the present invention is not limited thereto, the same cutting edge row E _A, the protrusion amount in the E _B one Naturally, the case where only the stage is changed is included. After all, cutting blade 2
The degree of change in the protruding amount in the width direction of the broach body 8 may be appropriately changed according to the degree of unevenness of the cutting blade wear of the turning broach to which the present invention is applied. It is not limited to the embodiment shown.

Further, in the above embodiment, an example in which the present invention is applied particularly to a spiral type turning broach has been described. However, the present invention is not limited to this, and a linear type shown in FIG. 11 and a circular type shown in FIG. Even if there is, it can be applied. Further, not only a throw-away type in which the cutting blade tip 16 is detachably mounted, but also a solid type in which the cutting blade tip is brazed or a cutting blade and a broach body are integrally formed. Applicable.

[0030]

As described above, according to the turning broach of the present invention, of the cutting blades for cutting the side surface, the cutting blade is formed by the cutting blade whose projection amount in the width direction of the broach body is set relatively large. Since the end of the cutting blade whose protrusion amount is set relatively small with respect to the processing surface to be retracted retreats toward the center in the width direction of the broach body, the end of the cutting blade and the workpiece are prevented from rubbing each other. Abrasion is suppressed. Therefore,
The life of each cutting edge is improved by improving the life of the cutting edge arranged in the feed direction of the broach body in particular, so that the life of each cutting edge is homogenized, and thus the life of each cutting edge in one cutting edge row. And tool management can be facilitated.

[Brief description of the drawings]

FIG. 1 is a view showing an arrangement of cutting blades according to an embodiment of the present invention projected onto one section of a work.

FIG. 2 is a plan view of a segment constituting a broach main body according to an embodiment of the present invention.

FIG. 3 is a view as seen from the direction of arrow III in FIG. 2;

FIG. 4 is a view from arrow IV in FIG. 3;

FIG. 5 is a side view showing an entire configuration of a turning broach according to an embodiment of the present invention.

FIG. 6 is a diagram showing a modification of FIG. 1;

FIG. 7 is a perspective view for explaining a general crankshaft cutting method using a turning broach.

FIG. 8 is a diagram for explaining a cutting method using a spiral type turning broach.

FIG. 9 is a diagram showing an arrangement of cutting blades in a conventional turning broach projected on one cross section of a work.

FIG. 10 is a diagram showing a passage trajectory of a cutting blade and an actual cutting area when the counterweight is cut by the turning broach in a side view of the counterweight.

FIG. 11 is a diagram for explaining a cutting method using a linear type turning broach.

FIG. 12 is a view for explaining a cutting method using a circular type turning broach.

[Explanation of symbols]

10 Turning broach 15 broach body 16 cutting edge E _A one cutting edge row E _B another one cutting edge row of cutting inserts 28 for side cutting for side cutting E _A 1, E _A 2, E _A 3 one cutting group E _B 1 of the cutting blade row, E _B 2, E _B 3 projecting amount of the cutting blade group x cutting edge of the other one of the cutting edge row .delta.1, .delta.2, the difference between the amount of projection of λ cutting edge

Claims (5)

(57) [Claims] 1. A plurality of cutting blades for side cutting are provided at one side of a broach main body at intervals in a feed direction of the broach main body, and at least one end of each of the cutting blades is directed outward in a width direction of the broach main body. In the turning broach that is mounted so as to protrude, the amount of the plurality of side surface cutting cutting edges protruding outward in the width direction of the broach body becomes smaller at the rear end side than the front end side in the feed direction of the broach body. Turning brooch characterized by being changed as follows. 2. The cutting blades for cutting a plurality of side surfaces are divided into a plurality of cutting blade groups along a feeding direction of the broach body,
The projecting amount of each cutting blade outwardly in the broach width direction for each of the cutting blade groups decreases stepwise as going from the front end side to the rear end side in the feed direction of the broach body. The turning broach of claim 1. 3. The turning broach according to claim 2, wherein, of the plurality of cutting blade groups, the difference in the amount of protrusion between the cutting blades of two cutting blade groups adjacent to each other in the feed direction of the broach body is 0. A turning broach characterized by being set in a range of from 01 mm to 0.1 mm. 4. The projecting amount of the plurality of side surface cutting blades outward in the width direction of the broach body gradually decreases from the leading end to the rear end in the feeding direction of the broach body. A turning broach according to claim 1, characterized in that: 5. The turning broach according to claim 4, wherein two of the plurality of cutting blades protrude to the same side in the width direction of the broach body and are adjacent to each other in the feed direction of the broach body. A turning broach characterized in that the difference in the amount of protrusion in the width direction of the main body is set in a range of 0.005 to 0.05 mm.