JP5573684B2 - Helical brooch - Google Patents

Description

  The present invention relates to a helical broach used for cutting a workpiece having a twisted groove on its inner periphery, such as a helical internal gear.

As helical internal gears, for example, planetary internal gears are provided in various ways as gears for automatic transmissions. Recently, as the required quality of automatic transmissions increases, so does the quality of gears. It is becoming.
As a helical broach used for processing such a helical internal gear, for example, in Patent Document 1 below, a plurality of cutting blades projecting radially outward of the broach main body are provided on the outer peripheral portion of the shaft-shaped broach main body. The blades are arranged in a spiral shape that twists around the axis of the broach body from the front end side to the rear end side of the broach body, and the cutting edge at the front end side of the broach body is a rough edge (outer diameter increasing blade). At the same time, the cutting blade on the rear end side of the broach body is a finishing blade (tooth thickness increasing blade). In this finishing blade, either the rake face facing the front end side of the broach body or the circumferential direction of the broach body A cutting blade is formed at an intersecting ridge line portion with a side surface facing the surface, and an intersecting ridge line portion between the side surface opposite to the cutting blade and the rake face is a guide blade.

  According to such a helical broach, for example, as shown in FIG. 6, the tooth profile of the helical internal gear as the workpiece W is formed from the small diameter portion to the required groove depth Ha by the rough blade whose tooth height gradually increases. After that, with a finishing blade whose tooth thickness gradually increases, first, one side of the tooth profile (for example, the side Sb on the acute angle side) is driven into the tooth thickness direction, and then the other side surface of the tooth profile (for example, the obtuse angle side) The side surface Sa) is driven and cut in the tooth thickness direction, whereby the left and right side surfaces can be brought closer to a desired involute curve.

JP 2007-253298 A

Such a helical broach is intended to approximate the left and right sides of the workpiece to the desired involute curves Ia and Ib, respectively, even at the time of cutting with a rough blade. As shown in FIG. 7, when cutting the tooth profile of the workpiece in the tooth height direction, the rough blade gradually shifts to an acute angle side as shown in FIG. 7 (the amount of deviation at the uppermost portion in FIG. Show). For this reason, immediately after cutting with a rough blade, the side surface Sa on the obtuse angle side of the workpiece tooth profile is greatly deviated from the involute curve Ia on the obtuse angle side.
Therefore, when cutting the workpiece tooth profile in the tooth thickness direction with the finishing blade and cutting the side surface closer to the desired involute curved surface Ia, the thickness to be cut by the finishing blade differs between the tooth base and the tooth tip. Therefore, uneven wear occurs in the finishing blade. As a result, the helical broach has a problem that it has to be reground frequently or the life of the helical broach is shortened.

  The present invention was made under such a background, and when the tooth profile of the workpiece is cut in the tooth length direction by the outer diameter rising blade, the side surface of the workpiece tooth profile can be brought close to the involute curve, An object of the present invention is to provide a helical broach capable of avoiding uneven wear on the finishing blade and extending the life.

In order to solve the above problems and achieve such an object, the helical broach of the present invention is:
A plurality of cutting blades projecting radially outward on the outer peripheral portion of the shaft-shaped broach main body in a row and spirally twisted around the axis of the broach main body from the front end side to the rear end side And a plurality of the cutting blades in a helical broach in which a row of the cutting blades are arranged at intervals in the circumferential direction to form a twisted groove of a predetermined lead on the inner periphery of the machining hole of the workpiece by these cutting blades Among them, the plurality of cutting blades on the front end side of the broach body are the outer diameter rising blades whose tooth length is gradually increased in order to cut the tooth profile of the work in the tooth height direction, and the plurality of cutting blades on the rear end side of the broach body are workpieces The tooth profile is gradually increased in order to drive the tooth profile in the tooth thickness direction and cut into an involute curved surface, and when the plurality of outer diameter increasing blades in a row are stacked in the tooth height direction, Outer diameter rising edge side edge of obtuse angle side is up To involute curved surface, characterized in that it is formed in a shape deviated gradually to increase the amount of deviation outwardly toward the tooth depth direction.

  According to the helical broach having the above configuration, when cutting the tooth profile of the workpiece in the tooth height direction by the outer diameter rising blade, considering that the outer diameter rising blade gradually shifts to the acute angle side, the obtuse angle side of the outer diameter rising blade Since the side blade is formed in a pre-shifted shape so as to gradually increase the amount of deviation outward (obtuse angle) as it goes in the tooth height direction with respect to the involute curved surface, the tooth profile of the workpiece is formed by the outer diameter rising blade. It is possible to form the obtuse angle side surface of the workpiece tooth profile immediately after cutting in the tooth height direction into a shape approximating an involute curve.

When the plurality of outer diameter rising blades forming a row are stacked in the tooth height direction, it is preferable that the side blades on the acute angle side of the outer diameter rising blades are formed in the same shape as the involute curved surface.
According to this type of helical broach, as described above, when the tooth profile of the workpiece is cut in the tooth height direction by the outer diameter rising blade, the outer diameter rising blade tends to gradually shift to the acute angle side. When the workpiece tooth profile is cut by the new outer diameter rising blade at the rear side on the acute angle side surface of the outer diameter rising blade at the position shifted to the side, cutting is performed from the workpiece tooth tip at the shifted position to the workpiece tooth base direction. . In this case, since the side blade on the acute angle side of the outer diameter rising blade is formed in an involute curved surface, the tooth profile after cutting is directly transferred to the workpiece tooth profile. In other words, the acute side of the workpiece tooth profile immediately after cutting the tooth profile of the workpiece in the tooth height direction by the outer diameter rising blade is formed into a shape that approximates the involute curved surface that is the shape of the side blade on the acute angle side of the outer diameter rising blade. It becomes possible to do.

The deviation amount X (mm) of the side blade on the obtuse angle side of the outer diameter rising blade with respect to the involute curved surface is as follows when the lead value is R (mm) and the tooth height of the outer diameter rising blade is H (mm): It is preferable to be set within the range represented by the formula:
X = R × 0.0000479 + H × 0.00624 ± 0.01
As a result of various experiments, the inventors set the deviation amount X (mm) of the side blade on the obtuse angle side of the outer diameter rising blade with respect to the involute curved surface within the above range, thereby performing the follow-up cutting with the outer diameter rising blade. It was confirmed that the obtuse angle side surface of the work tooth profile immediately after forming can be formed into a shape very close to the involute curve.

  According to the helical broach of the present invention, the workpiece tooth profile immediately after cutting the workpiece tooth profile in the tooth length direction by the outer diameter rising blade can be made into a shape approximating the involute curve, and the tooth thickness increasing blade used for the subsequent processing The occurrence of uneven wear can be avoided. As a result, the frequency of re-grinding can be reduced, and the life of the helical broach can be extended without difficulty.

It is a side view which shows embodiment at the time of applying this invention to an off-normal type helical broach. It is sectional drawing which shows a part of workpiece | work processed with the helical broach of embodiment shown in FIG. It is a schematic diagram explaining the outer diameter rising blade of the helical broach of embodiment shown in FIG. FIG. 2 is a schematic diagram illustrating an outer diameter rising blade of the helical broach of the embodiment shown in FIG. 1, wherein the outer diameter rising blade is laminated in a tooth height direction. It is explanatory drawing which shows the example which cuts a workpiece | work with an outer diameter rising blade. The state which cut | disconnected the workpiece | work with the outer diameter rising blade and the tooth thickness rising blade is shown. The state which cut | disconnected the workpiece | work with the rough blade (outer diameter rising blade) of the conventional helical broach is shown.

  1 to 4 show an embodiment of an integrated helical broach according to the present invention, and FIG. 1 is a side view showing the embodiment when the present invention is applied to an off-normal helical broach. These are sectional drawings which show a part of workpiece | work processed by the helical broach of embodiment shown in FIG.

The helical broach of this embodiment is for broaching a workpiece having a twisted groove D on its inner periphery, such as the helical internal gear G shown in FIG. 2 such as the planetary internal gear described above. As shown in FIG. 1, the broach main body 1 has a long shaft shape centered on the axis O, and both end portions thereof are grip portions 2 and 3, and a cutting blade is provided between the grip portions 2 and 3. Part 4. A plurality of cutting blades 5 projecting radially outward with respect to the axis O are provided on the outer periphery of the broach main body 1 in the cutting blade portion 4 from the front end side (left side in FIG. 1) of the broach main body 1 to the rear end. They are arranged so as to form a spiral along the lead L twisted around the axis O toward the side (right side in FIG. 1). A plurality of rows of these cutting blades 5 are formed at intervals in the circumferential direction.
FIG. 1 shows an embodiment of the present invention for an off-normal type (helical blade groove type) integrated helical broach in which a blade groove formed between a plurality of cutting blades 5 in the direction of the axis O is twisted around the axis O. An applied example is shown.

Here, a plurality of cutting blades 5 at the tip side of the broach body 1 in the cutting blade portion 4 are outer diameter rising blades 6 that cut the tooth profile of the helical internal gear in the tooth length direction. In the rising blade 6, the tooth height of the cutting blade 5 is sequentially increased toward the rear end side of the broach body 1 along the row of the cutting blades 5. Further, the cutting edge portion 4 on the rear end side of the broach body 1 with respect to the outer diameter rising blade 6 has both the tooth surface of the tooth profile cut by the outer diameter rising blade 6 to a predetermined tooth height, that is, the twist groove of the workpiece. A plurality of tooth thickness increasing blades 7 are formed to drive the groove side surface in the tooth thickness direction, that is, the circumferential direction of the broach main body 1 to form a predetermined tooth thickness.
In addition, round blades for cutting the small-diameter portion of the tooth profile are provided alternately with the tooth thickness increasing blade 7 in the portion of the cutting edge portion 4 where the cutting blade 5 that is the outer diameter increasing blade 6 is arranged. Also good. The round blade may be provided on the rear end side of the tooth thickness increasing blade 7. The outer diameter rising blade 6, the tooth thickness increasing blade 7, and all the cutting blades 5 of the round blade are integrally formed in the broach body 1 in this embodiment.

  FIG. 3 is a schematic view for explaining an outer diameter rising blade of the helical broach according to the embodiment shown in FIG. FIG. 4 illustrates the outer diameter rising blade of the helical broach of the embodiment shown in FIG. 1, and is a schematic diagram in which the outer diameter rising blade is laminated in the tooth height direction.

  A plurality of outer diameter rising blades 6a, 6b,..., 6g in a row (in FIG. 4 and FIG. 5, the number of outer diameter rising blades is seven for the sake of convenience, but in reality, a larger number is provided). Although the outer diameter rising blades 6a, 6b, to 6g are forcibly laminated in the tooth height direction (upward in FIG. 4) without shifting, the outer diameter increases. The side blades 6aa, 6ba, to 6ga on the obtuse angle side of the rising blade have an amount of deviation outward (obtuse angle side) toward the tooth height direction with respect to the involute curved surface Ia on the obtuse angle side (left side in FIG. 4) of the work tooth profile. The shape is shifted so as to gradually increase.

  Here, the acute angle side and the obtuse angle side of the outer diameter rising blade are referred to based on the angle formed by the rake face and the side clearance surface in the outer diameter rising blade. Here, as shown in FIG. When viewed from the front with the lead L as the center, the left side is the obtuse angle side and the right side is the acute angle side.

Further, the deviation amount X (mm) with respect to the involute curved surface of the side blades 6aa, 6ba, to 6ga on the obtuse angle side of the outer diameter rising blade is R (mm) for the value of the lead L, and the tooth height of the outer diameter rising blade is H ( mm), it is set to be in the range represented by the following formula.
X = R × 0.0000479 + H × 0.00624 ± 0.01
This equation is a result obtained from the multiple regression analysis by the inventors of the present invention. The final term 0.01 (mm) in this equation is a value that takes into account manufacturing errors and processing errors.

  Here, when the outer diameter rising blades 6a, 6b, to 6g are forcibly stacked in the tooth height direction (upward in FIG. 4) without being displaced, the side blades 6ab on the acute angle side of the outer diameter rising blades 6ab, 6bb and ˜6gb are formed to have the same shape as the involute curved surface Ib on the acute angle side (right side in FIG. 4) of the work tooth profile.

  As shown in FIG. 1, the plurality of tooth thickness increasing blades 7 are provided on the tip side of the broach main body 1 following the outer diameter increasing blade 6 among the tooth thickness increasing blades 7, A plurality of tooth-thickening blades 7A for driving and cutting one wall surface of the groove wall surfaces, and the other end of the groove wall surfaces provided on the rear end side of the broach body 1 of these tooth-thickness blades 7A. A plurality of tooth thickness increasing blades 7B for driving and cutting the wall surface are provided.

  In other words, in each tooth thickness increasing blade 7, there is a rake face that faces the tip side of the broach main body 1 of the cutting edge 5 and a side face that faces the side of the groove wall in the circumferential direction of the broach main body 1 where the groove wall is driven and cut. Cutting blades are formed at the intersecting ridge lines. On the other hand, on the cross ridge line portion of the rake face on the opposite side in the circumferential direction to the cross ridge line portion thus formed with the cutting blade, the groove wall surface of the torsion groove opposite to the groove wall surface driven and cut by the cutting blade is provided. A guide blade that slides and guides the tooth thickness increasing blade 7 is formed.

  In the plurality of tooth thickness increasing blades 7A on the front end side of the broach main body 1, the obtuse angle side guide blades are arranged along the lead L and the acute angle side cutting blade is arranged along the lead L at the rear end. In the plurality of tooth thickness increasing blades 7B on the rear end side of the broach main body 1, the guide blades on the acute angle side thereof are generally arranged on the broach main body 1 while being gradually protruded in the tooth thickness direction toward the side. Among the plurality of tip-thickening blades 7A on the front end side, the cutting blade on the rear end is arranged so as to continue along the lead L, and the cutting blade on the obtuse angle side is a tooth-thickness increasing blade on the front end side of the broach body 1 It is arranged so as to gradually protrude in the tooth thickness direction from the guide blade of 7A toward the rear end side along the lead L.

  Note that the torsional groove formed by the outer diameter rising blade 6 is substantially equal to the distal end side of the tooth thickness increasing blade 7A on the front end side of the broach body 1, that is, between the outer diameter increasing blade 6 and the tooth thickness increasing blade 7. A guide blade (not shown) having a width and tapered on both ends is provided with a negative clearance angle.

Next, a method for cutting a workpiece with the thus configured helical broach will be described.
The broach main body 1 is inserted from the front end side into a processing hole formed in advance in the work W, and the broach main body 1 is rotated along the lead L while being advanced relative to the work. Thereby, first, a torsion groove having a predetermined depth is formed on the inner surface of the hole of the workpiece W by the outer diameter rising blade 6.

  Here, in the helical broach having the above configuration, when the tooth profile of the workpiece is cut in the tooth height direction by the outer diameter rising blade 6, the outer diameter rising blade 6 is gradually shifted to an acute angle side, The obtuse side blade is formed in a pre-shifted shape so as to gradually increase the amount of outward bias toward the tooth height direction with respect to the involute curved surface.

  FIG. 5 is an explanatory view showing an example in which a workpiece is cut by an outer diameter rising blade 6 formed in a shape deviated in advance with respect to the involute curve. As shown in FIG. 5, when the tooth profile of the workpiece is cut in the tooth height direction by the outer diameter rising blade 6, the outer diameter rising blade 6 on the rear stage side gradually shifts to an acute angle side. The side surface S on the obtuse angle side of the workpiece tooth profile immediately after the follow-up cutting by means of a shape approximates the involute curve Ia on the obtuse angle side.

Further, when the deviation X (mm) of the side blade on the obtuse angle side of the outer diameter rising blade with respect to the involute curved surface is R (mm) and the tooth height of the outer diameter rising blade is H (mm) , It is set to be in the range represented by the following formula.
X = R × 0.0000479 + H × 0.00624 ± 0.01
As a result, it becomes possible to form the obtuse angle side surface S of the workpiece tooth profile immediately after the follow-up cutting with the outer diameter rising blade 6 into a shape very close to the involute curve Ia on the obtuse angle side.

Further, when the plurality of outer diameter rising blades 6 in a row are stacked in the tooth height direction, the acute angle side blades 6ab, 6bb,... 6gb of the outer diameter rising blade are the same as the acute angle involute curved surface Ib. It is formed into a shape.
According to this type of helical broach, when the tooth profile of the workpiece W is cut in the tooth height direction by the outer diameter rising blade 6 as described above, the outer diameter rising blade 6 tends to gradually shift to an acute angle side. As shown in FIG. 5, when the workpiece tooth profile is cut with the new outer diameter rising blade 6 on the rear side on the acute angle side surface of the outer diameter rising blade 6 as shown in FIG. Cutting from the tooth tip to the workpiece tooth root direction. In this case, since the side blades 6ab, 6bb,... 6gb on the acute angle side of the outer diameter rising blade are formed to have the same shape as the involute curved surface, the tooth profile after cutting is directly transferred to the workpiece tooth profile. That is, the acute angle side surface of the workpiece tooth profile immediately after cutting the workpiece tooth profile in the tooth length direction by the outer diameter rising blade 6 is approximated to an involute curved surface which is the shape of the side blade on the acute angle side of the outer diameter rising blade. It becomes possible to form.

Next, the tooth thickness on the tip side of the broach body 1 is guided while the guide blade of the tooth thickness increasing blade 7A on the tip side of the broach body 1 is in sliding contact with the wall surface on the obtuse angle side of the torsion groove. The sharp-side groove wall surface of the twisted groove is cut by the cutting blade of the rising blade 7A, and a finishing allowance is applied to the acute-side groove wall surface from the groove width by the outer-diameter rising blade 6.
Subsequently, the guide blade of the tooth thickness increasing blade 7B on the rear end side of the broach body 1 is brought into sliding contact with the groove wall on the acute angle side to guide the tooth thickness increasing blade 7B. The obtuse angled groove wall surface of the twisted groove is cut by the cutting blade of the end-side tooth thickness increasing blade 7B, and a finishing allowance is given from the groove width to the acute angle side groove wall surface to form a twisted groove having a desired groove width.

  Here, as described above, the obtuse angle side surface S of the workpiece tooth shape immediately after the follow-up cutting with the outer diameter rising edge 6 has a shape approximating the involute curve Ia on the obtuse angle side. When cutting the tooth profile of W in the tooth thickness direction and cutting the side surface closer to the involute curved surface (see FIG. 6), the thickness to be cut at the base and tip of the finishing blade 7 is substantially the same. Thus, it is possible to avoid uneven wear on the finishing blade 7. As a result, the frequency of re-grinding can be lowered and the long life of the helical broach can be easily achieved.

In addition, this invention is not limited to the above-mentioned embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, in the above-described embodiment, an example in which the present invention is applied to an off-normal type integrated helical broach has been described. However, the present invention is not limited thereto, and the present invention is also applicable to a straight shaft type helical broach or a tooth thickness. The present invention can also be applied to an assembled helical broach in which the rising blade 7 is provided in a shell separate from the broach body.

  Moreover, in the said embodiment, when the some outer diameter raising blade 6 which makes a row | line | column is laminated | stacked on the tooth-length direction, the shape which connected the side blades 6aa, 6ba, ... 6ga side of the obtuse angle side of the outer diameter raising blade 6 is connected. The involute curved surface Ia is formed in a shape that shifts outward as it goes in the tooth height direction, but is not limited thereto, and each of the side blades 6aa, 6ba,. You may form in a shape which shifts a part outward.

1 Brooch body 4 Cutting edge 5 Cutting edge
6 (6a, 6b... 6 g) Outer diameter rising blade 6aa, 6ba,... 6ga Outer diameter rising blade obtuse side blade 6ab, 6bb, ... 6gb Outer diameter rising blade acute angle side blade 7 Tooth thickness increasing blade H Tooth height X Deviation amount O Broach main body 1 axis L Lead of cutting edge 5 Ia Involute curve on obtuse angle side Ib Involute curve on acute angle side

Claims (3)

A plurality of cutting blades projecting radially outward on the outer peripheral portion of the shaft-shaped broach main body in a row and spirally twisted around the axis of the broach main body from the front end side to the rear end side In addition, in the helical broach in which the rows of the cutting blades are arranged at intervals in the circumferential direction, and a twisted groove of a predetermined lead is formed on the inner periphery of the work hole of the workpiece by these cutting blades,
Among the plurality of cutting blades, the plurality of cutting blades on the front end side of the broach body are outer diameter rising blades whose tooth length is gradually increased to cut the tooth profile of the workpiece in the tooth height direction, and a plurality of cutting blades on the rear end side of the broach main body. The cutting blade is a tooth thickness increasing blade that gradually increases the tooth thickness to drive the workpiece tooth shape in the tooth thickness direction and cut it into an involute curved surface,
When the plurality of outer diameter rising blades in a row are stacked in the tooth height direction, the obtuse angle side blades of the outer diameter rising blades are displaced outwardly toward the involute curved surface in the tooth height direction. A helical broach characterized by being formed in a shape shifted so as to gradually increase. The helical broach according to claim 1,
A helical broach characterized in that when the plurality of outer diameter rising blades forming a row are stacked in the tooth length direction, the acute side blades of the outer diameter rising blades are formed in the same shape as the involute curved surface. . The helical broach according to claim 1 or 2,
The amount of deviation X (mm) of the side blade on the obtuse angle side of the outer diameter rising blade with respect to the involute curved surface is defined as R (mm) as the lead value and H (mm) as the tooth height of the outer diameter rising blade. A helical broach characterized by being set in a range represented by the following formula.
X = R × 0.0000479 + H × 0.00624 ± 0.01

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