JPH10137890A - Manufacture of segment sprocket, and device for the manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To forge and finish an end face of a segment sprocket to the desired shape so that the end face need not be mechanically finished after forging by improving the technology to forge the segment sprocket. SOLUTION: A rough-finished segment sprocket semi finished product 12 is placed on a base die 4, a sprocket tooth surface is forged and finished by a tooth surface die A5 and a tooth surface die B6, and each end face of the segment sprocket semi finished product 12 is pressed to be forged and finished by a pair of end face die 7 (a forging die for finishing end face). When an upper die 15 is pressed toward the base die 4, an end face die driving inclined surface 15a of the upper die 15 is brought into slidable contact with an inclined surface 7a of the end face die 7, and the end face die 7 is pressed in the forging direction by the cam effect of the inclined surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for forging a segment sprocket constituting a sprocket of a tracked construction machine or a tracked agricultural vehicle, for example. .

[0002]

2. Description of the Related Art FIG. 7 is a front view showing an example of a sprocket in which 25 teeth are formed around a rib. Since the annular rib 1z has an inner flange shape, it may be called a flange portion. 25 teeth 1a around it,
The sprocket 1 is constituted by arranging 1b to 1y in a row. Since it is difficult to mold a large sprocket integrally, it is divided or cast or forged in the circumferential direction. Forged sprockets have fewer material defects and a finer grain size than cast sprockets,
Moreover, since the flow structure is such that impurities are in a fibrous state, the mechanical properties are excellent, and in particular, it is tough, has a high impact value and is of high quality. FIG. 8 is an explanatory diagram schematically showing an example of a five-tooth segment sprocket constituted by dividing the 25-tooth sprocket illustrated in FIG. 7 above into five equal parts in the circumferential direction, and schematically illustrating the sprocket. . In this example, sprocket 1 has 25
Since it is a single tooth, it is divisible by 5 and a 5-tooth segment
A sprocket 2 is configured. 2a to 2e are sprocket teeth. However, since the number of teeth of a sprocket is not always divisible by an integer, an N-tooth segment sprocket and an (N-1) -tooth segment sprocket (not shown) may be configured. The above N is generally an integer of 3 to 6.

[0003] The method of stamping and forging segment and sprockets is roughly classified into vertical and horizontal. FIG.
FIG. 2 is a view for explaining a vertical forging method of a segment sprocket, and is a diagram in which an arrow indicating a forging direction is added to a front view of a five-tooth segment sprocket. The vertical beating is a forging method in which a forging pressure in the radial direction is applied as indicated by arrows P ₁ and P _{2 in} the drawing, and the horizontal beating is a forging pressure in a direction perpendicular to the paper surface. In the above vertical and horizontal hits,
Although each has its pros and cons, vertical punching is suitable for precisely finishing the tooth profile. Conventionally, in general, after forging by horizontal striking, the tooth faces, ribs, end faces and the like are often finished by machining. 2 _H shown, the segment sprocket 2 A bolt holes for attachment to a hub (not shown), generally, are drilled by machining after forging.

FIG. 10 is a view for explaining a technical problem when the segment sprocket shown in FIG. 9 described above is vertically forged, and an auxiliary line is added to a front view of the segment sprocket. It is. Let XX be the center line of the rib 2z and consider a line {-} parallel to the center line XX with the teeth 2e located at the ends in contact. When a tangent tt of the tooth 2e is drawn at a point slightly closer to the root of the tooth 2e than a contact point between the tangent χ-χ and the tooth 2e, the tangent tt is more clearly drawn than the tangent χ-χ. And cross at a clockwise (φ) angle φ. The angle φ becomes a draft angle in the opposite direction in the vertical forging in the XX direction, and cannot be stamped and forged as it is. Therefore, after the die 2a _-1 shown in the tooth 2a is die-cut and forged with a die, it must be machined and cut off, which causes an increase in manufacturing cost. In order to solve the problem related to the reverse draft, the semi-finished product having no reverse draft, such as the segment, sprocket, and semi-finished product 3 shown by the chain line in FIG. A method of correcting the segment, sprocket, and target shape 2 is effective. The above method is based on the known invention filed by the present applicant (Japanese Patent Publication No. 3-41551).
Segment and sprocket forging method). Less than,
This technique is called a known invention.

FIG. 11 is a front view of a segment sprocket with an auxiliary line indicating a forging direction and an auxiliary line indicating a draft angle, showing an embodiment of a forging method of a segment sprocket according to the known invention. In the segment / sprocket / semi-finished product 3, the radius of curvature of the arcuate rib 3z is formed larger than the radius of curvature of the arcuate rib 2z of the target shape, and the sprocket teeth 3a and 3e at both ends are turned inward. All tangents (e.g., t'-t ') drawn at any point on the tooth are centered X
It is configured to have a forward draft (for example, an angle θ) with respect to the auxiliary axis χ-χ parallel to −X. When the segment / sprocket / semi-finished product 3 is forged in a direction to reduce the radius of curvature, the segment / sprocket / target shape 2 is obtained.

[0006]

According to the above-described known invention, a segment sprocket having a relatively large number of teeth can be stamped and forged by a vertical driving method with high tooth surface accuracy, and the draft angle can be reduced. There is no longer any need to add meat to make it. The present applicant has conducted industrial mass production of segment sprockets by the method according to the above-mentioned known invention, confirmed that the practical effect is remarkable, and discovered that there is a prediction of further improvement. . That is, the segment, sprocket, and target shape 2 forged by the known invention method shown in FIG. 11 can be used as a finished product without machining the tooth surface, and a high-quality product at low cost can be obtained. can get. However, the end face 2T (FIG. 11, known invention) corresponding to the division surface when the annular rib (see FIG. 7 and denoted by reference numeral 1z) is divided must be machined and finished precisely. Since the sprocket to which the present invention is applied is a driving member for driving the vehicle while touching earth and sand, it does not require micron-order accuracy such as a watch part or a camera part. When an annular sprocket is formed by combining the segment sprockets, the end face 2T is a positioning surface between adjacent segment sprockets and is a part that appears in the appearance of a product equipped with a sprocket. This end face 2T
Is generally less than one millimeter. Therefore, regardless of whether the known invention is applied or not, a finished product is obtained unless the divided surface of the stamped and forged segment sprocket (in the present invention, the divided surface and the end surface are the same) is finished by machining. I couldn't. The present invention has been made in view of the above-described circumstances, and performs finish forming by stamping forging so that good sprocket tooth surface accuracy can be obtained, and furthermore, does not require machining of the end face of the segment. An object of the present invention is to provide a method of manufacturing a sprocket and an apparatus for manufacturing the same. Although the present invention is an improvement of the above-mentioned known invention, it is also possible to carry out the invention in combination with the known invention, and it is also possible to carry out the present invention alone (without using the known invention). It seeks to improve as much as possible.

[0007]

The basic principle of the present invention created to achieve the above object will be briefly described with reference to FIG. 1 corresponding to an embodiment of the present invention. The semifinished product 12 of the sprocket is placed on the base die 4 for finish forging, and the tooth surface mold / instep 5 and the tooth surface type / part 6 for finishing and forging the sprocket teeth are pressed. The end face mold 7 is pressed against the end face to finish form (forge) the end face. As a result, the divided surface (same as the end surface) of the sprocket divided into segments is forged to the extent that finishing by machining is not required. Based on the principle described above, the method according to the first aspect of the present invention is directed to a segment sprocket having a plurality of teeth obtained by dividing a sprocket having teeth arranged around an annular rib in a circumferential direction. In the method of forging and molding a semi-finished product of a segment sprocket having a draft on the tooth surface of the sprocket, a forging die for a tooth surface is applied to the tooth surface of the semi-finished segment sprocket. Then, it is pressed hot and plastically deformed to eliminate the draft formed on the tooth surface of the sprocket. The forging die is pressed in the tangential direction to be plastically deformed, and the semi-finished product of the segment sprocket is finished and forged into a target shape. According to the first aspect of the present invention described above, the draft remaining on the tooth surface of the semifinished segment sprocket is corrected by using a tooth surface forging die to remove the draft, and the segment / sprocket is removed. Since the forging die is pressed against the end face of the sprocket semi-finished product to finish and forge into the desired shape, there is no need to machine the end face after forging. For this reason, compared to the forging method of the segment sprocket according to the known invention, machining of the end face after forging becomes unnecessary without increasing the forging process, and the manufacturing cost can be reduced without lowering the product quality. it can.

The structure of the method according to the second aspect of the present invention is the same as that of the first aspect.
In addition to the configuration of the method of the invention, the semi-finished product of the segment and sprocket having a reduced radius of curvature by enlarging the radius of the annular rib as compared with the segment and sprocket of the target shape is roughly finished by hot forging and trimmed. After performing the care, the forging die for the tooth surface is subjected to a correction finish for removing draft, and in the same process, the forging die for the tooth surface is used to reduce the radius of the annular rib, thereby increasing the curvature. It is characterized in that it is finish forged into a target shape by plastically deforming it in a form to increase the number. According to the second aspect of the present invention, when the sprocket is divided into segments to form a segment sprocket, the number of divisions is reduced, and the number of sprocket teeth formed on one segment sprocket is compared. Even if the target is increased, it is possible to prevent the occurrence of a reverse draft in the vertical forging of sprocket teeth. That is, without impeding the configuration of the known invention, and without impairing the effects of the known invention, and without increasing the number of forging steps of the known invention, the present invention is applied to the end face machining after forging. Is unnecessary, and a high quality segment sprocket can be manufactured at lower cost.

The structure of the method according to the third aspect of the present invention is the same as that of the second aspect.
In addition to the configuration of the invention method, a plurality of circumferentially divided tooth surface forging dies are applied to the semifinished product of the segment sprocket, and the divided tooth surface forging dies are applied in the respective radial directions. It is characterized by pressing. According to the third aspect of the present invention described above, the "plastic deformation in which the radius of the annular rib is reduced to increase the curvature" in the second aspect of the invention can be easily and reliably performed. In addition, the degree of draft of the sprocket tooth surface draft angle in the finish forging has a large degree of design freedom, and the mold separation at the end of the finish forging can be improved.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect of the invention, a draft removal finish by the tooth surface forging die and a division surface finish by the end surface forging die are provided. At the same time, the side surface of the sprocket teeth is finished by applying a forging pressure in the lateral hitting direction to the semi-finished product of the segment sprocket through a forging die. According to the invention of claim 4 described above, even if the side surfaces of the sprocket teeth do not have sufficient dimensional accuracy at the time of rough finishing or the surface roughness of the side surfaces is not good, the tooth surface and the end surface are not affected. At the same time as the modified forging, the modified forging of the side surface is performed, and all the outer peripheral surfaces of the segment sprocket are finished to the target shape (dimensions and surface roughness) in the same process.

According to a fifth aspect of the present invention, a sprocket having teeth arranged in a row around an annular rib is divided in the circumferential direction, and a segment sprocket having a plurality of teeth is forged and formed. In the device, a forging die for a tooth surface having no draft in the tooth width direction, which forms a tooth profile by abutting against a segment sprocket semi-finished product from the tip end side of a sprocket tooth, and a segment
And a forging die for an end face having no draft in the tooth width direction, which abuts on the semifinished product of the segment sprocket from the split face side of the sprocket and finish-molds the split face. According to the fifth aspect of the present invention described above, the draft angle remaining on the tooth surface of the roughly finished segment sprocket is corrected and removed by forging, and at the same time, the end face (the surface divided into segments) of the segment sprocket is removed. ) Is corrected to the desired shape and dimensions to eliminate the necessity of finishing the end face by machining after forging, and a high-quality segment / sprocket can be manufactured at low cost.

According to a sixth aspect of the present invention, in addition to the configuration of the fifth aspect of the invention, the tooth surface forging die is provided in a plurality along the plane passing through the center line of the annular rib. Each of the divided tooth surface forging dies, which is divided and has the above-mentioned divided tooth surface forging die, has means for pressing the annular rib toward the center in the radial direction, and has a draft angle with respect to the tooth profile surface. It is characterized by being. Claim 6 described above.
According to the invention of the present invention, the forging die of the tooth profile surface of the semi-finished segment sprocket is provided with a draft angle in the longitudinal direction, the end face of the semi-finished segment sprocket is forged, and the segment having a large number of teeth is formed. The three functional requirements of constructing a sprocket can be fulfilled without interfering with each other. That is, it is advantageous in terms of strength and the like to reduce the number of divided sprockets into segments and increase the number of teeth per one. However, the segment
If the number of teeth per sprocket is large, a draft in the opposite direction to the sprocket tooth surface is likely to occur in vertical forging. According to the sixth aspect of the present invention, since the tooth surface forging die is divided and each is pressed in the radial direction, a reverse gradient of the tooth surface does not occur and a forward draft angle can be provided. Further, since the end face mold is further provided, it is possible to simultaneously forge and finish the end faces of the semi-finished segment sprocket.

According to a seventh aspect of the present invention, in addition to the configuration of the sixth aspect of the present invention, the segment / sprocket semi-finished product further includes an inner surface of the semi-finished annular spigot facing the inside of the annular rib. And a base forging die having a mold surface having a small radius of curvature, and a semi-finished segment sprocket having a toroidal rib portion having a radius of curvature larger than the target shape can be pressed to finish-mold to a target shape radius of curvature. It is characterized by the following. According to the seventh aspect of the present invention described above, the draft of the sprocket tooth surface is set by correcting the semifinished product of the segment sprocket having a larger radius of curvature of the annular rib than the target shape to the radius of curvature of the target shape by finish forging. In addition, the forging of the end face of the semi-finished segment sprocket can be performed in the same process.

According to an eighth aspect of the present invention, in addition to the configuration of the fifth to seventh aspects of the present invention, the semi-finished product of the segment sprocket is mounted on the base forging die with the sides substantially leveled. And an upper die that forges the side surface into a laterally-pressed shape, and the upper die and the forging die for an end face come into contact with each other through a slope. When the die is pressed down, the force in the pressing-down direction is transmitted to the end surface forging die via the slope, and the upper die acts as a cam drive member, and the end surface forging die acts as a cam driven member, and the above-mentioned cam is driven. The function is such that the forging die for the end face is pressed against the division surface of the semi-finished product of the segment and sprocket in the tangential direction of the annular rib. According to the eighth aspect of the present invention described above, if the driving means for pressing the upper die toward the base forging die is provided, it is not necessary to provide the driving means for the end face forging die. That is, when the upper die is lowered, the forging die for the end surface which comes into contact with the upper die through the slope is pressed by the cam function toward the end surface of the semi-finished product of the segment sprocket, and the pressing force presses the end surface to the final forging pressure. Is done. If a driving force in the pressing direction can be applied to the end surface forging die by the above-described action, the end surface forging die can be reciprocated by taking appropriate means such as attaching a return spring. Further, when a pair of end face forging dies are pressed and driven by one upper mold, the pair of end face forging dies perform forging pressure operations in synchronization with each other, and each of the pair of end face forging dies is pressed. The pressure almost cancels each other, and the external force applied to the semifinished segment sprocket almost balances in the tangential direction of the annular rib, so that the finish forging can be performed in a stable state and the product accuracy can be improved. It is valid.

The structure of the apparatus according to the ninth aspect of the present invention is the same as that of the eighth aspect.
In addition to the configuration of the apparatus of the invention, the upper die has a slope that slides on the tooth surface forging die and drives the tooth surface forging die in the radial direction, and the radial driving force that meshes with the base forging die. And a pair of end face forging dies are arranged opposite to both ends of the semi-finished segment sprocket to oppose each other. The forging pressures of the end face forging dies face each other, so that the forging pressure component forces in the direction in which the two end face forging dies face each other are balanced. According to the ninth aspect of the present invention described above, the forging pressure applied to the semifinished segment sprocket and the reaction force thereof are balanced, and the biased external force on the semifinished segment sprocket is significantly reduced. That is, the reaction force applied by the upper die pressing and driving the tooth surface forging die is supported by the reaction force bearing surface, and the forging pressure reaction force in the radial direction is almost completely canceled. Similarly, the radial forces experienced by the base forging die are almost completely canceled. Regarding the force received by the base forging die from the pair of end face forging dies and the force received by the segment sprocket semi-finished product from the pair of end face forging dies, the direction in which the pair of end face forging dies are opposed to each other Are completely canceled out, but the component in a direction different from the above-described component in the opposite direction is not canceled out. However, since the non-cancelling component force is small compared to the whole forging pressure, there is no possibility that the accuracy of the forging finish is adversely affected.

According to a tenth aspect of the present invention, in addition to the eighth or ninth aspect of the present invention, the end surface forging die is formed by two guide rods tangential to the annular rib. The forging die for an end face is guided by a return spring which is guided in the tangential direction with respect to the base forging die and is disposed between the two guide rods.
An elastic restoring force is provided in a direction away from the sprocket. Claim 1 described above
According to the invention of No. 0, the forging die for the end face abuts on the end face of the segment sprocket at the right position at the right angle, and the end face forging with high precision can be performed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an apparatus for finishing and forging a segment sprocket constructed for carrying out the method for producing a segment sprocket according to the present invention, and FIG. 1 (A) is a schematic plan view. (B) is a sectional view of a forging die for an end surface of the forging device and an accessory member thereof. The reference numeral 12 designates a semi-finished semifinished segment sprocket, the details of which will be described later in detail with reference to FIG. Reference numeral 4 denotes a base forging die (abbreviated to a base die if it is not confusing), on which the segment sprocket semi-finished product 12 is mounted. An upper mold 15 is arranged so as to cover it. This figure 1
In (A), the members covered by the upper mold 15 do not appear in appearance, but the figure is schematically illustrated for easy reading, and hidden members are also drawn by solid lines. (The same applies to FIGS. 2, 5, and 6 described later.) In FIG. 1A which depicts a plan view, the periphery of the semifinished product of the segment sprocket 12 is surrounded by a forging die as described below. As described later, it is tightened from the surroundings and finish forged.

A forging mold for the tooth surface (abbreviated as a tooth surface mold if not confusing) is arranged opposite to the sprocket teeth side of the semifinished segment sprocket product 12. The tooth surface type of the present embodiment includes a tooth surface type
It is divided into Otsu6. In this way, when the tooth surface mold is divided into a plurality of parts and each is pressed in the radial direction of the arc-shaped rib, a draft in the opposite direction occurs on the tooth surface even if the number of teeth of the semi-finished segment sprocket is large. Not to be.
The mechanism for driving the tooth surface molds 5 and 5 in the forging direction and the mechanism for restoring them in the direction opposite to the forging direction will be described later in detail with reference to FIGS. In FIG. 1A, a guide rod 10 and a return spring 11 for guiding the tooth surface mold in the radial direction are shown, and these will be described later in detail with reference to FIGS. Since the terms of the radial direction and the tangential direction are used to represent the forging direction in the present invention, it is noted that the product to be manufactured in the present invention is the arc-shaped segment sprocket 2 shown in FIG. This member is formed by dividing the annular sprocket shown in FIG. 7 into an arc shape. The radial direction and the tangential direction in the present invention mean the radial direction and the tangential direction of the arcuate rib 2z, respectively, as shown in FIG. 8, but the radial direction and the tangential direction of the annular rib 1z of the sprocket shown in FIG. It is essentially the same as the tangential direction.

A forging die for an end surface (abbreviated as an end surface type if it is not confusing) 7 is arranged opposite to both end surfaces of the semi-finished segment sprocket 12.
The two guide rods 8 are slidably guided in a tangential direction, and an elastic restoring force is applied by a return spring 9 in a direction away from the semi-finished segment sprocket 12. FIG. 1B shows a mechanism for driving the end face mold 7 in the forging direction. The end mold 7 has a slope 7a, and the upper mold 15 has an end-type drive slope 15a correspondingly. As a result, when the upper die 15 is pressed toward the base die 4, the side surface of the semi-finished product of the segment sprocket is finish-forged to improve the dimensional accuracy of the side surface and the surface roughness of the side surface. Then, a component force for driving the end face mold 7 in the forging direction via the slope is generated, and the dimensional accuracy and the surface roughness of the end face are finished as predetermined at the same time as the side faces. In FIG. 1 (B), the segment sprocket 12 is hidden by the tooth surface type / instep 5. The width direction of the sprocket teeth is a direction indicated by an arrow in FIG. (B) and a direction perpendicular to the paper surface in FIG. The tooth surface molds A and 5 have no draft in the tooth width direction. For this reason, even if a draft in the tooth width direction remains in the semi-finished segment sprocket semi-finished product, it is corrected to exclude the finish forging. The reason why the tooth surface mold of the present invention does not require a draft angle in the tooth width direction is that it is configured to be vertically forged as easily understood from FIG.

FIG. 2 shows a state in which the semi-finished product of the segment sprocket is subjected to finish forging by the forging apparatus shown in FIG. A) is a schematic plan view,
(B) is sectional drawing of the forging die for end surfaces, and its attached member. In comparison with FIG. 1 described above, in FIG. 2, it can be seen that the end face mold 7 is driven by the upper mold 15 and is brought into close contact with the end face of the segment sprocket. Next, the state in which the semi-finished product of the segment sprocket is forged by the above-described forging apparatus will be described. FIG.
Shows a semifinished product of a segment sprocket, (A) is a plan view, and (B) is a BB cross-sectional view thereof. The semi-finished product of the segment sprocket of this example is hot stamped and forged in a direction shown by an arrow in FIG. 8B by a horizontal striking method, and burrs 12a and 12b are generated and a draft 12c is formed. , 12d, and 12e remain. In this example, the radius of the arc-shaped rib is formed larger by ΔR than the radius R of the target shape. However, when the present invention is implemented, the radius of the semi-finished product is changed to the radius R of the target shape. It is also possible to keep it equal to The reason is that, as described with reference to FIGS. 1 and 2, the tooth surface mold is divided into two parts, the former and the latter, so that even if the semi-finished product has the same radial dimension as the target dimension R, uniform tooth surface forging pressure is possible. This is because the.

FIGS. 4A and 4B show a forged finished product of a segment sprocket, which is an object to be manufactured. FIG. 4A is a plan view in which a radial dimension and a cutting symbol are added, and FIG. It is a sectional arrow view. The segment shown in FIG.
The burrs of the semi-finished sprocket 12 are trimmed and removed, heated to the forging temperature, and placed on the base mold 4 as shown in FIG. FIG. 5 shows the segment and sprocket forging device in the operating state shown in FIG. 1 described above. FIG. 5A is a plan view similar to FIG. 1A, and FIG. FIG. 4 is a cross-sectional view taken along a line B ″ -B ″. As understood with reference to FIGS. 5A and 5B, the tooth surface mold / instep 5 is pressed to the left in the figure by the tooth surface type driving slope 15 b of the upper mold 15. The base mold 4 also receives the leftward pressing force, and at the same time, the upper mold 15 receives a rightward reaction force. Then, the reaction force bearing surface 15c of the upper mold 15 meshes with the base mold 4 and is balanced by receiving the above reaction force. In this way, since the radial forces applied to the base mold 4 are balanced, forging can be performed in a stable state. FIG. 6 shows the segment sprocket forging device in the operating state shown in FIG. 2 described above, and FIG.
FIG. 6A is a plan view similar to FIG. 2A, and FIG. 6B is a cross-sectional view taken along the line B "-B". 4 is a pusher for pushing up the forged segment sprocket 13 and removing it from the base mold 4. Segment sprocket 13 removed after forging finish
Becomes the object shape is forged finish its end face, so satisfies the dimensions accuracy and surface roughness specified in engineering drawings, bolt holes for mounting (code 2 _H in FIG. 9)
The finished product can be obtained simply by drilling.

[0022]

As described above, according to the embodiment of the present invention, the structure and function of the semi-finished segment / sprocket semi-finished product remain on the tooth surface. The draft angle is corrected with a tooth surface forging die to remove the draft angle, and the forging die is pressed against the end surface of the semi-finished segment sprocket to finish forging to the target shape, so the end surface is machined after forging No need to do. For this reason, compared to the forging method of the segment sprocket according to the known invention, machining of the end face after forging becomes unnecessary without increasing the forging process, and the manufacturing cost can be reduced without lowering the product quality. it can.

According to the second aspect of the present invention, when a sprocket is divided into segments to form a segment sprocket, the number of divisions is reduced, and one segment
Even if the number of sprocket teeth formed on the sprocket is relatively large, it is possible to prevent the occurrence of a reverse draft in vertical forging of the sprocket teeth. That is, without impeding the configuration of the known invention, and without impairing the effects of the known invention, and without increasing the number of forging steps of the known invention, the present invention is applied to the end face machining after forging. Is unnecessary, and a high quality segment sprocket can be manufactured at lower cost.

According to the third aspect of the present invention, the "plastic deformation in which the radius of the annular rib is reduced to increase the curvature" in the second aspect of the present invention can be easily and reliably performed. The degree of draft freedom of the sprocket tooth surface in the finish forging has a large degree of design freedom, and the mold separation at the end of the finish forging can be improved.

According to the fourth aspect of the present invention, even if the sprocket teeth do not have sufficient dimensional accuracy at the time of rough finishing or the surface roughness of the side surfaces is not good, the tooth surfaces and the end surfaces can be corrected. At the same time as the forging, the side surface is forged, and all the outer peripheral surfaces of the segment sprocket are finished to the target shape (dimensions and surface roughness) in the same process.

According to the fifth aspect of the present invention, draft angle remaining on the tooth surface of the roughly finished segment sprocket is corrected and removed by forging, and at the same time, the end surface of the segment sprocket (the surface divided into segments). Can be modified to the desired shape and dimensions to eliminate the necessity of finishing the end face by machining after forging, and a high-quality segment sprocket can be manufactured at low cost.

According to the sixth aspect of the present invention, the forging die for the tooth profile surface of the semi-finished segment sprocket is provided with a draft angle in the longitudinal direction, and the end face of the semi-finished segment sprocket is finish forged. The three functional requirements of constructing a segment sprocket with a large number of teeth can be fulfilled without interfering with each other. That is, it is advantageous in terms of strength and the like to reduce the number of divided sprockets into segments and increase the number of teeth per one.
However, if the number of teeth per segment sprocket is large, a draft angle in the opposite direction is likely to be generated on the sprocket tooth surface during vertical forging. According to the sixth aspect of the present invention, since the tooth surface forging die is divided and each is pressed in the radial direction, a reverse gradient of the tooth surface does not occur and a forward draft angle can be provided. Further, since the end face mold is further provided, it is possible to simultaneously forge and finish the end faces of the semi-finished segment sprocket.

According to the seventh aspect of the present invention, the draft of the sprocket tooth surface is set by correcting the semi-finished product of the segment sprocket having a larger radius of curvature of the annular rib than the target shape to the radius of curvature of the target shape by finish forging. In addition to making it easier, the forging of the end face of the semi-finished segment sprocket can be performed in the same process.

According to the invention of claim 8, if the driving means for pressing the upper die toward the base forging die is provided, it is not necessary to provide the driving means for the end face forging die. That is, when the upper die is lowered, the forging die for the end surface which comes into contact with the upper die through the slope is pressed by the cam function toward the end surface of the semi-finished product of the segment sprocket, and the pressing force presses the end surface to the final forging pressure. Is done. If it is possible to apply a driving force in the pressing direction to the end surface forging die by the above action,
By taking appropriate measures such as attaching a return spring, the end surface forging die can be reciprocated. Further, when a pair of end face forging dies are pressed and driven by one upper mold, the pair of end face forging dies perform forging pressure operations in synchronization with each other, and each of the pair of end face forging dies is pressed. The pressure almost cancels each other, and the external force applied to the semifinished segment sprocket almost balances in the tangential direction of the annular rib, so that the finish forging can be performed in a stable state and the product accuracy can be improved. It is valid.

According to the ninth aspect of the present invention, the forging pressure applied to the semi-finished segment sprocket and the reaction force thereof are balanced, and the biased external force on the semi-finished segment sprocket is remarkably reduced. That is, the reaction force applied by the upper die pressing and driving the tooth surface forging die is supported by the reaction force bearing surface, and the forging pressure reaction force in the radial direction is almost completely canceled. Similarly, the radial forces experienced by the base forging die are almost completely canceled. Regarding the force received by the base forging die from the pair of end face forging dies and the force received by the segment sprocket semi-finished product from the pair of end face forging dies, the direction in which the pair of end face forging dies are opposed to each other Are completely canceled out, but the component in a direction different from the above-described component in the opposite direction is not canceled out. However, since the non-cancelling component force is small compared to the whole forging pressure, there is no possibility that the accuracy of the forging finish is adversely affected.

According to the tenth aspect of the present invention, the forging die for the end face abuts on the end face of the segment sprocket at the right position at the right angle, and the end face forging can be performed with high precision.

[Brief description of the drawings]

FIG. 1 shows an apparatus for finish forging of a segment sprocket configured to carry out the method for manufacturing a segment sprocket of the present invention, (A) is a schematic plan view, and (B) is the above-described forging. FIG. 2 is a sectional view of a forging die for an end face of a device for use and an accessory member thereof.

FIG. 2 shows a state in which the forging device shown in FIG. 1 described above is operated, and the semi-finished product of the segment sprocket is subjected to finish forging to become a segment sprocket of a finished product. FIG. 2B is a schematic plan view, and FIG. 2B is a cross-sectional view of a forging die for an end surface and its attached members.

FIG. 3 shows a semi-finished product of a segment and a sprocket;
(A) is a plan view, and (B) is a BB sectional view thereof.

4A and 4B show a forged finished product of a segment sprocket which is an object to be manufactured. FIG. 4A is a plan view in which a radius dimension and a cutting symbol are added to a plan view, and FIG. FIG.

5 shows the segment and sprocket forging device in the operating state shown in FIG. 1, and FIG. 5 (A) is a plan view similar to FIG. 1 (A), and FIG. 5 (B). Is B ″
-B "is a sectional view taken along the arrow.

FIG. 6 shows the segment and sprocket forging device in the operating state shown in FIG. 2, and FIG. 6 (A) is a plan view similar to FIG. 2 (A), and FIG. 6 (B). Is B ″
-B "is a sectional view taken along the arrow.

FIG. 7 is a front view showing an example of a sprocket in which 25 teeth are formed around a rib.

FIG. 8 shows a five-tooth segment formed by dividing the 25-tooth sprocket illustrated in FIG. 7 above into five equal parts in the circumferential direction.
FIG. 3 is an explanatory diagram schematically illustrating an example of a sprocket.

FIG. 9 is a view for explaining a vertical forging method of a segment sprocket, in which an arrow indicating a forging direction is added to a front view of the five-tooth segment sprocket.

FIG. 10 is a view for explaining a technical problem when the segment sprocket shown in FIG. 9 described above is vertically forged, and is a view in which an auxiliary line is added to a front view of the segment sprocket.

FIG. 11 is a front view of a segment sprocket with an auxiliary line indicating a forging direction and an auxiliary line indicating a draft angle, showing one embodiment of a forging method of a segment sprocket according to a known invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Sprocket, 1a-1y ... Sprocket teeth, 2
... segment sprocket teeth 2a to 2e ... sprocket, ribs 2 _H ... bolt hole, 2z ... annular (circular arc shape), 3 ... semi-finished products segment sprocket, 4 ... base forging die (abbreviated-base type) , 5 ... Forging die for tooth surface (abbreviation / tooth surface type) ・ A, 6 ... Forging die for tooth surface (abbreviation / tooth surface type) ・
Otsu, 7: Forging die for end face (abbreviation / end face type), 8: Guide rod, 9: Return spring, 10: Guide rod, 11
... Return spring, 12 ... Segment sprocket semi-finished product, 12a, 12b ... Burr, 12c, 12d, 12e
... draft angle, 12f tooth bottom, 13 ... segment sprocket, 13a ... tooth tip, 13b ... tooth bottom, 13c ... flange-shaped part, 14 ... pusher, 15 ... upper mold, 15a ... tooth surface type driving slope, 15b ... Tooth surface drive slope, 15c: reaction force bearing surface, R: radius dimension of arc-shaped rib, t: tangent drawn to sprocket teeth, θ: forward draft angle, φ: reverse draft angle.

Claims (10)

[Claims] 1. A method of forging and forming a segment sprocket having a plurality of teeth, which is obtained by dividing a sprocket having teeth arranged around an annular rib in a circumferential direction, and forging the sprocket. Roughly finish the semi-finished segment sprocket with a draft on the surface, apply a forging die for the tooth surface to the tooth surface of the semi-finished segment sprocket, press hot, and form on the sprocket tooth surface In addition to plastic deformation so as to eliminate the draft angle, the segment sprocket is applied with a forging die for the end face to the divided surface divided in the circumferential direction, and pressed in the tangential direction to perform plastic deformation. Producing a semi-finished product of the segment sprocket in a desired shape. 2. A semi-finished segment sprocket having a shape in which the radius of the annular rib is reduced by increasing the radius of the annular rib compared to the segment sprocket having the target shape is roughly finished by hot forging and trimmed. After that, the forging die for the tooth surface is subjected to a correction finish for removing draft, and in the same process as the forging die for the tooth surface, the radius of the annular rib is reduced to increase the curvature. 2. The method for producing a segment sprocket according to claim 1, wherein the forging is finished to a target shape by plastic deformation. 3. A method in which a plurality of circumferentially divided tooth surface forging dies are applied to the semifinished segment sprocket, and the plurality of divided tooth surface forging dies are pressed in respective radial directions. The method for manufacturing a segment sprocket according to claim 2, characterized in that: 4. The semi-finished product of the segment and sprocket is simultaneously traversed by a forging die through a forging die, simultaneously with the finishing of the draft removal by the forging die for the tooth surface and the finishing of the divided surface by the forging die for the end surface. 2. The method according to claim 1, wherein the side surfaces of the sprocket teeth are finished by applying a forging pressure of? 5. An apparatus for forging and forming a segment sprocket having a plurality of teeth, which is obtained by dividing a sprocket in which teeth are arranged around an annular rib in a circumferential direction. A forging die for tooth surfaces that does not have a draft angle in the width direction of the teeth, which makes contact with the semi-finished product of the segment sprocket from the side, and does not have a draft angle in the tooth width direction. An apparatus for manufacturing a segment and sprocket, comprising: a forging die for an end face having no draft in a tooth width direction, which finish-molds the divided surface in contact with a product. 6. The tooth surface forging die is divided into a plurality of parts along a plane passing through the center line of the annular rib, and each of the divided tooth surface forging die is 6. The segment according to claim 5, further comprising means for pressing the annular rib toward the center in the radial direction, and having a draft with respect to the tooth profile.
Equipment for manufacturing sprockets. 7. A base forging die having a mold surface facing the inside of the annular rib of the segment sprocket semi-finished product and having a radius of curvature smaller than that of the inner surface of the semi-finished annular rib. 7. The segment as claimed in claim 6, wherein the semifinished product of the segment and sprocket, in which the radius of curvature of the annular rib portion is larger than the target shape, can be pressed so as to finish-mold to the target shape. Equipment for manufacturing sprockets. 8. An upper die for flattening the side surface of the semi-finished segment sprocket placed on the base forging die while substantially leveling the side surface thereof, and forging the side surface of the semi-finished product into a horizontal striking shape, and The upper die and the end surface forging die are in contact with each other via a slope, and when the upper die is pressed down, the force in the pressing direction is transmitted to the end surface forging die through the slope. The upper die acts as a cam drive member and the forging die for the end surface acts as a driven member for the cam, and the forging die for the end surface is moved by the above-described cam function to the divided surface of the semifinished product of the segment and sprocket. 8. The apparatus for manufacturing a segment sprocket according to claim 5, wherein the apparatus is adapted to be tangentially pressed. 9. The upper mold has a slope that slides on and drives the tooth surface forging die in the radial direction and a reaction force of the radial driving force that meshes with the base forging die. A counterforce bearing surface is formed to be supported and balanced, and the forging dies for the end faces are arranged as a pair facing each end of the semi-finished segment sprocket, and a pair of forging dies for the end faces are provided. 9. The forging and sprocket production according to claim 8, wherein the forging pressures of the two end face forging dies are opposite to each other so that the forging force components in the direction in which the two end face forging dies are opposed to each other. Equipment. 10. The end face forging die is guided in a tangential direction with respect to a base forging die by two guide rods tangential to the annular rib, and the two guides are provided. 10. The forging die for an end face is provided with an elastic restoring force in a direction away from the segment sprocket by a return spring disposed between the rods, according to claim 8 or claim 9. Equipment for manufacturing segments and sprockets.