JP2013166157A - Rocking die forging method, workpiece used therefor and method for determination of workpiece shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance inner diameter accuracy of an inner circumferential surface of a cylindrical part when forming a disk-like component having a cylindrical part on its center by a rocking die forging method.SOLUTION: A stress which causes a material of a workpiece W flow is generated by abutting a workpiece W set in a lower mold 14 on an upper mold 12 and by pressurizing the workpiece W. The stress generated in the workpiece W at this time becomes large for approaching an end part facing the upper mold. A shape within a predetermined range of a center hole Wb in an axial direction of the workpiece W before a rocking die forging process is formed with its diameter gradually larger as it approaches the end part side facing the upper mold 12 in a state that the workpiece W is set in the lower mold 14. The shape of the workpiece W is adjusted in such a manner that as it approaches the end part side facing the upper mold 12, the material amount in the periphery of the center hole Wb is further reduced so that the material flowing to an inner circumferential surface of a cylindrical part does not become excessive. The material amount in the periphery of the center hole Wb is previously reduced so that the flowing amount does not become excessive by previously anticipating the material flowing to the inner circumferential surface of the cylindrical part.

Description

  The present invention relates to a swing forging method, a workpiece used therefor, and a workpiece shape determination method.

Conventionally, a swing forging method has been employed as a method for forming a disk-shaped part. The rocking forging device used in this rocking forging method has, for example, a conical upper angle mold and a lower mold facing the upper mold. In addition, it includes a swinging portion for swinging and rotating the so-called upper center with respect to a predetermined center point (so-called “grinding motion”), and an elevating portion for separating and approaching the upper die and the lower die. is there.

The specific forming procedure using this swing forging device is as follows. First, a cylindrical workpiece is set in the lower mold in the mold open state, and the upper mold and the lower mold are brought close to each other to swing and rotate. The work is brought into contact with the upper mold. As the upper mold swings and rotates, the workpiece molding proceeds sequentially in the circumferential direction. As the molding of the workpiece progresses, the vertical distance between the upper mold and the lower mold approaches and is held at a constant distance. After the upper mold and the lower mold are held at a fixed distance, the upper mold and the lower mold are separated from each other after the workpiece is held for a predetermined time while the upper mold continues to rotate and rotate. To do. According to such a swing forging method, impact and vibration are less generated than in a general forging method, and the internal stress of the work can be reduced, so that the final product shape can be forged in one cycle. (For example, see Patent Documents 1 and 2).

JP 2005-211902 A JP 61-242738 A

However, when forming a disk-shaped part having a cylindrical portion at the center, such as a CVT sheave, by the conventional swing forging method, the inner peripheral surface of the cylindrical portion becomes insufficiently constrained. There is a possibility that the material flow will be excessive and the inner diameter accuracy will be impaired.
The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an inner peripheral surface of a cylindrical portion when a disk-shaped part having a cylindrical portion at the center is formed by a swing forging method. This is to increase the accuracy of the inner diameter.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) A first die having an angle in a conical shape is swung and rotated with a predetermined center point as a reference, and a disk-shaped workpiece having a center hole is formed on a second die that is opposed to the first die in the axial direction. A swing forging method for forming the workpiece by setting the first die and the second die apart from each other and bringing the workpiece into contact with the first die, before the swing forging step. The shape of the work in a predetermined range in the axial direction of the center hole is formed so that the diameter increases as it goes toward the end facing the first mold with the work set in the second mold. Dynamic forging method (Claim 1).

In the swing forging method described in this section, for example, the first die moves up and down with respect to the second die in a state where the first die having a conical angle is driven to swing and rotate with reference to a predetermined center point. By doing so, the first mold and the second mold are separated and approached. Further, the first mold is lowered while the work before the swing forging process is set in the second mold, and the work is brought into contact with the first mold that is swung and rotated. With the rotational movement, the molding of the workpiece set in the second mold is sequentially advanced in the circumferential direction.

The stress that causes the material flow of the work is generated when the work set in the second mold comes into contact with the first mold and the work is pressed. At this time, the stress generated in the work is The closer to the end facing the type 1, the larger. Therefore, in the invention of this section, the shape of the predetermined range in the axial direction of the center hole of the work before the swing forging process is set to the end side facing the first mold with the work set in the second mold. The shape of the workpiece is adjusted so that the material flow to the inner peripheral surface of the cylindrical portion does not become excessive by forming it so as to increase in diameter as it goes. That is, in the swing forging method of this section, the material flow to the inner peripheral surface of the cylindrical portion is anticipated in advance, and the swing is performed in order to reduce the amount of material in the periphery of the center hole in advance so that the flow amount is not excessive. The shape in a predetermined range in the axial direction of the center hole of the work before the forging process is adjusted.

(2) In the above item (1), a predetermined range in the axial direction formed so as to expand the center hole of the workpiece is determined by the load applied to the workpiece from the first mold and the second mold. An oscillating forging method in which a stress sufficient to cause plastic deformation is generated in the workpiece (claim 2).
In the swing forging method described in this section, in order to achieve the operation described in the above item (1), the range in which the center hole of the workpiece is formed to be enlarged is defined as the predetermined range in the axial direction with the first die and the second mold. A load is applied to the workpiece by the mold, and the stress is generated in a range that causes plastic deformation in the workpiece. Here, the range in which a stress sufficient to cause plastic deformation in the workpiece is expanded from the end side facing the first mold of the workpiece to the deep portion, but the stress tends to decrease as the depth increases. For this reason, the amount of flow of the material also tends to decrease as the depth of the workpiece. Further, with the progress of the swing forging process, the amount of flow of the material tends to decrease as the plastic deformation of the workpiece progresses. Therefore, the shape of the work in the range where stress sufficient to cause plastic deformation occurs before the rocking forging process is expanded toward the end facing the first mold in a state where the work is set in the second mold. It is formed so as to have a diameter. And as it goes to the end side facing the first mold, the amount of material around the center hole is further reduced, and the material flow to the inner peripheral surface of the cylindrical portion is made regardless of the progress of the swing forging process. The workpiece shape is adjusted in advance so as not to become excessive.

(3) In the above (1) and (2), the swing forging method for determining the shape of a predetermined range in the axial direction of the center hole of the workpiece according to the approaching operation pattern of the first die and the second die (Claim 3).
In swing forging, the approach pattern of the first mold and the second mold differs depending on what is important (target) such as dimensional accuracy and machining efficiency in the machining process. Therefore, the swing forging method described in this section determines the shape of the predetermined range in the axial direction of the center hole of the workpiece according to the approaching operation patterns of the first die and the second die, and thereby the first die and the first die. Regardless of the type 2 approach movement pattern, the amount of flow of material to the inner peripheral surface of the cylindrical portion is prevented from becoming excessive. By the way, the stress generated in the workpiece increases as the speed of the first and second type approaching operations (die feeding speed) increases, and the range extends to the deep part. For this reason, the shape of each part in the predetermined range in the axial direction of the center hole of the workpiece is determined in consideration of the die feed speed and the progress of the swing forging process.

(4) In the above item (3), the approach movement patterns of the first mold and the second mold are adjusted so that the load applied to the workpiece by the first mold and the second mold is constant. Swing forging method. (Claim 4).
In the swing forging method described in this section, the approach movement patterns of the first die and the second die are adjusted so that the load applied to the workpiece by the first die and the second die is constant. By doing so, the die feed speed is fast at the beginning of the swing forging forming and is slow at the end of forming. For this reason, the state of stress that causes plastic deformation changes with the progress of swing forging, and the aspect of material flow to the inner peripheral surface of the cylindrical portion of the workpiece becomes complicated. In the swing forging method described in this section, such a complicated material flow is anticipated in advance, and the swing forging is performed in order to reduce the amount of material around the center hole in advance so that the flow amount is not excessive. The shape of a predetermined range in the axial direction of the center hole of the workpiece before the process is adjusted.

(5) A workpiece before the rocking forging step used in the rocking forging method described in (1) to (4) above,
A predetermined range in the axial direction of the central hole in the state set in the second mold has a shape that increases in diameter toward the first mold side, and the shape of the central hole is
With respect to the test workpiece obtained by simplifying the shape of the workpiece before the swing forging process, swing forging is performed on the test workpiece under different approach movement patterns of the first die and the second die. The shape of the center hole of the test workpiece after rocking forging for each approach movement pattern is made into a database, and based on the database, the material flow generated in the workpiece before the rocking forging process is predicted, and the material flow A work that is determined based on the prediction (claim 5).

The workpiece before the rocking forging process described in this section has a shape in which the predetermined range in the axial direction of the center hole is expanded in diameter as it is set in the second die toward the first die. Is. The shape of the center hole is determined by the following procedure. That is, with respect to the test workpiece in which the shape of the workpiece before the swing forging process is simplified, the material flow according to the approach operation pattern of the first die and the second die is generated, Create a database of shapes after rocking forging of the center hole of the workpiece. Based on this database, the rock forging process predicts the material flow according to the approaching pattern of the first die and the second die of the work before the rock forging process used in the actual rock forging. The shape of a predetermined range in the axial direction of the center hole of the previous workpiece is determined.
By performing the swing forging using the workpiece before the swing forging step, the effects of the above items (1) to (4) are exhibited.

(6) A method for determining the shape of a workpiece before the rocking forging process used in the rocking forging method described in (1) to (4) above,
A test workpiece obtained by simplifying the shape of the workpiece before the rocking forging process is set in the second die, and the test workpiece is subjected to different approaching operation patterns of the first die and the second die. Perform swing forging, create a database of the shape of the center hole of the test workpiece after swing forging for each approach movement pattern, and based on the database, the material flow generated in the workpiece before the swing forging process The shape of the workpiece that predicts and determines the shape of the workpiece before the rocking forging step that expands in diameter toward the first die in a predetermined range in the axial direction of the center hole based on the prediction of the material flow Determination method (Claim 6).

The method for determining the shape of the workpiece before the swing forging step described in this section is based on the approaching pattern of the first die and the second die with respect to the test workpiece obtained by simplifying the shape of the workpiece before the swing forging step. The material flow according to the condition is generated, and the shape after the rocking forging of the center hole of the test workpiece for each approach movement pattern is made into a database. Based on this database related to the test workpiece, the material flow according to the approaching pattern of the first die and the second die of the workpiece before the swing forging process used for actual swing forging is predicted. Thus, the shape of a predetermined range in the axial direction of the center hole of the workpiece before the swing forging process is determined.
By performing the swing forging using the workpiece before the swing forging step, the effects of the above items (1) to (4) are exhibited.

  Since this invention was comprised in this way, it becomes possible to raise the internal-diameter precision of a cylindrical part inner peripheral surface at the time of shape | molding the disk-shaped component which has a cylindrical part in a center part by the rocking forging method.

It is principal part sectional drawing of the rocking forge apparatus used for the rocking forge method which concerns on embodiment of this invention. It is sectional drawing of the workpiece | work before the rocking forge process used for the rocking forge method which concerns on embodiment of this invention. It is a cross-sectional schematic diagram which shows the stress which arises in a workpiece | work at the time of rocking forge. It is a flowchart which shows the shape determination method of the workpiece | work before the rocking forge process used for the rocking forging method which concerns on embodiment of this invention. It is the figure which showed typically the procedure which determines the shape of the workpiece | work before a rocking forge process based on the method of FIG. 4, and performs rocking forging.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the following description, parts that are the same as or correspond to those in the prior art are assigned the same reference numerals, and detailed descriptions thereof are omitted.

In FIG. 1, the principal part of the rocking forging apparatus 10 used for the rocking forging method which concerns on embodiment of this invention is shown with the cross section. The swing forging device 10 includes a swing portion 16 that holds an upper die 12 and a fixed portion 18 that holds a lower die 14 as a second die. In this embodiment, the swinging part 16 holds the upper mold 12 as the first mold, and swings and rotates the upper mold 12 with reference to a predetermined center point. In the present embodiment, the swinging portion 16 also serves as an elevating portion, and moves the upper mold 12 up and down relative to the lower mold 14 so that the workpiece W comes into contact with the upper mold 12. On the other hand, the lower mold | type 14 sets the workpiece | work W which has the cylindrical part Wa (refer FIG. 8).

FIG. 1 shows two states of the swinging portion 16 and the fixed portion 18 (before forming and during forming). Further, as described above, the swinging portion 16 moves so as to move up and down with respect to the fixed portion 18, so that the lower die 14 is raised and the workpiece W is abutted against the upper die 12 that swings and rotates. Alternatively, a configuration in which the fixed portion 18 moves up and down may be provided with respect to the swinging portion 16 by providing the fixed portion 18 with a lifting function. The approach control pattern of the upper die 12 and the lower die 14 (setting and increasing / decreasing the die feed speed) depends on what is important in the swing forging process (target), and the main control device of the swing forging device 10 Thus, it can be set as appropriate.

FIG. 2 shows a workpiece W before the swing forging process, which is used in the swing forging method according to the embodiment of the present invention. The workpiece W is a disc-shaped material having a cylindrical portion Wa at the center, and is formed from a simple columnar material by an appropriate method such as hot forging or cold forging. Then, in a state where the center hole Wb of the cylindrical portion Wa of the workpiece W is set in the lower mold 14 (FIG. 1), the predetermined range VA in the axial direction of the center hole Wb is the upper mold 12 side (FIG. 1). It has a shape that increases in diameter as it goes to the upper side.
In the example shown in the drawing, the diameter of the center hole Wb is such that the opening diameter below the cylindrical portion Wa is the minimum diameter D0, and the diameter D1 <D2 <D3 <from the middle portion toward the upper side in FIG. The diameter is increased stepwise with D4, and the opening diameter of the end surface of the cone portion Wc is the maximum diameter D5. In the example shown in the figure, the center hole Wb has a mode in which the diameter gradually increases and gradually expands from the diameter D1 to the diameter D5, but is merely an example. The range VA for expanding the diameter and the degree of diameter expansion are appropriately determined according to the shape determining method described later. Moreover, the aspect which expands through a level | step difference may be employ | adopted as needed.

  FIG. 3 shows the stress generated in the workpiece W during the swing forging of the workpiece W using the swing forging device 10. In the figure, the stress in the range indicated by the symbol ML is a large stress that causes plastic deformation. On the other hand, the stress in the range indicated by the symbol MS is small and does not cause plastic deformation. That is, the range in which stress sufficient to cause plastic deformation occurs extends from the end surface side of the cone Wc, which is the end facing the upper mold 12 of the workpiece W, to the deep portion, but the stress decreases as the depth increases. There is a tendency. In addition, the present inventors have confirmed that the stress generated in the workpiece W increases as the speed of the approaching operation of the upper mold 12 and the lower mold 14, that is, the mold feed speed increases, and the range extends to the deep part. ing.

In view of the above points, the shape of the center hole Wb of the workpiece W shown in FIG. 2 is determined in consideration of the magnitude of the stress that causes the material flow of the workpiece W as shown in FIG. Specifically, this is based on the procedure shown in FIGS. Hereinafter, a method for determining the shape of the workpiece W will be described in order.
S100: First, a test workpiece W ₀ (see FIG. 5A) is prepared in which the shape of the workpiece W before the swing forging step used in actual swing forging is simplified. The test workpiece W ₀ is simplified in shape by making the diameter of the center hole W ₀ b constant in comparison with the workpiece W before the rocking forging process that is actually used in this mobile phone. Is. In addition, the shape of other parts is simplified as necessary.
S110: test workpiece W ₀ is set to the lower mold 14, different approach movement pattern under the upper mold 12 and the lower mold 14, for example, by a mold feeding speed is several pattern change, swing forging test workpiece W ₀ Is to implement. The center hole _W 0 b after molding (see FIG. 5 (b)), to confirm the inner diameter shape. The confirmation operation of the inner diameter shape is appropriately performed manually or using an automatic measuring instrument.

S120: From the result of confirming the shape after rocking forging for each approach movement pattern in the above step S110, when the center hole W ₀ b of the workpiece W ₀ has a certain approach action pattern, the center hole W after forming _To what extent the material flow F (see FIG. 5B) occurs in 0b is made into a database.
S130: Based on the database created in step S120, the material flow generated in the workpiece W before the swing forging process, which is used for actual machining, is predicted. Then, based on the prediction of the material flow, the inner diameter shape of the center hole Wb (see FIG. 5C) of the workpiece W that is actually subjected to the swing forging process and before the swing forging step is set. The workpiece W whose shape has been determined in this manner is set on the lower die 14 of the swing forging device 10 and the swing forging step is performed (see FIG. 5D).

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained.
First, according to the embodiment of the present invention, in a state where the workpiece W is set on the lower die 14 of the swing forging device 10, the upper die 12 is lowered to move the workpiece W relative to the upper die 12 that swings and rotates. As the upper mold 12 swings and rotates, the molding of the workpiece W set on the lower mold 14 proceeds sequentially in the circumferential direction.

The stress causing the material flow of the workpiece W is generated when the workpiece W set on the lower die 14 comes into contact with the upper die 12 and the workpiece W is pressurized. At this time, the stress is generated in the workpiece W. The stress increases as it approaches the end facing the upper mold (see symbols ML and MS in FIG. 3). Therefore, as shown in FIG. 2, the shape of the workpiece W before the swing forging process in the predetermined range VA in the axial direction of the center hole Wb is opposed to the upper die 12 with the workpiece W set on the lower die 14. It is formed so as to increase in diameter as it goes toward the end Wc. And as it goes to the end Wc side facing the upper mold 12, the amount of material around the central hole Wb is further reduced so that the material flow to the inner peripheral surface of the cylindrical portion Wa is not excessive. The shape of W is adjusted beforehand. That is, the work before the swing forging process is performed in advance so as to reduce the amount of material around the center hole Wb in advance so that the material flow to the inner peripheral surface of the cylindrical portion Wa is anticipated and the amount of flow is not excessive. The shape of a predetermined range VA of W in the axial direction of the center hole Wb is adjusted.

In order to obtain the above-described effects, a load VA is applied to the workpiece by the first die and the second die in a range VA formed so that the diameter of the center hole Wb of the workpiece W is increased from D0 to D5. Thus, the stress ML (FIG. 3) that causes plastic deformation in the workpiece W is set in a range. Here, the range in which the stress ML sufficient to cause plastic deformation in the workpiece W is expanded from the end Wc side facing the upper mold 12 to the deep portion, but the stress tends to decrease as the depth increases. Yes (symbol MS in FIG. 3). For this reason, the flow amount of the material also tends to decrease as the depth of the workpiece W increases. Further, with the progress of the swing forging process, the amount of flow of the material tends to decrease as the plastic deformation of the workpiece W progresses. Therefore, the shape of the range (VA) in which the stress ML sufficient to cause plastic deformation of the work W before the rocking forging process is increased toward the end side Wc facing the upper die 12 so as to increase in diameter. To form. And as it goes to the end Wc facing the upper mold 12, the amount of material in the peripheral part of the center hole Wb is further reduced, and the inner peripheral surface of the cylindrical part Wa regardless of the progress of the swing forging process. The workpiece W is adjusted in advance so that the material flow to the substrate does not become excessive.

Further, in the swing forging forming according to the embodiment of the present invention, the upper die 12 and the lower die 14 approach each other depending on what is important (target) such as dimensional accuracy and machining efficiency in the machining process. The pattern is different. Therefore, by determining the shape of the predetermined range in the axial direction of the center hole Wb of the workpiece W according to the approach movement pattern of the upper mold 12 and the lower mold 14, the approach movement pattern of the upper mold 12 and the lower mold 14 is determined. In this regard, the amount of the material flow F (see FIG. 5B) to the inner peripheral surface of the cylindrical portion Wb is prevented from becoming excessive. By the way, the stress generated in the work W increases as the approaching speed (die feeding speed) of the upper die 12 and the lower die 14 increases, and the range extends to the deep part. For this reason, the shape of each part in the predetermined range in the axial direction of the center hole Wb of the workpiece W is determined in consideration of the die feed speed and the progress of the swing forging process.

For example, by adjusting the approach movement pattern of the upper mold 12 and the lower mold 14 so that the load applied to the workpiece W by the upper mold 12 and the lower mold 14 is constant, the mold feeding speed can be adjusted by swing forging. The initial stage is fast and the final stage is slow. For this reason, the state of stress that causes plastic deformation changes with the progress of swing forging, and the aspect of the material flow to the inner peripheral surface of the cylindrical portion of the workpiece W becomes complicated. Even in such a case, in order to reduce the amount of material around the center hole Wb in advance so that a complicated material flow mode is anticipated in advance and the flow amount does not become excessive, the swing forging process is performed. The shape of a predetermined range VA in the axial direction of the center hole Wb of the workpiece W is adjusted (FIG. 4: S100 to S140).

As another example of the approaching operation pattern of the upper die 12 and the lower die 14, the die feed speed at the beginning of the swing forging is kept constant at a high speed and is maintained near the bottom dead center of the upper die 12, and thereafter the die feed speed. It is also possible to aim to improve the accuracy of the molding surface by making the extremely low speed. Even in such a case, similarly, a complicated material flow mode is anticipated in advance, so that the amount of flow around the center hole Wb is reduced in advance so that the flow amount is not excessive. This can be handled by adjusting the shape of the predetermined range VA in the axial direction of the center hole Wb of the workpiece W before the forging process.

10: Swing forging device, 12: Upper die, 14: Lower die, D0: Diameter (minimum diameter), D1, D2, D3, D4: Diameter, D5: Diameter (maximum diameter), F: Material flow, W: work, Wa: cylindrical portion, Wb: center hole, Wc: cone portion (the upper die and the opposing end), _{W 0:} test work, VA: axial predetermined range

Claims (6)

The first die having an angle in a conical shape is swung and rotated with reference to a predetermined center point, and a disc-shaped workpiece having a center hole is set on the second die that is opposed to the first die in the axial direction, A swing forging method in which the first mold and the second mold are separated from each other and the work is brought into contact with the first mold to form the work.
The diameter of the workpiece before the rocking forging process in a predetermined range in the axial direction of the center hole increases toward the end facing the first die with the workpiece set in the second die. A rocking forging method characterized by forming so as to. A predetermined range in the axial direction that is formed so as to expand the center hole of the work is only caused to cause plastic deformation in the work by a load applied from the first mold and the second mold to the work. 2. The rocking forging method according to claim 1, wherein a stress is generated. 3. The swing forging method according to claim 1, wherein the shape of the center hole of the workpiece in a predetermined range in the axial direction is determined according to the approach movement patterns of the first die and the second die. The approach movement pattern of the first mold and the second mold is adjusted so that a load applied to the workpiece by the first mold and the second mold is constant. Swing forging method. A workpiece before the swing forging step used in the swing forging method according to claim 1,
A predetermined range in the axial direction of the central hole in the state set in the second mold has a shape that increases in diameter toward the first mold side, and the shape of the central hole is
With respect to the test workpiece obtained by simplifying the shape of the workpiece before the swing forging process, swing forging is performed on the test workpiece under different approach movement patterns of the first die and the second die.
For each approach movement pattern, create a database of shapes after rocking forging of the center hole of the workpiece under test,
Based on the database, the material flow occurring in the workpiece before the rocking forging process is predicted,
A workpiece characterized by being determined based on the prediction of the material flow. A method for determining the shape of a workpiece before the swing forging process used in the swing forging method according to claim 1,
A test work that has simplified the shape of the work before the rocking forging process is set in the second die,
The shape after rocking forging of the center hole of the test work for each approach movement pattern is performed for rocking forging under the different work movement patterns of the first mold and the second mold. Database
Based on the database, the material flow occurring in the workpiece before the rocking forging process is predicted,
Based on the prediction of the material flow, the workpiece before the rocking forging step is determined in a predetermined range in the axial direction of the center hole, the shape of which expands toward the first die side. Shape determination method.