JPH0147264B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method and apparatus for roll forming a ring having irregularities in the axial direction, such as an automobile wheel rim.

[Prior Art] In order to manufacture a circular ring having unevenness in the axial direction, such as an automobile wheel rim, a belt-shaped flat plate material is wound into a circular ring shape, and the abutting portions are welded and joined to form a ring. An outer roll is pressed onto the ring from the outer periphery to form irregularities while rotating the ring. Fig. 1 shows a part of the ring 1 under processing, where 2 is the processed area of the indentation made by the outer roll, and 3 is the processed area when the direction of rotation of the ring 1 is in the direction of arrow A. It becomes an area. By the way, since the width of the elementary ring 1 is reduced in the processing area 2, a tensile force shown by arrow B acts on the reduced portion. Therefore, the tensile force causes a decrease in wall thickness at the bending corner near the processed portion 2, that is, a decrease in wall thickness.

In order to prevent this thinning, as shown in Figure 2, compressive force (indicated by arrow C) in the direction parallel to the axis of the ring element 1 is applied to the processing area 2 of the element ring 1 to offset the tensile force. However, it is effective to press and shape the outer roll under axial compressive stress. This molding under compressive force was previously proposed by the applicant of the present patent (Japanese Patent Application No. 15907/1982).

[Problems to be Solved by the Invention] However, in the previously proposed method for forming an annular ring, as shown in FIG. Since the integrated outer roll 3 was simply pushed in the radial direction of the ring element 1 while applying an axial force, there was a problem in that the drop portion 1a and the flange portion 1b of the element ring 1 were likely to be sunk.

In order to solve this problem, the cause of the occurrence of spot recesses in the ring during molding was investigated and was as follows.
First, with regard to the pitting that occurs in the drop portion 1a, since the forming of the drop portion 1a is a process to reduce the diameter of the ring 1, the drop portion 1a
Since the inner roll 4 receives a compressive force in the circumferential direction and also receives a compressive force in the axial direction by the inner roll 4, it is inevitably in a state where spot digging is likely to occur.

In such a state, when the rotational force of the ring 1 rotating together with the inner roll 4 is small, when the outer roll 3 is pushed in, it becomes a resistance to rotation, and between the ring 1 and the outer roll 3 and the ring 1 A slip occurs between the inner roll 4 and the inner roll 4. For this reason, the elementary ring 1 is locally subjected to large processing, making it difficult to form a perfectly circular ring.

Furthermore, if the pushing amount of the outer roll 3 per rotation of the inner roll 4 is too large, the resistance to the rotational force of the ring 1 becomes large, causing slippage or decreasing the motor rotation speed. For this reason, the circumference of the elemental ring is locally subjected to large processing, resulting in unevenness. Once such unevenness is formed, it is impossible to correct it in subsequent roll forming, and the product drop portion 1a after forming becomes uneven.

Further, when molding is performed while applying an axial force, a compressive force is also applied in the axial direction in addition to the stress in the circumferential direction. For this reason, spot digging is more likely to occur in the drop portion. Furthermore, in conventional molding, the corners of the drop part were reduced in thickness, which was advantageous for counter-sinking as the drop part flowed to the corner part. If molding is carried out in this state, thinning is prevented, so the above-mentioned flow of the meat cannot be expected, and it is thought that spot digging is likely to occur at any time.

Further, regarding the spot burrs that occur in the flange portion 1b, spot burrs do not occur when no axial force is applied, but spot burrs are likely to appear in the flange portions in the roll forming method in which axial force is applied.

The purpose of the present invention is to prevent the occurrence of spot pits in circular roll forming, which is performed by applying compressive force in the axial direction to prevent wall thinning. It is an object of the present invention to provide a method for forming an annular ring and an apparatus therefor that can address the cause.

[Means for Solving the Problems] In order to achieve this object, in the ring forming method of the present invention, compressive force in the axial direction is applied to the ring, and in this state, the ring is divided into a plurality of pieces in the axial direction. The outer rolls, which are movable relative to each other in the radial direction, are pressed against the ring from the outer peripheral side to form a recess, and the ring is rotated to form a ring.

Further, the ring forming apparatus of the present invention for carrying out this ring forming method includes a pair of inner rolls that apply compressive force in the axial direction to the ring, and an upper part of the middle part of the pair of inner rolls. It consists of an outer roll provided. The outer roll is divided into a plurality of rolls in the axial direction, for example, in the axial direction of the outer roll,
It has a three-part configuration consisting of a drop part forming roll that forms the drop part of the element ring and flange part forming rolls provided on both sides of the drop part forming roll, and these three rolls are configured to be able to be displaced in the radial direction relative to each other. ing. An inner roll is provided on the inner circumferential side of the element ring, and the inner roll is divided in the axial direction like the outer roll and is configured to be able to be displaced relative to each other following the outer roll. .

[Function] In the ring forming method and device as described above, the inner and outer rolls are divided in the axial direction and the gap between the inner and outer rolls is properly maintained, thereby forcibly preventing spotting. At this time, it is desirable that the gap be equal to the plate thickness of the ring, or slightly larger than the plate thickness to prevent spotting. However, from the point of view of increasing the rotational force of the ring to help prevent spotting, it is better to make the gap equal to the plate thickness. Thereby, it is possible to cope with the pitting of the drop portion and the flange portion due to the circumferential compressive force and the axial compressive force as explained in the cause of the occurrence of spot pitting.

In addition, in order to prevent slips and increase the rotational force of the ring, flaring and curved rim section forming are performed on the same roll forming machine.In other words, flaring is performed first to reduce the rotational force transmitted to the ring by the inner roll. If it is made large and then formed using inner and outer rolls, it is effective in preventing the ring from slipping. This is easily achieved by making the inner and outer rolls split. As a result, it is possible to deal with the spotting caused by slipping when the rotational force of the ring is small, as explained in the cause of spotting.

Furthermore, as a countermeasure to counter the occurrence of spot pitting, which is caused by the roll rotation speed decreasing due to the rotational resistance when pushing the outer roll and the amount of push of the outer roll per rotation of the inner roll becoming excessive, as explained in the cause of spot pitting, This can be dealt with by controlling the roll rotation speed to achieve an ideal condition, for example a constant rotation speed, which can be easily achieved with split rolls. Thus, the said objective is achieved by split roll forming.

[Embodiments] Hereinafter, preferred embodiments of an apparatus for carrying out the method for manufacturing a ring according to the present invention will be described with reference to the drawings.
In addition, in the following explanation, the case where the outer roll is above the inner roll and the outer roll is rolled down with respect to the inner roll to form a ring is explained, but the positional relationship between the outer roll and the inner roll is is not limited to the top and bottom.

FIGS. 4 and 5 show a split outer roll according to an embodiment of the present invention. As shown in FIG. 4, the outer roll 10 is divided into three rolls in the axial direction. The center roll is a drop part forming roll 11 for forming the drop part of the ring, and the rolls on both sides are flange part forming rolls 12 and 13 for forming the flange part of the ring.
The drop forming roll 11 can be rolled down relative to the flange forming rolls 12 and 13 in a direction perpendicular to the axial direction.

As an example of the mechanism for lowering the outer roll 10, the fourth
Fig. 5 shows a lowering mechanism using an eccentric shaft. The eccentric shaft 14 has an eccentric part 15 and a non-eccentric part 16, and the drop part forming roll has an eccentric part 1.
5, the flange portion forming rolls 12 and 13 are rotatably supported by the non-eccentric portion 16. Eccentric shaft 14
The roller itself does not rotate together with the outer roll 10 during ring forming and is fixed. A tube shaft 17 is integrally joined to the flange forming rolls 12 and 13, and rotates integrally with the flange forming rolls 12 and 13. 18, 19, and 20 are bearings for rotation, respectively. The tube shaft 17 is forcibly rotated by the rotation drive means, whereby the flange portion forming rolls 12 and 13 are rotated together with the tube shaft 17.
On the other hand, when the drop forming roll 11 is pressed against the rotating ring 21 during forming, it can freely rotate due to the frictional force generated at that time. Drop part forming roll 1
1. The flange forming rolls 12 and 13 are moved up and down as a whole by a cylinder 22 shown in FIG. Further, the vertical movement of the drop part forming roll 11 with respect to the flange part forming rolls 12 and 13 is performed by rotating the eccentric shaft 14 by a certain angle, that is, as shown in FIG. For example, the center D of the eccentric portion 15 moves to point D',
The drop forming roll 11 moves from rotation at the position 11' to rotation at the position shown at 11''. During rolling using such an eccentric shaft 14, the center D of the drop forming roll 11 rotates while drawing a circular arc. Since it is rolled down, it is not rolled down vertically in a straight line.

6 to 8 show other examples of independent rolling down mechanisms for the outer roll 10. In the figure, 23 is a drop part forming roll 11, a flange part forming roll 1
2 and 13 are cylinders that move up and down as a whole, and 24 is a cylinder that moves the drop part forming roll 11 up and down relative to the flange part forming rolls 12 and 13. Drop part forming roll 1
1, the drop forming roll 11
To prevent it from escaping laterally, it is pressed by a back up 25 and a bearing 26 as shown in FIG. 7, or by a pair of back up rolls 27 as shown in FIG. In such an independent rolling down mechanism, the drop forming roll 11 can be rolled down vertically and linearly.

FIG. 9 shows the entire ring forming apparatus. In the figure, the outer roll 10 is supported by a frame 28 and is moved up and down by a cylinder 22. A cylinder 29 is connected to the eccentric shaft 14 and rotates the eccentric shaft 14. Therefore, by operating the cylinder 29, the drop part forming roll 11 is rolled down independently with respect to the flange part forming rolls 12 and 13.

On the other hand, on both sides of the ring element 21 in the axial direction, inner rolls 30 and 31, which serve as a pair of pressurizing means for holding the element ring 21, are provided so as to be able to move forward and backward while facing each other. The outer roll 10 is located above the intermediate portion of the inner rolls 30 and 31. At least one of the inner rolls 30 and 31 (in the illustrated example, one inner roll 30
A motor 32 is connected to the inner roll 30 and forcibly drives the inner roll 30 to rotate around its axis. motor 32
The inner roll 30 is supported by a movable base 50, and the movable base 50 is capable of reciprocating in the axial direction by a cylinder 33 connected to the movable base 50.

Further, the table 34 on which the motor 32 and the cylinder 33 are placed has two vertical cylinders 35 and 36.
By operating the cylinders 35 and 36, the axial angle α of the inner roll 30 from the horizontal line can be arbitrarily set. By providing the two cylinders 35 and 36 in this way and adjusting the angle α, the cylinder 3
3 to move the inner roll 30 forward and backward relative to the ring 21, the height of the operating point E can be adjusted to a constant level.

Further, the two vertical cylinders 35 and 36 are fixed on a common movable base 37, and the movable base 37 is rotatable in a horizontal plane about a support shaft 38. The movable base 37 is rotated in a horizontal plane by being connected to the cylinder 39. As a result, the pressurized portion of the ring 21 of the inner roll 30 is transferred to the ring 21.
1 in the circumferential direction, and the distribution of the compressive force C in FIG. 2 can be changed.

On the other hand, as shown in FIG. 10, the inner rolls 30 and 31 have a flared part at a position corresponding to the flange part of the ring element 21 when the ring element 21 is held between them. The diameter of the flange is expanded and the flange is pressed against the flange to prevent slippage. The tips of the inner rolls 30, 31 are rounded off, and an elastic material 42 such as urethane rubber is attached to the corners in the circumferential direction. Due to this inner roll structure, the inner rolls 30, 31 are substantially composed of flange part forming rolls 43, 44 capable of performing flaring processing, and a drop part forming roll 45 intermediate therebetween. And inner roll 30,3
As shown in FIG. 10, the drop forming roll 45 on the first side is made of an elastic material 42 on its outer periphery. The surface can move relative to the flange forming rolls 43 and 44. Accordingly, the inner rolls 30 and 31 are also rolls that can be substantially divided into three parts in the axial direction. Note that the three-part roll on the inner rolls 30 and 31 side may be a roll that is completely separated into three parts similarly to the outer roll 10. In addition, the outer roll 10
The gap between the drop part forming roll 11 and the flange part forming rolls 12 and 13 is adjusted to the thickness of the ring 21. Note that when the elastic material 42 is used for the drop forming portions of the inner rolls 30 and 31, the gap adjustment is automatically performed by deforming the elastic material 42.

Note that in the above device, the inner rolls 30, 3
Although the axial movement of 1 is carried out by the cylinder 33, as shown in FIG.
A cylinder 47 may be connected to the movable base 46, and the cylinder 47 may move the movable base 46 in the axial direction.

Next, an embodiment of the ring manufacturing method of the present invention will be described, taking as an example a case in which it is carried out using the apparatus of the embodiment.

First, the elementary ring 21 is prepared. The element ring 21 is usually formed by bending a flat metal plate into an annular shape and welding the abutted portions together. The raw ring 21 is held between a pair of inner rolls 30 and 31, which are pressurizing means. In this case, the axial directions of the inner rolls 30, 31 are on the horizontal line as shown in FIG. When the inner rolls 30 and 31 are pressurized in a direction toward each other, the diameter of both sides of the ring 21 is expanded by the flared portions 40 and 41. This flaring allows the ring 21 to come into close contact with the inner rolls 30, 31, thereby preventing slippage during rotation. Subsequently, the inner rolls 30 and 31 are moved to the cylinder 3.
5 and 36, the axes thereof are tilted and a large compressive force is applied to the upper part of the element ring 21. At this time, the cylinder 39 is actuated to tilt the inner rolls 30 and 31 into the horizontal plane, thereby slightly shifting the compressive force region to the front side in the direction of rotation of the ring element in the processing section, thereby facilitating the subsequent forming.

Subsequently, the outer roll 10 is rolled down. At this time, since the center of the drop forming roll 11 is at the position D in FIG. 5, the ring 21 is first pressed at both ends by the flange forming rolls 12 and 13. The flange forming rolls 12 and 13 of the outer roll 10 are forcibly rotated, but the rotational speed is controlled so that the circumferential speed is the same as that of the flange forming rolls 43 and 44 of the inner rolls 30 and 31, so that no force is applied to the flange. It is ensured that no heavy loads are applied. Next cylinder 2
9 to rotate the eccentric shaft 14, and the eccentric part 1
5 is rotated to roll down the drop forming roll 11 relative to the flange forming rolls 12 and 13. As a result, a drop portion begins to be formed on the element ring 21. Since the drop portion forming roll 11 rotates as the ring 21 rotates as the inner rolls 30 and 31 rotate, the drop portion forming roll 11 is pressed against the ring 21 and rotates. By gradually rotating the eccentric shaft 14, the element ring 2 is
Deepen the molding of the drop part in step 1. At this time, the drop portion forming rolls of the inner rolls 30 and 31 are deformed by the deformation of the elastic member 42 while automatically maintaining the gap between the drop portion forming rolls 11 of the outer roll 10 at the original ring plate thickness. Therefore, in this molding, the raw ring 21 is molded while adjusting the gap between the inner and outer rolls. Therefore, no pitting can occur during molding. Moreover, since the state in which compressive force is applied to the upper part of the ring 21 due to the inclination of the inner rolls 30 and 31 is maintained, the thickness of the ring 21 does not decrease. In this way, the formation of a ring is achieved.

[Effects of the Invention] Therefore, the following effects can be obtained by using the ring forming method and device of the present invention.

First, since the outer roll is divided in the axial direction and the ring is formed while maintaining a proper gap between the inner and outer rolls, spot digging can be forcibly prevented. In other words, when forming while applying compressive force in the axial direction to cancel out the tensile force generated when processing the drop part, the axial compressive force and the compressive force in the circumferential direction due to the diameter reduction of the drop part inevitably cause a counter-sink. Since the gap between the inner and outer rolls of both the drop part and the flange part is adjusted during molding, the occurrence of spot pitting can be prevented.

In addition, the inner and outer rolls are substantially divided in the axial direction, and the ring can be rotated by holding the flange portion of the ring between the inner and outer rolls. This prevents slips between the ring and the inner and outer rolls, and prevents the ring from slipping. The occurrence of digging is prevented.

In addition, since the flange portion of the ring is held between the inner and outer rolls and the slip ring is rotated, by keeping the number of rotations of the rolls constant, the number of rotations of the ring will also be constant, and per rotation of the inner roll. The pushing amount of the outer roll is also equalized, and the pushing amount of the drop portion forming roll of the outer roll is prevented from becoming excessive, and occurrence of spot pitting due to an excessive pushing amount of the outer roll is also prevented.

In this way, all the causes of spot pitting are solved, so when the ring manufacturing method and its device of the present invention are used, the conventional problem can be solved while maintaining the already proposed effect of preventing thickness loss during ring forming. It is possible to prevent the occurrence of spot digging.

[Brief explanation of drawings]

Fig. 1 is a plan view of the vicinity of the ring processing section, Fig. 2 is a plan view when an axial compressive force is applied to the ring shown in Fig. 1, and Fig. 3 is a plan view of the annular forming device already proposed. 4 is a sectional view of an outer roll according to the ring manufacturing method and apparatus of the present invention, and FIG.
6 is a sectional view of an outer roll lowering mechanism according to an example different from FIGS. 4 and 5, FIG. 7 is a side view of the outer roll in FIG. 6, and FIG. The figure is a side view of the outer roll of FIG. 6 according to an example different from that of FIG. 7, FIG. 9 is an overall schematic perspective view of the ring forming apparatus according to the present invention, and FIG. Cross-sectional view when the inner roll is inserted into the ring, No. 11
The figure is a cross-sectional view of the state in which the inner roll axis is further tilted from the horizontal line and the outer roll is rolled down to form a drop part from the state shown in FIG.
FIG. 6 is a partial perspective view of a device according to a different example from the one shown in the figure. 10... Outer roll, 11, 45... Drop part forming roll, 12, 13, 43, 44... Flange part forming roll, 14... Eccentric shaft, 15... Eccentric part, 16... Non-eccentric part, 17 ...Tube shaft, 21...
Elementary ring, 22, 23, 24, 29, 33, 35, 3
6, 39, 47...Cylinder, 30, 31...Inner roll, 32...Motor.

Claims (1)

[Claims] 1. A compressive force in the axial direction is applied locally on the circumference by a pair of inner rolls that can move back and forth to the element ring, and in this state,
The outer rolls are divided into a drop part forming roll and a flange part forming roll in the axial direction and are mutually displaceable in the radial direction, while sequentially changing the amount of protrusion of the drop part forming roll with respect to the flange part forming roll,
A circle is formed by rotating the element ring while forming a radial depression locally on the circumference of the element ring by pressing from the outer circumferential side against a pressurizing part of the axial compressive force of the element ring. How to form a ring. 2. A patent claim in which the outer roll is constituted by a three-part roll consisting of one drop part forming roll and a pair of flange part forming rolls on both sides thereof, and the outer roll is pressed against the raw ring to form a circular ring. The method for forming an annular ring according to item 1. 3 A pair of inner rolls that apply compressive force in the axial direction to the raw ring are provided, an outer roll is provided above the middle part of the pair of inner rolls, and the outer roll is divided in the axial direction of the outer roll. A ring forming device characterized in that the rolls are movable in the radial direction relative to each other. 4. The outer roll is constituted by a three-part roll consisting of a drop part forming roll and a flange part forming roll provided on both sides thereof, and the drop part forming roll and the flange part forming roll can move forward and backward with respect to the middle part of the pair of inner rolls. 4. The ring forming apparatus according to claim 3, wherein the annular ring forming apparatus is rotatably supported by an eccentric portion and a non-eccentric portion of an eccentric shaft provided in the eccentric shaft. 5. The outer roll is composed of a three-part roll consisting of a drop forming roll and a flange forming roll provided on both sides thereof, and a cylinder that displaces the drop forming roll in the radial direction displaces the flange forming roll in the radial direction. The ring forming device according to claim 3, which is provided separately from the cylinder.