JPH0316201B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a drum brake in which the brake drum The present invention relates to a method of manufacturing a dust shield that prevents dust from entering the inside of the device.

[Prior Art] As shown in FIG. 1, a drum brake uses an inner circumferential surface 35 of a brake drum 31 that rotates together with the wheels.
Braking force is obtained by frictionally engaging a pair of brake shoes, and the back plate 2 that covers the open end of the brake drum 31 has a hole 3 in the center through which the axle passes.
4 is provided and the part surrounding the hole 34 is fixed to a non-rotating part of the vehicle by bolts. A hydraulic cylinder device and an anchor member are fixed to the inner surface of the back plate 2,
A pair of brake shoes is supported between the two.
Therefore, the back plate 2 serves to guide and support the brake shoe, to receive the braking torque of the brake shoe, and to close the open end of the brake drum.

The dust shield 32, which prevents dust from entering the inside of the brake drum, is made by bending an annular flat plate thinner than the back plate 2, which has sufficient strength against braking torque, into an L-shaped cross section to form a cylindrical portion 32c. It is formed by overlapping concentrically on the outer surface of the back plate 2 and is joined by welding. In the conventional dust shield 32 described above, an annular plate must be punched out from a flat plate, so the effective utilization rate of the material is extremely low and it is disadvantageous in terms of cost.

On the other hand, the method of continuously manufacturing a dust shield from coil material by roll forming can only use coil material as a raw material and cannot use a rectangular plate. Moreover, the rolling equipment and its accompanying equipment become enormous, which is disadvantageous in terms of cost for producing a wide variety of products.

If an annular dust shield with an L-shaped cross section is formed by direct roll forming from a rectangular plate, wrinkles will form on the plate surface perpendicular to the central axis, making it impossible to obtain a satisfactory product. In addition, the spinning (spatula drawing) processing method requires a long processing time per piece.
Production efficiency is poor because welding is required to join the rectangular plates into a cylindrical shape.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the object of the present invention is to provide a dust shield that can efficiently and inexpensively produce a ring-shaped dust shield with an L-shaped cross section from a rectangular plate using simple equipment. An object of the present invention is to provide a method for manufacturing a shield.

[Means for Solving the Problems] In order to achieve the above object, the method of the present invention includes forming both ends of a rectangular plate having a predetermined width and approximately the same length as the outer periphery of the back plate that covers the open end of the brake drum. The rectangular plate is cut diagonally so that one side edge is shorter than the other side edge, and an intermediate formed plate having an L-shaped cross section and having plate surfaces perpendicular to each other is formed from the rectangular plate. The plate surface having the other side edge is rolled so that the rolling reduction ratio of the plate surface having the other side edge is larger than that of the plate surface having the side edge, so that the plate surface is curved into a cylindrical shape and the plate surface is perpendicular and flat with respect to the central axis. A dust shield having an annular shape with an L-shaped cross section is obtained.

[Operation] According to the present invention, rectangular plates are formed into an L-shaped cross section with their plate surfaces orthogonal to each other, and then one of the plate surfaces is rolled at a larger reduction rate than the other, and rolled into an annular shape. Engage it to get the required dust shield.

[Embodiments of the Invention] As shown in FIG. 2, the present invention includes a rectangular plate 3,
The annular dust shield 32 having a desired cross-sectional shape is preferably formed from a steel plate.
First, as shown in FIG. 3, a rectangular plate 3 of a required length is cut diagonally at both ends 4 so that one side edge is shorter than the other side edge.
As shown in FIG. 4, the plate surface 32b and the plate surface 3 are bent by a roll or a bender and are perpendicular to each other.
An intermediate molded plate 3A with an L-shaped cross section having a diameter of 2c is obtained.

Next, as shown in FIG. 5, the intermediate forming plate 3A
is sandwiched between a pair of upper and lower rolls 12 and 13 and rolled. In this case, if the reduction ratio of the plate surface 32c that becomes the cylindrical part of the dust shield is increased (the plate thickness of the plate surface 32c is made thinner and extended in the longitudinal direction),
The straight intermediate forming plate 3A is curved into an annular shape. The rolling reduction rate is controlled by the distance between the drive shaft 5 of the roll 12 and the drive shaft 15 of the roll 13.

The drive shafts 5, 15 of the rolls 12, 13 are arranged parallel to each other. The roll 12 has an end surface 6 that abuts one side edge of the intermediate forming plate 3A, a circumferential surface 7 parallel to the axis 5 corresponding to the plate surface 32c, a conical surface 8 corresponding to the bent portion 32d, and a plate surface. End face 9 corresponding to 32b
It is equipped with Similarly, the roll 13 also includes an end surface 16 corresponding to the plate surface 32b of the intermediate forming plate 3A, a conical surface 17 adjacent thereto, and a circumferential surface 18 parallel to the axis 15.

An intermediate forming plate 3A is formed by a pair of rolls 12 and 13.
In order to form an annular dust shield, an external force is applied to bring the shafts 5 and 15 closer to each other and an external force is applied to press the end surface 16 against the end surface 9, and the circumferential surface 7 and the circumferential surface 18 are rolled into the plate surface 32c. (processing to stretch the board thinly).

By making the rolling reduction applied to the plate surface 32c at the circumferential surfaces 7 and 18 larger than the rolling reduction applied to the plate surface 32b at the end surfaces 9 and 16 (an average value in the width direction of the plate), A straight intermediate forming plate 3A shown in is curved into an annular shape. Pre-formed intermediate plate 3
If both ends 4 of the plate surfaces 32b and 32d of A are cut diagonally, the elongation due to the difference in rolling reduction between the plate surfaces 32b and 32c will be absorbed, and as shown in FIG. Both ends 4 are almost aligned.

In the embodiment shown in FIG.
2 and 23, connect the shaft 25 of the roll 23 to the roll 1.
2 and arranged at an angle to the axis 5 of FIG. The roll 23 has a circumferential surface 27 corresponding to the conical surface 8 of the roll 12.
A groove-shaped one is adopted in which a conical surface 26 facing the end surface 9 on both sides of the circumferential surface 27 and a conical surface 28 facing the circumferential surface 7 are provided.

In this embodiment, when the inclination of the axis 25 of the roll 23 is changed, the plate surface 32b changes
The rolling reduction ratio of c changes.

In the above-mentioned embodiment, the dust shield is provided with the conical surface 32d between the plate surface 32b and the plate surface 32c which are orthogonal to each other. However, as shown in FIG. and board surface 3
Even in the case of a dust shield with an L-shaped cross section where 2c is orthogonal, the dust shield can be formed from a rectangular plate by changing the shape of the roll.

[Effects of the Invention] As described above, the present invention has two ends of a rectangular plate having a predetermined width and approximately the same length as the outer periphery of the back plate that covers the open end of the brake drum. The rectangular plate is cut diagonally so that it is shorter than the edge, and an intermediate molded plate having an L-shaped cross section and having plate surfaces perpendicular to each other is formed from the rectangular plate, and the intermediate molded plate is cut diagonally so that it is shorter than the plate surface having one side edge. Roll rolling so that the reduction ratio of the plate surface having the other side edge is large,
Since the purpose is to obtain an annular dust shield with an L-shaped cross section, which has a cylindrically curved plate surface and a flat plate surface perpendicular to the central axis, the flat plate surface perpendicular to the central axis is made without wrinkles. Can be finished with a smooth surface.

Since rectangular plates are used as raw materials, it is easy and efficient to switch to products with different specifications (short start-up time, etc.) using the same equipment, making it suitable for high-mix, low-volume production.

[Brief explanation of the drawing]

FIG. 1 is a side cross-sectional view showing the relationship between the brake drum and the back plate showing the state in which the dust shield is attached; FIGS. 2 and 3 are perspective views showing the processing process of the plate used in carrying out the method of the present invention; Fig. 4 is a perspective view showing the state of intermediate forming of the plate, Fig. 5 is a front view of a rolling machine for forming an annular dust shield from the intermediate forming plate, and Fig. 6 is a diagram of the dust shield formed by the method of the present invention. FIG. 7 is a front view showing another rolling apparatus, and FIG. 8 is a perspective view of another dust shield formed by the method of the present invention. 2: back plate, 3: plate, 4: end, 12, 13, 2
3: Roll, 31: Brake drum, 32: Dust shield, 32b, 32c: Plate surface.

Claims (1)

[Claims] 1. Cut both ends of a rectangular plate having a predetermined width and approximately the same length as the outer circumference of the back plate that covers the open end of the brake drum so that one side edge is shorter than the other side edge, An intermediate formed plate having an L-shaped cross section and having plate surfaces perpendicular to each other is formed from the rectangular plate, and the rolling reduction ratio of the plate surface having the other side edge is lower than that of the plate surface having the one side edge. A dust shield characterized in that the dust shield is rolled so as to have a large diameter to obtain an annular dust shield having an L-shaped cross section and having a cylindrically curved plate surface and a flat plate surface perpendicular to the central axis. manufacturing method.