JPS6224114Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention allows dust to flow from the outside to the inside of the brake drum through the abutment area between the open end of the brake drum and the outer peripheral edge of the back plate that closes the opening end of the brake drum. This relates to a drum brake dust shield that prevents dust from entering.

[Prior Art] As shown in FIG. 1, a drum brake obtains braking force by frictionally engaging a pair of brake shoes with the inner circumferential surface 45 of a brake drum 41 that rotates together with the wheels. , the back plate 2 covering the open end of the brake drum 41 has a hole 4 in the center through which the axle passes.
4 is provided, and the part surrounding the hole 44 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, and a pair of brake shoes are supported between them.

In this way, the back plate guides and supports the brake shoe, receives the braking torque of the brake shoe, and further serves to close the brake drum. In order to prevent dust from entering the inside of the brake drum, a dust shield is provided at the outer peripheral edge of the back plate. In contrast to the back plate, which has sufficient thickness to withstand braking torque, the dust shield is formed by forming an annular plate thinner than the back plate into an L-shaped cross section, and attaching it to the cylindrical portion 4.
The plates having the numbers 2 and 43 are concentrically connected to each other by welding, and then overlapped with the outer peripheral edge of the back plate and connected by welding.

[Problems to be Solved by the Invention] As described above, in the conventional dust shield, two annular plates must be separately 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.

In view of these problems, the purpose of the present invention is to provide a dust shield for a drum brake that has high material usage efficiency and can reduce the number of processing steps.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention is such that the first cylindrical portion is drawn along the inner side of the first cylindrical portion by drawing the outer peripheral side plate surface of the annular plate. A drawing process is applied to the plate surface to form a second cylindrical part in which the inner and outer circumferential surfaces of the protrusion having an inverted U-shaped cross section are brought into close contact with each other. It is equipped with plate surfaces to be joined.

[Operation] Since the first cylindrical part and the second cylindrical part are integrally press-formed into one annular plate, the use of material (plate) is reduced compared to the case where they are press-formed separately as in the past. efficiency is improved and costs can be reduced.

[Embodiment of the invention] As shown in FIGS. 2 and 3, the back plate 2 is formed from a circular plate, and has a flat mounting surface 3 surrounding the axle hole 4 and a flat mounting surface 3 for supporting the anchor member 35. It has a flat support surface 6 which is approximately oval in shape. The outside of the mounting surface 3 that surrounds the axle hole 4 is provided with a flat surface 12 that is higher than the mounting surface 3 and connected in an annular manner through an inclined surface 5, and a flat surface that has a hole 11 in the upper part of the flat surface 12. 34 is provided, into which a hydraulic cylinder device is fitted and fixed by a bolt inserted into the bolt hole 14.

A support surface 6 that is raised higher than the flat surface 12 is formed in the lower part of the back plate 2 via the inclined surface 5a, and this lower part is connected to the flat surface 12 via the inclined surface 7.

Two rivet holes 38 are provided in the support surface 6, and the rivets 31 inserted through these holes allow the anchor plate 32 for engaging the end of the web of the brake shoe onto the support surface 6 and the web to be released. A retainer 33 that prevents this from occurring is superimposed and fixed. Further, a hole 16 is provided in the local inclined surface 5b adjacent to the inclined surface 5, through which a remote control wire for actuating a known parking brake lever is guided into the interior of the brake drum.

The left and right pair of brake shoes have their ends engaged between a known hydraulic cylinder device and an anchor member 35, and the center portion of the web is fitted with a pin and supported by a hole 15 provided in the back plate 2. It is lightly supported by the back plate 2 via a spring (not shown), and one side edge of the rim of the brake shoe slides onto three flat ledges 13 that are slightly raised from the flat surface 12. Possibly supported.

The dust shield 20 according to the present invention is connected to the outer peripheral edge of the back plate 2, and two inner and outer cylindrical parts 8 and 9 are integrally formed from one annular plate.
That is, the outer circumferential plate surface of the annular plate is drawn to form the cylindrical portion 9, while the inner circumferential plate surface is drawn to raise protrusions in the shape of an inverted U-shape perpendicular to the plate surface. The cylindrical part 8 is formed by
The inner peripheral side plate surface is overlapped with the outer peripheral side plate surface of the back plate 2, and the two are joined by spot welding or the like.

As shown in FIG. 3, the dust shield 20 according to the present invention has a cylindrical portion 8 protruding into the annular groove 46 provided at the open end of the brake drum 41, and is designed to cover the outer periphery of the end of the brake drum 41. The cylindrical parts 9 are combined to form a labyrinth-like shield.

The back plate 2 having the cylindrical portions 8 and 9 described above is press-molded, for example, in a process as shown in FIG.
In step a, an annular recess 61 is press-formed along the peripheral edge on the lower surface of the disk 21, which is the raw material, and in step b, this recess 61 is deeply squeezed to form a groove 6 with an inverted V-shaped cross section.
Set it to 2. Further, in step c, a protrusion having an inverted U-shaped cross section having circumferential surfaces 8a and 8b perpendicular to the plate surface is formed from the groove 62, and in step d, circumferential surfaces 8a and 8b are formed.
are overlapped and brought into close contact with each other, and the disc 2
The cylindrical portion 9 is formed by drawing the peripheral edge of the plate 1 perpendicularly to the plate surface. Then, in step e, a hole 63 is punched in the center to complete the process.

In step c, the cylindrical portion 8 can be molded using a mold as shown in FIGS. That is,
The lower mold 50 has an inner peripheral surface 52, an outer peripheral surface 57, and a bottom surface 5.
1 is formed, and this bottom surface 51
A sliding die 53 divided into four parts in the circumferential direction is supported so as to be movable in the radial direction along the circumferential direction. A wedge mold 55 is interposed between an inclined surface 54 formed on the outer edge of the sliding mold 53 and an outer peripheral surface 57.

In step c, the back plate 2 formed in step b is turned over and placed on the lower mold 50 and the sliding mold 53, and the unfinished cylindrical portion 8 is sandwiched between the inner side surface 52 and the sliding mold 53, Press with the upper die 56. Next, by pushing down the wedge mold 55 and moving the movable mold 53 toward the center of the lower mold 50 (in the direction of the arrow x in FIG. 6), the circumferential surfaces 8a and 8b
are brought into close contact to form the required cylindrical portion 8. At this time, as shown in FIG. 6, the outer diameter of the peripheral surface 8b is contracted, so that the sliding mold 53
Although a radially outward protruding portion 8c is formed in the gap, this does not pose a practical problem.

Inner and outer circumferential surfaces 8a and 8b of the protrusions forming the cylindrical portion 8
The reason why the cylindrical parts 8 and 8 are brought into close contact with each other is that the thickness of the cylindrical part 8 must be reduced in order to insert the cylindrical part 8 into an annular groove (see FIG. 1) provided at the open end of the brake drum.

Note that the sliding mold 53 has a cylindrical shape divided into four parts,
In addition, the outer peripheral surface may be provided with a tapered surface instead of the inclined surface 54, and the wedge shape 55 may also be cylindrical, with a tapered surface formed on the inner peripheral surface.

[Effects of the invention] As mentioned above, the present invention has two parts inside and outside from one board.
Compared to conventional dust shields, the dust shield is made of two cylindrical parts that are integrally molded, which greatly improves the utilization efficiency of the plate materials used, and also reduces welding man-hours, helping to reduce costs.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing an outline of a drum brake equipped with a conventional dust shield, Fig. 2 is a front view of a back plate of a drum brake equipped with a dust shield according to the present invention, and Fig. 3 is a line taken along the lines shown in Fig. 2. 4 is a side sectional view showing the press molding process of the dust shield according to the present invention, FIG. 5 is a side sectional view of the mold used for the press molding, and FIG. 6 is the line shown in FIG. FIG. 3 is a bottom sectional view showing the state after completion of molding. 2... Back plate, 8, 9... Cylindrical portion, 20... Dust shield, 41... Brake drum.

Claims (1)

[Scope of utility model registration request] A first cylindrical part is formed by drawing the outer circumferential plate surface of the annular plate, and a drawing process is applied to the plate surface along the inside of the first cylindrical part so that the inner and outer circumferential surfaces of the protrusion having an inverted U-shaped cross section are brought into close contact with each other. forming second cylindrical portions respectively, and forming second cylindrical portions.
A dust shield for a drum brake, characterized in that the inside of the cylindrical part is provided with a plate surface that overlaps and is joined to the peripheral edge of a back plate.