JPH073252B2 - Clutch drum manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a clutch drum in a centrifugal clutch for a small engine mainly used in working machines such as a brush cutter and a chain saw.

[0002]

2. Description of the Related Art Conventionally, this type of clutch drum has
As shown in the figure, an engaging hole 17 is provided at the center of the side plate 15 of the clutch drum 11 formed by press-molding a steel plate, and the transmission shaft 2
The shaft portion 37 formed at the other end of the driven body 23 having the square hole 21 that engages with the square shaft 31 formed at the end of 9 is provided with the engagement hole 17
And the driven body 23 and the side plate 15 are bonded by copper brazing.

Further, an inner diameter hole 33 in the axial direction is provided in the driven body 23 for broaching the square hole 21 of the driven body 23, and a bearing 27 for axially supporting the outer periphery of the driven body 23.
In order to prevent the grease of FIG. 2 from entering the clutch drum 11 through the square hole 21 and the inner diameter hole 33, the inner diameter hole 33
The plug 35 was inserted into the inside, and the plug 35 and the driven body 23 were bonded and closed by copper brazing.

In FIG. 8, the same reference numerals as those shown in FIGS. 1 to 4 represent the same components.

[0005]

In the above-mentioned conventional clutch drum, the side plate 15 and the driven body 23 are brazed with copper in an oxygen-free state in a high temperature furnace. When copper brazing is applied after heat treatment, the square holes 21 lose their durability, so they are heat treated after copper brazing for polishing finish.
It took a lot of work and the production cost was high.

[0006]

According to the present invention, an engaging hole having a notch is formed at the center of a side plate of a clutch drum formed by press-molding a metal plate, and is formed at the end of a metal driven body. The shaft part is engaged with this engaging hole, the end face of the shaft part is pressed by press molding, deformed and pushed outward, and the side plate is sandwiched between the step part provided on the end face of the shaft part. The side plate is provided so as to enter the notch and to be locked in the rotating direction.

[0007]

When the rotational speed of the engine increases, the shoe of the centrifugal clutch contacts the inner diameter surface of the clutch drum, the clutch drum starts to rotate, and the driven body rotates. The clutch drum is formed by pressing a metal plate.
After engaging the shaft portion at the end of the driven body with the engaging hole provided in the center of the side plate of the clutch drum, press the end surface of the shaft portion by press molding to deform it and push it outward. The side plate is sandwiched between the side plate and the step provided on the outer periphery of the shaft portion, and the side plate is inserted into the notch formed on the outer periphery of the engagement hole to lock the rotation between the shaft portion and the side plate.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In FIGS. 1 to 4, two clutch shoes 7 of a centrifugal clutch 5 are provided on one side surface of a fan 3 fixed to a crankshaft 1 of an engine so as to be swingably opposed by a shaft 9 and attract each other. The inner surface of the circumferential portion 13 of the clutch drum 11 is brought into contact with the thus-provided ammunition (not shown) by centrifugal force. An engagement hole 17 is provided at the center of the side plate 15 of the clutch drum 11, and a plurality of cutouts 19 are provided on the circumference of the engagement hole 17.

An end portion of a cylindrical driven body 23 having a square hole 21 therein is fixed to the engagement hole 17, as described later. The driven body 23 is pivotally supported by the clutch housing 25 by a bearing 27, and the angular hole 31 is engaged with the angular shaft 31 at one end of the transmission shaft 29. In order to perform efficient broaching, the square hole 21 of the driven body 23 is penetrated by an inner diameter hole 33 in the axial direction. Through the inner diameter hole 33, the grease of the bearing 27 enters the clutch drum 11. Inner diameter hole 33 to prevent the clutch from malfunctioning.
A cylindrical plug 35 is inserted therein, and is fixed and sealed.

The clutch drum 11 is manufactured as follows. That is, as shown in FIG. 4, the cylindrical shaft portion 37 formed at the end of the driven body 23 made of steel which has been previously processed and heat-treated has the clutch drum 11 formed by press-molding a steel plate.
The shaft portion 3 is fitted in the engaging hole 17 of the side plate 15 and is in contact with the flange-shaped step portion 39 provided on the outer periphery of the shaft portion 37.
The tip of 7 is formed in advance so as to project from the side plate 15 by a predetermined dimension. The columnar plug body 35 is previously inserted into the inner diameter hole 33 in the shaft portion 37 and is locked to the step portion 41 in the inner diameter hole 33.

When the driven body 23 is placed on the die 43 fixed to the table (not shown) of the press by the lower surface of the step 39 and the tip surface of the shaft 37 is pressed by the punch 45, the die 43 is pressed. The voltage applied to the punch 45 causes a current to flow through the shaft portion 37 to be heated and softened, the end surface of the shaft portion 37 is pressed and deformed, and is extruded outward, and between the step portion 39 and The side plate 15 is sandwiched and the cutout portion 19 is formed.
When it enters the inside and locks the side plate 15 in the rotating direction, and is pushed out inward at the same time, the stopper 35 is sandwiched between it and the step portion 41, and the state shown in FIG. 2 is obtained.

When the rotation of the crankshaft 1 of the engine becomes large, the clutch shoe 7 swings against an ammunition (not shown) to come into contact with the inner surface of the clutch drum 11 to rotate, and the driven body 23 which is integral with the clutch drum 7 is rotated. The power is transmitted to the transmission shaft 29 that engages with.

As shown in FIG. 5, if the commercially available steel ball is used as the plug body 35, the cost will be low and it will be easily available.

The driven body 23 of the present invention may be formed in the shape of a gear (FIG. 6) or a sprocket (FIG. 7), and the shaft portion 37 has a hollow cylindrical shape (FIG. 6) or an inner diameter hole. It may be formed in a columnar shape (FIG. 7) without.

[0015]

The present invention has the following effects. (1) Eliminating troublesome steps such as brazing and welding of steel, it can be efficiently manufactured at low cost by press molding. (2) When the driven body is provided with the inner diameter hole, the plug body for closing the inner diameter hole can be fixed at the same time. (3) When the driven body is preheated, only the shaft is heated by the current to soften and melt, and it can be pressed and fixed without cracks, and the square hole part is tempered. Never. (4) By pressing and intruding a part of the shaft portion into the cutout portion, the rotational movement of the side plate and the driven body can be locked simply, structurally, easily and reliably. (5) No special equipment is required and the existing spot welder can be used, so the equipment is easy and inexpensive.

[Brief description of drawings]

FIG. 1 is a side sectional view of an engine near a centrifugal clutch equipped with a clutch drum according to the present invention.

FIG. 2 is an enlarged side sectional view of a main part.

3 is a front sectional view taken along the line III-III in FIG.

FIG. 4 is a process drawing of press molding before pressing a driven body.

FIG. 5 is a side sectional view of another embodiment of the stopper.

FIG. 6 is a second embodiment in which a driven body is a gear.

FIG. 7 is a third embodiment in which the driven body is a sprocket.

FIG. 8 is a side sectional view of an engine near a centrifugal clutch provided with a conventional clutch drum.

[Explanation of symbols]

 11 Clutch Drum 15 Side Plate 17 Engagement Hole 19 Notch 23 Driven Object 33 Inner Diameter Hole 35 Plug 37 Shaft 39 Step 41 Step

Claims (3)

[Claims] 1. An engaging hole 17 having a notch 19 formed on the outer periphery is provided at the center of a side plate 15 of a clutch drum 11 formed by press-molding a metal plate, and is formed at an end of a driven body 23 made of metal. The shaft portion 37 is engaged with the engagement hole 17, and the shaft portion 3
The end face of 7 is pressed and deformed by press molding and pushed outward, and the side plate 15 is sandwiched between the end plate 7 and the step 39 provided on the outer peripheral surface of the shaft portion 37, and the end plate 7 enters the notch 19. A method for manufacturing a clutch, characterized in that the side plate 15 is provided so as to be locked in the rotating direction. 2. The clutch drum according to claim 1, wherein when the end surface of the shaft portion 37 is pressed and deformed, an electric current is passed through the shaft portion 37 to heat the shaft portion 37 by electric resistance to soften or melt the shaft portion 37. Manufacturing method. 3. The shaft portion 37 is formed in a cylindrical shape, and the end surface of the shaft portion 37 is pushed outward and at the same time, the end portion of the shaft portion 37 and the step portion 41 provided in the inner diameter hole 33 of the shaft portion 37 are formed. The clutch drum manufacturing method according to claim 1 or 2, wherein a plug body 35 for closing the inner diameter hole 33 is sandwiched and provided therebetween.