JPH0138576B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a clutch drum, and in particular, to a method of forming a clutch drum, in particular, by sheet metal processing, a plurality of groove-shaped teeth are formed on the inner circumferential surface of the drum, forming a pair of teeth and extending in the axial direction. It relates to a method of forming.

For example, in recent years, pulleys, gears, etc. for timing belts have been manufactured thinner and with fewer man-hours than conventional machined products, resulting in lower product costs and lighter products. Establishment of manufacturing technology using sheet metal processing is attracting attention, and in response to this demand, the following method has been proposed as a conventional technique for forming tooth profiles of a predetermined shape on the outer surface of a cylindrical member (Japanese Patent Application Laid-Open No. Showa 54-116376
issue).

FIG. 1 is a sectional view of an apparatus used to implement this prior art technique. Here, a drum-shaped material 2 is set in a die 1 having a trapezoidal concave portion on the circumference, and then the material 3 is lowered to press and support the upper surface of the material with a presser member 4 interlocking with the material 3. At the same time, this is also the slope 6 of the guide member 5 that is linked to the mechanism 3, and the back of the punch 8, which is arranged with its tip facing the trapezoidal recess of the die 1 and can advance and retreat radially under the guidance of the holder 7. The end guide slope 9 is pressed to move it forward. As a result, the tip of the punch 8 pushes a predetermined outer peripheral portion of the material 2 into the trapezoidal recess of the die 1, forming a recess on the entire outer periphery of the material 2. The protrusions formed between these recesses act, for example, as teeth that engage with a timing belt.

However, in this prior art, the tooth profile is formed on the outer periphery of the material 2 by moving the radially arranged punches 8 forward in the horizontal direction using the slope 6 of the guide member 5 as a cam surface. In addition to the problem that the structure of the mold becomes complicated and the cost of the mold increases, there is also the problem that the mold becomes large, especially in the horizontal direction. This would pose significant difficulties in securing such facilities.

In order to solve these problems, attempts have been made to form a disc-shaped blank into a toothed cylindrical shape in a single press process, but this technique involves poor processing, and the product has no teeth. Wrinkles and peeling occur on parts and other parts, the product accuracy is low, and furthermore, the unreasonable force acting on the mold causes early breakage of the mold, which brings about problems other than those mentioned above.

The present invention advantageously solves these problems of the prior art. In particular, the blank material is squeezed into a dish shape, and a convex portion is formed at the location where the pair of teeth are formed, and a recess is formed between the portions where the pair of tooth profiles are formed. , Flange-down processing is performed on this plate-shaped blank material, and a predetermined number of grooves are provided in the convex portion to form tooth profile pairs, and finishing processing is performed to form a rough tooth profile defined by the grooves. To provide a method for forming a clutch drum, which has a simple structure and enables a tooth forming shape to be formed using a small mold, and which can sufficiently prevent wrinkles, peeling, etc. of the product and improve product precision. It is something to do.

The present invention will be explained below based on illustrated examples.

FIG. 2 is an explanatory view showing the molding method according to the present invention in the order of steps, and FIG. 3 is a cross-sectional view comparing and showing the molding state of the portion corresponding to the tooth profile in each step.

The product in the illustrated example is a clutch drum for a clutch, which controls power transmission by engaging the clutch plate with each groove-shaped tooth profile provided on the inner circumferential surface, and the required precision of the tooth profile shape is The shape accuracy is 0.1 or less against the overall gauge, and the plate thickness accuracy is 85 to 90% or more of the material plate thickness.

In the method according to the present invention, first, a disk-shaped blank material 11 as a raw material shown in FIG. 2a is drawn into a dish shape as shown in FIG. 2b by draw forming.
The dish-shaped member 12, which is a draw-molded product shown here with the dish turned upside down, has a side wall 12a, preferably a side wall 12a, and a flange portion 1.
2b, a convex portion 12c and a concave portion 12d are formed at predetermined intervals in the circumferential direction and protrude outward. The convex portion 12c of the side wall 12a, as shown by the dashed line in FIG. have sufficient width and protruding height to

Next, the dish-shaped member 12 as a draw-molded product
is subjected to rough serration processing using a press to narrow down the flange portion 12b, which forms the dish-shaped member 1.
A groove 15 is provided in the center of the above-mentioned convex portion 12c of the flanged side wall 14, and a groove 15 is provided in the center of the above-mentioned convex portion 12c of the flanged side wall 14. As shown, a pair of coarse tooth profiles 16 are formed at predetermined intervals in the circumferential direction and each has a wavy cross-sectional shape. The corrugated surfaces of these pairs of rough tooth profiles 16 have dimensions that intersect each corner of the tooth profile 13 as the final product, as shown by the two-dot chain line in FIG. That is, in this example in which the recesses provided on the inner peripheral surface of the drum act for power transmission, the waveform itself is curved so as to protrude slightly more toward the outer peripheral surface than the tooth profile 13, and the outer surface is , each corner projecting toward the outer peripheral surface of the tooth profile 13 and its inner surface intersect with each corner of the recess on the inner peripheral surface.

Note that the holes 17 in the top wall shown in FIGS. 2b and 2c,
Reference numerals 18 serve as positioning holes when draw molding and rough serration processing are performed using a transfer machine, and these drilling steps are not essential components of the present invention.

Finally, the rough tooth profile 16 provided on the side wall 14 is finished by restrike serration processing using a press, and the tooth profile 13 as the final product is made so that the recesses on the inner circumference side have sufficient accuracy. (see solid lines in Figure 2d and Figure 3).

This restrike serration is generally a process that corrects the tooth profile by introducing compressive strain that counteracts the tensile strain caused by the pre-processing, but preferably ironing is performed at the same time as this process. Machining is also performed, thereby eliminating variations in the thickness of the tooth profile 13, further increasing the precision of the tooth profile, and making the inner surface of the tooth profile 13 smoother. Restrike serration accompanied by this ironing process, for example, connects the clear run of the punch and die by 80 to 90% of the plate thickness at the convex part a and concave part b of the tooth profile 13 shown in Fig. 3. This can be achieved by setting the side wall part c to 75 to 85% of the plate thickness.

In addition, in FIG. 2d, a central opening 19 is provided in the top wall and the lower end of the side wall 14 is cut off due to the purpose of using the clutch drum as a power transmission means, but these steps are also similar. This can be changed or omitted as appropriate depending on the use of the toothed drum, and is not an essential configuration of the present invention.

According to such a forming method, each process of draw forming and rough serration forming makes it easy and reliable to form a tooth profile as a final product, and in particular, the convex portion 12c of the dish-shaped member 12 is easily and reliably formed during the subsequent rough serration process. The side wall 1 facilitates the machining of the rough tooth profile 16, and
4 and their tooth profiles 16 from occurring, such as wrinkles and peeling.

Note that if the flange portion 12b of the dish-shaped member 12 is also provided with a convex portion that is continuous with the convex portion 12c of the side wall 12a, these convex portions will act as if they were wrinkles, or in other words, the positions where gaps in the material occur during rough serration processing. Since it acts as if the formation position of the rough tooth profile 16 is specified in advance, it is possible to prevent the occurrence of wrinkles during flange down, and also to prevent the formation of the rough tooth profile 1.
6 becomes easier to form.

Further, the flange down and the formation of a rough tooth profile in the rough serration processing process not only make it extremely easy to form the tooth profile as a final product, but also function effectively to improve the accuracy of the tooth profile.

Furthermore, when ironing is applied to a rough tooth profile at the same time as the restriking serration process, variations in the thickness of the tooth profile are eliminated and the surface thereof becomes smoother.

The clutch drum as a toothed drum configured in this way is connected to, for example, a planetary gear, and includes a plurality of clutch plates having teeth corresponding to the tooth profile of the clutch drum interposed inside the gear, and a plurality of clutch plates which are also connected to the clutch drum. It is located inside the clutch disk between each clutch plate, and functions to transmit or cut off the driving force of the input shaft to the planetary gear in cooperation with the clutch disk connected to the input shaft. .

The present invention has been described above with reference to the illustrated example, but in the illustrated example, the pair of tooth profiles provided at a predetermined interval in the circumferential direction of the side wall may be replaced by three or more pairs.

Therefore, according to the present invention, each step can be performed only by drawing with a press machine, and the mold can be made small and simple, which reduces the cost of the mold and allows processing using a transfer machine. It becomes extremely easy to attach the mold when performing this process, and it is possible to mass-produce stamped products with stable quality at low cost.

In addition, by single-draw forming a disc-shaped blank into a dish shape with a convex portion on the outer surface of the side wall, it becomes easier to form the tooth profile during rough serration processing, and it also prevents wrinkles, peeling, etc. during forming the tooth profile. This can be advantageously prevented, and the machining accuracy of the tooth profile is also improved. Furthermore, the restrike serration process after the rough serration process makes the structure of the material dense and smooth, increasing tooth profile accuracy and strength, and these things are further improved when the restrike serration process is performed with ironing. do.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the device used in the conventional method;
FIG. 2 is an explanatory view showing the processing method according to the present invention in the order of steps, and FIG. 3 is a cross-sectional view comparing and showing the molding state of the portion corresponding to the tooth profile in each step. DESCRIPTION OF SYMBOLS 11... Blank, 12... Dish-shaped member, 12a... Side wall, 12b... Flange part, 12c... Convex part, 12d
... recess, 13... tooth profile, 14... flange-down side wall, 15... groove, 16... rough tooth profile.

Claims (1)

[Claims] 1. When forming a clutch drum having a plurality of tooth profile pairs located at predetermined intervals on the inner circumferential surface,
The blank material is drawn into a dish shape, and a convex part is formed at the location where the tooth profile pair is formed, and a concave part is formed between the tooth profile pair forming part, and then a flange down process is performed on the blank material that has been drawn into the dish shape. A method for forming a clutch drum, characterized in that a predetermined number of grooves are provided in the convex portion to form pairs of tooth profiles, and then the rough tooth profiles defined by the grooves are subjected to a tooth profile finishing process.