JP2541907B2 - Brake drum rotation transmission shaft retaining structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft mounting hole of a shaft fixing portion integrally fixed to a braking drum such as a clutch drum and a brake drum used in a relatively small prime mover such as a brush cutter and an agricultural machine. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation transmission shaft retaining structure for a braking drum, which prevents the rotation transmission shaft to be mounted from penetrating from the end of a shaft mounting hole into the braking drum.

[0002]

2. Description of the Related Art Generally, a part in which a braking drum and a shaft fixing portion provided on the braking drum coaxially with the drum cylinder are integrated is called a "braking drum cambi". A conventional braking drum cambi is shown in FIGS. 5 and 6. In these drawings, reference numeral 1 denotes a braking drum having a substantially U-shaped side cross section, which is manufactured by press working from a thick sheet metal raw material, and has a peripheral plate portion 2 on the inner peripheral surface of which a braking shoe (not shown) is slidably contacted, In the drum cylinder center part, the drum cylinder center direction (wide arrow B
Direction), the base plate 3 has a circular locking hole 4 formed therein.

Reference numeral 5a denotes a cylindrical shaft fixing portion fixed to the braking drum 1, and an inserting portion 7a at one end of the fixing portion main body 6 is formed so that it can be fitted into the locking hole 4 of the braking drum 1. Has been done. In the fixed portion main body 6 near the insertion portion 7a,
A projecting portion 8 protruding outward in the radial direction is formed over the entire circumference, and the braking drum 1 is fixed to the fixing surface 8a on the insertion portion 7a side.
To support. The braking drum 1 and the shaft fixing portion 5a are coaxially centered and held, and are fixed by brazing using, for example, copper or the like to form an integral braking drum can.

A shaft mounting hole 14 through which a rotation transmission shaft 16 to be described later can be inserted is formed in the shaft center portion of the fixed portion main body 6 so as to penetrate therethrough in the shaft center direction. A plurality of spline projections 13 are provided in the shaft mounting hole 14 in the vicinity of the fixed end of the braking drum 1.
Are formed in the shape of an internal gear with the longitudinal direction along the axis. That is, grooves are formed along the drum axis between the adjacent spline protrusions 13. Since these spline protrusions 13 are obtained by tooth profile punching in the axial direction, they can be processed relatively easily and inexpensively.

A blind plug mounting hole 15a for accommodating and holding a blind plug 15 is provided at an end of the insertion portion 7a on the side where the braking drum 1 is fixed.
Are formed. The blind plug 15 fitted in the blind plug mounting hole 15a is fixed to the insertion portion 7a by copper brazing or the like to close the shaft mounting hole 14, and the rotation transmission shaft 16 described later inserted in the shaft mounting hole 14 is a drum cylinder. Prevents penetration in the axial direction.

On the other hand, 16 is a rotation transmission shaft for transmitting a rotational force to and from the braking drum 1. In the vicinity of the insertion end of the shaft body 17, a plurality of spline projections 18 are arranged in the longitudinal direction. It is formed in the shape of an external gear along the core. When the rotation transmission shaft 16 is inserted into the shaft mounting hole 14 of the braking drum cambi (the direction of arrow C), these spline projections 18 are formed.
By engaging with the groove between the spline protrusions 13, the rotation transmission shaft 16 is locked to the braking drum cam in the direction around the drum cylinder center.

When the above-described braking drum cambi is used in a bush cutter, a braking shoe (not shown) is connected to the driving side of the engine, for example, while the main body of the rotation transmitting shaft 16 is the driven side, for example. 17 A grass cutting blade (not shown) is connected to the end portion on the driven side.

Generally, since the price of a brush cutter used for mowing work is relatively low, a brake drum canbi used as a component of the brush cutter is also required to have a low manufacturing cost. However, in the conventional braking drum cambi, the blind plug 15 which is a separate component is required as the retaining portion. Further, it is necessary to perform a grinding process for forming the blind plug mounting hole 15a. Further, the blind plug 15 mounted in the blind plug mounting hole 15a must be fixed by, for example, copper brazing. Therefore, as part of the reduction in the manufacturing cost of the braking drum canbi, there has been a demand for inexpensive construction of the retaining portion.

On the other hand, when the brush cutter is used, the braking drum canbi rotates at about 3000 to 5000 rpm. Due to the vibration generated at this time, the copper solder made of a material different from that of the shaft fixing portion 5a may peel off, and the blind plug 15 may drop from the blind plug mounting hole 15a. As a result, the tip of the rotation transmission shaft 16 and the blind plug 15 enter the braking drum 1 (in the direction opposite to the wide arrow B), and the braking shoe and other parts are damaged.

By the way, as a rotation transmission shaft bearing structure, there is one disclosed in Japanese Patent Application Laid-Open No. 2-256911.
In this rotation transmission shaft bearing structure, a shaft mounting hole is formed in the shaft fixing portion provided in the drum, and the outer peripheral surface of the rotation transmission shaft is supported in the shaft mounting hole so as to be rotatable in the radial direction. Further, a steel ball is fitted in the vicinity of the tip in the shaft mounting hole, and the tip surface of the rotation transmitting shaft is supported by the steel ball in the thrust direction and is in sliding contact in the radial direction.

Further, Japanese Utility Model Laid-Open No. 53-37881 discloses a shaft fixing structure. With this shaft fixing structure, when the shaft having the knurled protrusion on the outer surface is mounted in the shaft mounting hole having the axial groove on the inner surface, the groove is crushed by the knurled protrusion and the shaft is fixed to the shaft mounting hole. It has become so.

[0012]

However, in the rotation transmission shaft bearing structure disclosed in Japanese Patent Laid-Open No. 2-256911, the drum cannot be thrust-supported by the tip of the rotation transmission shaft without the steel balls. It is necessary to machine the shaft mounting hole in a structure that allows steel balls to be fitted. Further, since the steel ball and the shaft fixing part are separate parts, there is a problem that the number of parts is correspondingly increased and a ball mounting work is also required.

On the other hand, the braking drum is a consumable item, and it may be necessary to disassemble and assemble it for maintenance. However, in the shaft fixing structure disclosed in Japanese Utility Model Laid-Open No. 53-37881, when the shaft is mounted in the shaft mounting hole, the groove portion is crushed by the knurled protrusions and the shaft is fixed in the shaft mounting hole. Therefore, when disassembling it and reassembling it, the shaft will be easier to pull out and spin more easily. Therefore, there is a problem in that once assembled, individual parts cannot be replaced.

The present invention has been made in view of the conventional problems, and it is possible to reliably prevent the rotation transmission shaft from penetrating through the shaft mounting hole of the shaft fixing portion, and to disconnect at a very low processing cost. It is an object of the present invention to provide a structure for preventing the rotation transmission shaft of a braking drum from slipping off that can form a stopping portion.

[0015]

In order to achieve the above object, a rotation transmitting shaft retaining structure for a braking drum according to the present invention is provided in a drum cylinder core portion of the braking drum, and a shaft mounting hole is provided in the drum cylinder core. A shaft fixing portion formed by penetrating in the direction,
An engagement groove portion having a groove formed along the drum cylinder center near one end of the shaft mounting hole, a rotation transmission shaft mounted in the shaft mounting hole of the shaft fixing portion, and provided on the outer periphery of the tip end portion of the rotation transmission shaft. The
The rotation transmission shaft is provided with the engagement groove portion of the shaft fixing portion and the engagement projection portion that is detachably fitted, and the engagement groove portion of the portion located at the tip of the attached rotation transmission shaft is preliminarily pressed and deformed to drum the rotation transmission shaft. It is configured to have a retaining portion that locks in the direction of the cylinder center.

[0016]

In the rotation transmitting shaft retaining structure of the braking drum according to the present invention, the retaining groove is formed in advance by pressing and deforming the engagement groove portion near one end of the shaft mounting hole. There is. By simply filling the engaging groove portion in this way, the retaining portion is made relatively strong with the same kind of material that is easily compatible with each other. Therefore, it is easy to form the retaining portion, and the retaining portion does not fall off due to, for example, vibration during rotation driving.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below in detail with reference to the accompanying drawings. 1A and 1B show a shaft fixing portion used in a braking drum canbi according to an embodiment of the present invention. FIG. 1A is a front view, FIG. 1B is a side sectional view, and FIG. 2 is a state explanatory view showing a state of a side cross section in which an embedded portion is provided at one end of the shaft fixing portion of the braking drum can and a rotation transmission shaft mounted on the shaft fixing portion. FIG. 3 is a shaft fixing of the braking drum can. FIG. 4 is a front view showing a state in which an embedded portion is provided at one end of the portion, and FIG. 4 is an enlarged view of a main portion in FIG. In these figures, the same reference numerals are used for the elements common to the conventional braking drum cambi shown in FIGS. 5 and 6, and the detailed description thereof will be omitted. In addition, the constituent elements having the same functions as those of the conventional braking drum canbi have the same numeral symbols and are used without the suffix.

As shown in FIGS. 1 (a) and 1 (b), the shaft fixing portion 5 used in the braking drum cambi according to this embodiment is basically the same as the conventional shaft fixing portion 5a shown in FIG. The structure is almost the same, and the structural difference from the conventional shaft fixing portion 5a is that the insertion portion 7 side from the protruding portion 8 to the tip of one end of the fixing portion main body 6 has a blind plug mounting hole like the conventional example. That is, 15a is not provided.

Here, ten spline protrusions 1 are provided.
3 is provided, and the spline groove portion 13 has a groove formed along the drum tube center between the adjacent spline projection portions 13.
a (an example of an engaging groove portion) is formed. The spline projections 18 of the rotation transmission shaft 16 (see FIG. 2) inserted into the shaft mounting holes 14 are inserted into the spline groove portions 13a.
The rotation transmission shaft 1 is formed by detachably fitting (an example of the engaging protrusion).
6 is locked around the drum cylinder center.
Further, the braking drum 1 and the shaft fixing portion 5 are held in a coaxially centered state in advance, and are fixed by brazing using, for example, copper or the like to form an integrated braking drum cambi (see FIG. 2). ing.

The braking drum cambi of this embodiment is constructed as described above. Next, the operation of providing the retaining portion of the present invention on the shaft fixing portion 5 of the braking drum cambi will be described below with reference to FIGS. 2 to 4. First, the fixing portion main body 6 and the protruding portion 8 of the shaft fixing portion 5 are held by the fixing portion holding jig 9 (indicated by a two-dot chain line in FIG. 2). In this state,
The tip of the insertion portion 7 protruding from the front side of the shaft locking hole 4 is pressed in the direction of the wide arrow B by a prismatic press rod 11 (shown by a two-dot chain line in FIG. 2).

As a result, the distal end of the insertion portion 7 is plastically deformed in the axial direction and is depressed to form the crush groove 19. Here, the crush groove 19 has a substantially square shape in front view (see FIGS. 3 and 4) when viewed in the axial direction (the direction of the wide arrow B in FIG. 2) corresponding to the outer shape of the press rod 11. 20 in each figure
Is an embedding portion (an example of a retaining portion) formed by embedding the spline groove portion 13a from the crushed portion of the insertion portion 7.

When the rotation transmission shaft 16 is inserted in the direction of arrow C (see FIG. 2) into the shaft mounting hole 14 of the shaft fixing portion 5 in which the embedded portion 20 is formed as described above, first, the spline projection 18 is formed.
Fits into the spline groove portion 13a of the shaft fixing portion 5, and the rotation transmission shaft 16 is locked in the direction around the drum cylinder center. And
When the tip of the spline protrusion 18 engages with the embedded portion 20,
The rotation transmission shaft 16 is prevented from coming off in the direction of the drum cylinder center.

As described above, according to the present embodiment, the plastic deformation at this time is performed by a simple operation such as pressing and deforming the end portion of the shaft fixing portion 5 of the braking drum canbi on the braking drum side using the press rod 11. Since the spline groove portion 13a is filled with the embedded portion 20 to form a retaining portion, the retaining portion can be easily provided. Further, unlike the conventional example, it is not necessary to form another component necessary for forming the retaining portion, a mounting hole for providing the other component at the end portion of the shaft fixing portion on the braking drum side, or the like. Therefore,
Compared with the conventional example, the braking drum cambi of this embodiment has an advantage that the retaining portion can be configured extremely easily and the manufacturing cost is extremely low.

The embedding portion 20 of this embodiment is formed integrally by plastically deforming a part of the shaft fixing portion 5, and is made of the same material as the shaft fixing portion 5. Therefore, it is easy to fit in with the spline protrusion 13 and the fixed portion main body 6. Furthermore, during mowing work with a brush cutter, the thrust force received from the tip of the rotation transmission shaft 16 to the embedding portion 20 is generally not so large, so that the embedding portion 20 secures the rotation transmission shaft 16 in the drum cylinder center direction. It is a structure that is too much to be locked in.

In this embodiment, the braking drum canbi is used in which the braking drum and the shaft fixing portion, which are individually manufactured, are later fixed to each other to form an integral body. However, for example, a round bar-shaped steel material is carved out. It can also be applied to a braking drum canbi having a relatively high strength, which is manufactured by an integrated manufacturing method such as a grinding manufacturing method for obtaining a finished product by processing or a forging manufacturing method for obtaining a finished product by performing a forging step of integral molding a plurality of times.

Further, in the above-mentioned embodiment, the retaining portion is provided at the end portion of the shaft fixing portion on the side where the braking drum is fixed, with respect to the previously integrated braking drum can. Alternatively, the shaft fixing portion and the braking drum may be integrated in a later process to form a braking drum can.

In the above embodiment, ten spline protrusions are provided to form the engaging groove portion of the shaft fixing portion, but the number and shape thereof are not limited, and the rotation transmitting shaft is not limited. Anything that can lock the drum in the direction around the drum cylinder center may be used. That is, the engagement groove portion can be formed in, for example, a quadrangular shape when viewed in the axial direction. Correspondingly, the engagement projection of the rotation transmission shaft may be shaped to fit into the engagement groove of the shaft fixing portion along the axis.

Further, in the above-mentioned embodiment, the press rod which forms a crushed groove having a rectangular shape when viewed in the axial direction is used. Shaped press rods can also be used.

[0029]

Since the rotation transmission shaft retaining structure for the braking drum according to the present invention is configured as described above, the engaging groove portion of the portion located at the tip of the mounted rotation transmission shaft is pressed and deformed. With such a simple processing operation, the retaining portion can be made relatively strong from the same type of material that is easily compatible with each other. Therefore, for example, since the retaining portion does not fall off due to vibration during rotation driving,
The rotation transmitting shaft is securely locked in the axial direction by the retaining portion. In addition, the formation of the retaining portion can be performed very easily, and the separate component that constitutes the retaining portion, the structure of the shaft fixing portion for attaching the separate component, and the work of attaching the separate component are not required. As a result, the retaining portion can be configured with a low number of parts and good workability. That is, the rotation transmission shaft can be reliably prevented from penetrating through the shaft mounting hole of the shaft fixing portion, and the rotation transmission shaft retaining structure for the braking drum described above can be realized at an extremely low processing cost. Further, when the rotation transmitting shaft is mounted in the shaft mounting hole of the shaft fixing portion, the engaging projection and the engaging groove are merely fitted together and neither is deformed. Disassemble the braking drum
It is possible to assemble and replace parts.

[Brief description of drawings]

1A and 1B are views showing a shaft fixing portion used in a braking drum canbi according to an embodiment of the present invention, wherein FIG. 1A is a front view and FIG. 1B is a side sectional view.

FIG. 2 is a state explanatory view showing a state of a side cross section in which an embedded portion is provided at one end of a shaft fixing portion of a braking drum canbi and a rotation transmission shaft mounted on the shaft fixing portion.

FIG. 3 is a front view showing a state in which an embedded portion is provided at one end of a shaft fixing portion of a braking drum cambi.

FIG. 4 is an enlarged view of a main part in FIG.

FIG. 5 is a state explanatory view showing a state of a side cross section in which a blind plug is provided at one end of a shaft fixing portion of a conventional braking drum cambi, which is an example of the background of the present invention, and a rotation transmission shaft mounted on the shaft fixing portion. It is a figure.

FIG. 6 is a front view showing a state in which a blind plug is provided at one end of a shaft fixing portion of a conventional braking drum cambi.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Braking drum 5 Shaft fixing part 13a Spline groove part (engagement groove part) 14 Shaft mounting hole 16 Rotation transmission shaft 18 Spline projection part (engagement projection part) 19 Crush groove 20 Embedded part (prevention part)

Claims (1)

(57) [Claims] 1. A brake drum is provided at a drum cylinder center portion of the braking drum,
A shaft fixing portion having a shaft mounting hole penetrating in the drum cylinder center direction, an engagement groove portion having a groove formed along the drum cylinder center near one end of the shaft mounting hole, and a shaft fixing portion. The rotation transmission shaft to be mounted in the shaft mounting hole of the rotation transmission shaft, and the engagement projection provided on the outer circumference of the tip end portion of the rotation transmission shaft and detachably fitted to the engagement groove portion of the shaft fixing portion. A retaining portion for retaining the rotation transmission shaft of the braking drum, characterized in that the engagement groove portion of the portion located at the tip of the transmission shaft is preliminarily pressed and deformed to form a retaining portion for retaining the rotation transmission shaft in the drum cylinder center direction. Construction.