JPH10148214A - Driving force transmission device - Google Patents

Abstract

[PROBLEMS] To easily assemble a rotating shaft and a rotating member, to easily obtain a center of rotation of the rotating shaft and the rotating member after the assembly, and to transmit a driving force to another driving force transmitting means. Provided is a driving force transmission device capable of transmitting power without transmission. A fitting projection at an end of a rotating shaft is inserted or press-fitted into an outer fitting recess of a rotating member. Rotary axis 5
Numeral 0 has both ends of the rotating member 60 by the fitting margins 51 and the cylindrical portions 53 formed at both ends of the D-cut surface 52 of the fitting convex portion 54, whereby the rotating shaft 50 and the rotating member 60 always have the same rotation center. Get. The D-cut surface 52 and the D-cut wall surface 62 form a loose engagement with a clearance fit tolerance. This makes it easy to assemble the rotating shaft and the rotating member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force transmitting device integrally formed by fitting a rotating shaft and a rotating member.

[0002]

2. Description of the Related Art Conventionally, a shaft member 1 as shown in FIG.
There is a driving force transmission device composed of a rotating member 20 and a driving member 20. As shown in FIG. 1B, one shaft member 10 is inserted into one end or both ends of a rotatable round bar member and has an arbitrary length and the same rotation center as the shaft member 10 (or an insertion margin). Press-in fee)
11 and a fitting portion 13 having a cut D-cut surface 12 are formed. The other rotating member 20 is
(c) as shown in FIG.
Outer fitting concave portion 2 having close contact margin 21 and D-cut surface 22 inside
3 is formed at the center.

As shown by arrows A in FIGS. 1B and 1C, the fitting portion 13 of the shaft member 10 is inserted or press-fitted into the outer fitting recess 23 of the rotating member 20 to rotate with the shaft member 10. When the member 20 is integrated, the shaft member 1 is formed by the D-cut surfaces 12 and 22.
The rotation member 20 and the rotation member 20 are configured to be relatively unable to idle.

The driving force from the shaft member 10 to the rotating member 20 is
The transmission is performed by pressing and rotating the D-cut surface 22 provided inside the outer fitting recess 23 of the rotating member 20 by the D-cut surface 12 provided in the fitting portion 13. In addition, the driving force from the rotating member 20 to the shaft 10
The cut surface 22 is transmitted by pressing and rotating the D-cut surface 12 of the shaft member 10. As described above, the D-cut surfaces 12 and 22 enable mutual transmission of the driving force.
Such a driving force transmission device is used, for example, in a paper transport mechanism of a printing device or the like.

FIG. 4 is a side view showing a configuration of a main part of the printing apparatus. The printing device shown in FIG.
And a platen roller 32 are opposed to each other, and a pair of transport rollers 33 (a drive transport roller 33 a and a driven transport roller 33 a).
The paper 34 is conveyed to the opposing portion of the print head 31 and the platen roller 32 by b), and is repeatedly advanced and retracted a plurality of times as shown by an arrow B in the drawing to add three colors of magenta, cyan, and yellow (or to add more colors). 4 colors) are printed and overlaid. The three color (or four color) inks are applied to the ink ribbon 35 in an area corresponding to the size of the sheet in a plane-sequential manner. The ink ribbon 35 is wound around a holding reel 36 of a ribbon cassette, and the ink is thermally transferred to the paper 34 by the print head 31 while being wound clockwise on the take-up reel 37 as shown by an arrow C in the drawing. You.

FIG. 5A is a side view showing the configuration of a drive unit for driving the transport roller 33a of the transport roller pair 33, and FIG. 5B is a perspective view thereof. As shown in FIGS. 7A and 7B, the shaft member 10 of the above-described driving force transmission device forms a shaft of the driving conveyance roller 33a.

FIGS. 6A and 6B are enlarged views showing the structure of the driving force transmitting device incorporated in the driving mechanism of the printing apparatus in more detail. FIG. 6A is a front sectional view, and FIG. It is the side view.

The drive mechanism shown in FIGS. 5 (a) and 5 (b) and FIGS. 6 (a) and 6 (b) includes a worm gear 41 connected to a motor 40 via a drive system, a pulley gear 42 meshing with the worm gear 41, The pulley 43 is integrated with the belt, the belt 44 is engaged with the pulley 43, and the rotating member (pulley) 20 and the shaft 10 of the driving force transmitting device shown in FIG. You.

If the transport rollers 33a have rotation irregularities, they appear as variations in the amount of paper 34 transported. In the full-color printing (printing), as described above, the paper 34 is advanced and retreated a plurality of times so that three colors (or four colors)
It is necessary to print the ink three times (or four times) with small-diameter print dots at the same position on the paper surface. However, in such a full-color printing machine or the like, if the conveyance amount of the paper 34 becomes uneven, This may cause printing deviation of the ink to be overcoated. If there is even a slight print shift, color unevenness and moire (unique stripe pattern unevenness) occur, and the quality of the printed image is greatly reduced. Therefore, the above drive mechanism is required to have high-precision rotation characteristics.

In general, the driving force transmission device shown in FIG. 3A, which constitutes the driving mechanism shown in FIGS. 5A and 5B, improves the assemblability when each part is supplied to an assembling process and assembled. In consideration of this, as shown in the enlarged views of FIGS. 6A and 6B, the shape of the insertion portion 13 of the shaft member 10 and the shape of the external fitting recess 23 of the rotating member 20 are different from each other after the D-cut after assembly. An air gap E is provided between the surface portions 12 and 22. This achieves good assemblability. The rotation center F is obtained by the insertion margin 11 (21) having the same rotation center as the shaft member 10.

[0011]

However, at the time of actual driving by the above-mentioned driving mechanism, tension T is applied to the belt 44 as shown in FIGS. 5 (a) and 5 (b).
Due to the tension T, the rotating member 20 is bent outward and tilted by an amount corresponding to the space E as shown by an arrow H in FIG. 6A, and the tilting causes the center F of the rotation shaft to be eccentric. When the center of the rotation shaft is eccentric, the rotation radius of the belt 44 over the rotation member 20 slightly changes. This change in the radius of rotation causes uneven rotation in the transmission of the rotational driving force to the rotating mechanism unit after the driving force transmitting device, causing unevenness in the paper transport amount in a printing device or the like.

Also, if the insertion during assembly is loose,
When the rotating member 20 is inclined in the H direction, the rotating member 20 is shifted outward by the belt 44 with the tension T as indicated by an arrow J in FIG.

However, in order to prevent the rotation unevenness from occurring, the fitting portion 1 including the press-fit margin 11 and the D-cut surface 12 having the same rotation center F as the shaft member 10.
3 (see FIG. 3 (b)), an outer fitting recess 23 having a D-cut surface 22 having a high-precision rotation center F 'and a high-precision fitting accuracy is formed in the rotating member 20 (FIG. 3 (c)). )), If an attempt is made to form a firm press-fit assembly having no gap E and no play, if the press-fit assembly is performed, the direction of the assembling surface of the D-cut surfaces 12 and 22 of the fitting portion 13 and the outer fitting concave portion 23 is shifted. In this case, the corner 14 (see FIG. 3B) at the end of the D-cut surface 12 of the fitting portion 12 is caught on the D-cut surface 22 provided in the outer fitting concave portion 23, causing scratches. ,
This causes play and looseness of the press-fitting portion. When loosening occurs, rotation unevenness is caused in the same manner as described above, and therefore, it is necessary to precisely assemble the assembly direction at the time of press-fitting assembly. In addition, considerable force is required during press-fitting. In this case, there was a problem because the assemblability was poor.

In general, the shaft member 10 is formed by performing a cutting process using a lathe, so that the shaft center F easily comes out at the time of machining, and even when the D-cut surface 12 is milled, the shaft end whose center is already determined is determined. The shaft center C
There is no effect on the position accuracy. However, since the rotating member 20 is a resin molded product, the accuracy of the shape after molding is determined by the accuracy of the mold. However, when making this mold, it is extremely difficult to properly center and form a recess having a D-cut surface, such as the external fitting recess 23 of the rotating member 20,
Even if a high fitting accuracy is provided, the rotation center alone cannot be correctly determined. Dare to seek the correct centering is disadvantageous in terms of cost, since it requires precise and time-consuming technology, which results in a large increase in cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and facilitates assembling a rotating shaft and a rotating member, and easily obtains a rotating center of the rotating shaft and the rotating member after the assembly. An object of the present invention is to provide a driving force transmission device capable of transmitting an applied driving force to another driving force transmitting means without rotation unevenness.

[0016]

The construction of the driving force transmitting device according to the present invention will be described below. The driving force transmission device of the present invention includes:
An arbitrary length fitting allowance formed at one or both ends of a rotatable element shaft and having the same rotation center as the element shaft, a non-rotating cutting surface for driving force transmission, and a side provided with the cutting surface A rotating shaft having a fitting projection formed of a centering portion having the same rotation center as the elementary shaft and protruding from a shaft end of the shaft, a first fitting hole externally fitted to the fitting allowance, and the center. The second that fits externally to the extension
And a cavity located between the second outer fitting hole and the first outer fitting hole and having a shape corresponding to the cutting surface and having a wall surface facing the cutting surface. A rotary member having a concave portion, and the rotary shaft and the rotary member are integrally formed by fitting the fitting convex portion into the outer fitting concave portion.

The outer fitting concave portion and the fitting convex portion are formed, for example, with the accuracy that the fitting is performed by insertion or press fitting. Further, the fitting accuracy between the fitting allowance and the first outer fitting hole is configured with a fitting tolerance, for example, as described in claim 3. Further, the fitting accuracy between the centering portion and the second outer fitting hole is configured with a fitting tolerance, for example, as described in claim 4.
The fitting accuracy of the portion having the cutting surface and the portion of the cavity is configured, for example, with the tolerance of the hole of the clearance fit.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a perspective view of a driving force transmission device according to an embodiment, and FIGS.
Is an exploded view thereof. As shown in FIG. 1A, the driving force transmission device is composed of a rotating shaft 50 and a rotating member 60 integrally assembled.

As shown in FIG. 1B, the rotating shaft 50 has an arbitrary rotation center K at one end or both ends of a rotatable round rod-shaped shaft (element shaft). A fitting margin 51 having a length, and a D-cut surface (non-rotation cutting surface) 5 formed at the shaft end having the fitting margin 51 for transmitting a driving force.
2 and a cylindrical portion (centering portion) 53 having the same rotation center K as the shaft member 50 formed at the shaft end on the side where the D-cut surface 52 is provided. .

On the other hand, as shown in FIG. 3C, the rotating member 60 has a large fitting hole (first fitting hole) 61 which is fitted to the fitting margin 51 of the rotating shaft 50, and a rotating shaft 60. A small fitting hole (second fitting hole) 63 that fits outside the cylindrical portion 53 of the rotary shaft 50, and is located between the small fitting hole 63 and the large fitting hole 61. An external fitting recess 64 is provided which comprises a cavity having a correspondingly shaped D-cut wall surface 62.

In these, the fitting projection 54 of the rotating shaft 50 is
As shown by the arrow L in the figure, the outer fitting recess 64 of the rotating member 60 is provided.
As shown in FIG. 3A, the drive shaft is integrally formed with the rotary shaft 50 and the rotary member 60.

In this embodiment, the fitting between the D-cut surface 52 of the rotating shaft 50 and the D-cut wall surface 62 of the rotating member 60 has a hole tolerance of a clearance fit. The fitting of the parts is extremely easy. On the other hand, the fitting tolerance between the fitting margin 51 and the large fitting hole 61 and the fitting between the cylindrical portion 53 and the small fitting hole 63 are set to be suitable for the equipment. Therefore, assembly by relatively loose press-fitting or insertion is possible. Therefore, assembling of both members becomes easy as a whole.

As described above, the fitting protrusion 54 and the outer fitting recess 64 are provided.
Are formed with the accuracy that the fitting is performed by insertion or press fitting. Then, as described above, when the fitting convex portion 54 of the rotating shaft 50 is inserted or press-fitted into the outer fitting concave portion 64 of the rotating member 60 to integrate the two members, the respective D-cut surfaces 52 and 62 cause the two members to idle each other. It is configured to be impossible.

FIG. 2A is a front sectional view showing a state in which the driving force transmission device having the above-described structure is assembled to a paper transport mechanism or the like of a printing apparatus similar to that shown in FIG. )
Is a side view thereof. According to the driving force transmission device of the present embodiment shown in FIGS. 7A and 7B, when the rotating shaft 50 starts rotating, the driving force is applied to the fitting projection 5 of the rotating shaft 50.
The driving force is transmitted to the rotating member by pressing and rotating the D-cut wall surface 62 provided inside the outer fitting concave portion 64 of the rotating member 60 by the D-cut surface 52 provided on the rotating member 60.

At this time, with respect to the rotational movement of the rotating shaft 50,
The rotating member 60 is shown on both sides in FIGS.
As shown in (a), since it is supported by the fitting margin 51 and the cylindrical portion 53 having the same rotation center K as the rotation shaft 50,
A stable rotation center can be shared with the rotation shaft 50. That is, despite the fact that the hole tolerance M for the clearance fit is provided between the D-cut surface 52 of the rotating shaft 50 and the D-cut wall surface 62 of the rotating member 60, the hole tolerance M for the clearance fit is Does not cause the rotating member 60 to tilt in any direction due to the tension T applied to the rotating member 60. The hole tolerance M merely generates a slight difference in time until the locking of the two members in the rotation direction at the beginning of rotation.

Therefore, during the rotation of the rotating member 60, even if the radius of rotation of the belt 70 is small, the belt 70 can continue to rotate stably.
As a result, no irregularities occur in the drive transmission. For example, when used in the paper transport mechanism of the printing apparatus shown in FIG. And a high quality print image can be realized.

In the example of the above configuration, the case where the driving force is transmitted from the rotating shaft 50 to the rotating member 60 has been described. However, the present invention is not limited to this.
The same functions and effects can be obtained even when the driving force is transmitted to the motor.

Further, the driving force transmission device of the present invention can be applied to not only the above-described rotation driving force transmission mechanism of the printing apparatus but also any driving force transmission mechanism requiring high-precision rotation characteristics.

[0029]

As described in detail above, according to the present invention, the engaging portions formed by the cylindrical shaft and the round hole are formed at both ends of the D-cut surfaces of both the rotating shaft and the rotating member. Since the rotating member can be supported at both ends, the same rotation center of the rotating shaft and the rotating member after assembly can be reliably obtained. In addition, since the rotating member has both ends on the rotating shaft,
The engagement of the intermediate D-cut surface can be configured gently, so that the rotating shaft and the rotating member can be easily assembled, and the work efficiency of the assembling process is improved. In addition, since the rotation shaft and the rotation center of the rotation member can be kept the same, rotation unevenness does not occur in the transmission of the driving force from one member to the other member. In such a case, it is possible to eliminate the conventional unevenness of the paper transport amount, and therefore, it is possible to provide an image forming apparatus that performs high-quality printing without printing unevenness and color unevenness.

[Brief description of the drawings]

FIG. 1A is a perspective view of a driving force transmission device according to an embodiment, and FIGS. 1B and 1C are exploded views thereof.

2A is a front sectional view showing a state in which a driving force transmission device is assembled to a rotary drive mechanism of another device, and FIG. 2B is a side view thereof.

FIG. 3 (a) is a diagram showing a configuration of a conventional driving force transmission device,
(b) is a diagram showing the structure of the shaft, and (c) is a diagram showing the structure of the rotating member.

FIG. 4 is a diagram showing a configuration of a main part of a printing apparatus in which a conventional driving force transmission device is incorporated.

FIG. 5A is a side view showing a configuration of a driving unit for driving a driving conveyance roller of a conventional printing apparatus, and FIG. 5B is a perspective view thereof.

FIG. 6 is an enlarged view showing the configuration of a driving force transmission device portion incorporated in a driving mechanism of a conventional printing apparatus in more detail.
(a) is a front sectional view, and (b) is a side view.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 shaft material 11 insertion allowance (press-fit allowance) 12 D-cut surface 13 fitting portion 14 corner portion 20 rotating member 21 close contact allowance 22 D-cut surface 23 external fitting concave portion 31 print head 32 platen roller 33 (33a driven transport roller, 33b driven transport Roller) Conveying roller pair 34 Paper 35 Ink ribbon 36 Holding reel 37 Take-up reel 40 Motor 41 Worm gear 42 Pulley gear 43 Pulley 44 Belt 50 Rotation shaft 51 Fitting allowance 52 D cut surface (anti-rotation cutting surface) K Rotation center 53 Column portion (Centering portion) 54 Fitting convex portion 60 Rotating member 61 Large fitting hole (first fitting hole) 63 Small fitting hole (second fitting hole) 62 D-cut wall surface 64 External fitting concave portion M Gap fit Hole tolerance 70 belt T tension

Claims (5)

[Claims] 1. An arbitrary length fitting allowance formed at one or both ends of a free-rotating element shaft and having the same rotation center as the element shaft, a non-rotating cutting surface for transmitting driving force, and the cutting. A rotary shaft having a fitting projection formed of a centering portion protruding from the shaft end on the side where the surface is provided and having the same rotation center as the elementary shaft, and a first fitting externally fitted to the fitting margin A mating hole, a second fitting hole externally fitted to the centering portion, and a shape corresponding to the cutting surface positioned between the second fitting hole and the first fitting hole. A rotating member having an external fitting concave portion formed of a cavity having a wall surface facing the cutting surface, and the rotating shaft and the rotating member are integrally formed by fitting the fitting convex portion into the external fitting concave portion. A driving force transmission device characterized by being configured as follows. 2. The driving force transmission device according to claim 1, wherein the outer fitting concave portion and the fitting convex portion are formed with a precision in which the fitting is performed by insertion or press fitting. 3. The driving force transmission device according to claim 1, wherein the fitting accuracy between the fitting allowance and the first outer fitting hole has a fitting tolerance. 4. The driving force transmission device according to claim 1, wherein the fitting accuracy between the centering portion and the second outer fitting hole is configured with a fitting tolerance. 5. The fitting accuracy according to claim 1, wherein the fitting accuracy between the shaft portion having the cutting surface and the cavity portion is determined by a hole tolerance of a clearance fit. Driving force transmission device.