JPS6132146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mounting device for a printing wheel for a serial printer, which has a number of spokes extending radially from a central portion, each spoke having one or several type characters.

Conventionally, type wheels, type balls, type pallets, etc. have been used as type assemblies in serial printers, but these are generally attached to the rotating shaft for type selection with nuts, screws, retaining rings, etc., and they are attached and removed using screws. Requires a turn, spanner or special tool. On the other hand, a mounting device has already been proposed that incorporates special parts for mounting and fixing, and does not require the use of tools for mounting and dismounting. For example, Japanese Patent Application Laid-Open No. 70017/1983 proposes a printing wheel mounting device in which a spring, pin, locking piece, etc. are provided on a rotary shaft for character selection. but,
This mounting device has a complicated structure, and has the disadvantage that play occurs in the axial direction of the print wheel, making it difficult to accurately position the print wheel. Furthermore, there is a device in which a rotating shaft for type selection is inserted and a cylindrical portion fixed to a boss portion of a print wheel is tightened from the outside with a spring, or a rotating shaft for type selection is elastically press-fitted. In all of these devices, the axial position of the print wheel is unstable, and there is a possibility that the print wheel may come off forward due to repeated printing.

The present invention aims to obviate the above-mentioned drawbacks in conventional print wheel mounting devices. Embodiments of the invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, a printing wheel 1 includes a boss portion 2 and a number of spokes 3 extending radially from the boss portion 2, and a type 4 is provided at the tip of each spoke 3. This printing wheel 1
, the clamp disk 5, the setter 6, and the knob 7 are integrally assembled at the factory as shown in FIG. 1 to form a printing wheel unit. The boss portion 2 of the print wheel 1 has a center hole 2A, and a print wheel positioning projection 8 is provided on the side opposite to the clamp disk 5.

Clamp disk 5 as a first engagement member
is a cylindrical portion 9 that fits into the center hole 2A of the boss portion 2.
and a print wheel positioning hole 10 into which the projection 8 of the boss portion 2 is fitted. Further, the clamp disk 5 has positioning protrusions 11 and 12 at diametrically opposed positions on the opposite side of the printing wheel 1, and is elastically formed on the outer periphery on a diameter perpendicular to the diameter connecting the positioning protrusions 11 and 12. The locking arms 13 and 14 are provided with locking arms 13 and 14. As shown in FIG. 2, these locking arms have a shape that first curves downward and then curves upward, and the lower side of the upwardly facing free end portion is tapered.

The setter 6 has three protrusions 15 extending in the axial direction at equal intervals, and a setter groove 16 provided inside between these protrusions.

The knob 7 has an elastic knob locking arm 17 that is to be locked in the setter groove 16 of the setter 6, and the setter 6.
It has a groove 18 into which the protrusion 15 fits.

On the other hand, the type selection rotary shaft 19 has the first
A receiving plate 20 as a second engaging member that engages with the engaging member is fixed to this receiving plate 20, and positioning recesses 21 and 22 to be engaged with the positioning protrusions 11 and 12 of the clamp disk 5 as well as the engaging members. Stop arm 13,1
4 locking holes 23 and 24 to be engaged.

The cylindrical portion 9 of the clamp disk 5 is passed through the center hole 2A of the boss portion of the printing wheel 1 and the setter 6 bonded to the boss portion by adhesive or ultrasonic welding, and the knob 7 is inserted into the tip of the cylindrical portion 9 through which the setter 6 is bonded by adhesive or ultrasonic welding. Fit it. In that case, the print wheel positioning protrusion 8 of the boss portion 2 is connected to the positioning hole 1 of the clamp disk 5.
0, and then insert the locking arm 17 of the knob 7 into the setter groove of the setter between the inside of the setter 6 and the cylindrical portion 9 of the clamp disc 5, and at the same time, insert the protrusion 15 of the setter into the corresponding position of the knob 7. Groove 1
8. In this way, the print wheel 1, clamp disk 5, setter 6, and knob 7 are formed as an integral unit as described above, but this is done at the factory.

The above-mentioned printing wheel unit is slid along the extension of the rotating shaft 19 for type selection, which is set upright in the center of the receiving plate 20, and the positioning protrusion 1 provided on the receiving plate 20 is inserted.
1 and 12 are engaged with the positioning recesses 21 and 22 of the receiving plate 20. Furthermore, by pushing in the printing wheel unit, a locking arm 13 is formed elastically.
14 has a tapered portion on the lower side of its free end that slides on the inner surface of the outermost edge of the locking holes 23 and 24 of the receiving plate 20, passes through the locking hole, and then bounces elastically to the position shown in FIG. As shown, the tip of each locking arm has a locking hole 23,
24, thereby preventing axial movement of the print wheel unit. In this case, each part of the print wheel unit is located on the same center line with respect to the rotation axis 19. 31 shown in FIG.
It is a printing hammer.

As described above, by fitting the print wheel positioning protrusion 8 into the positioning hole 10, the relative position between the print wheel 1 and the clamp disk 5 is determined, and the positioning protrusions 11 and 12 are further engaged with the positioning recesses 21 and 22. By doing so, the relative position of the clamp disk 5 with respect to the receiving plate 20 and therefore with respect to the rotary shaft 19 for character selection is determined. In this case, by making the dimensions of the protrusion and the recesses 11, 21 and 12, 22 different, it is possible to prevent attachment errors. In this way, the relative position of each character 4 of the printing wheel 1 with respect to the axis of rotation 19 is finally determined. The engagement between the positioning protrusions 11 and 12 and the positioning recesses 21 and 22 also serves to transmit torque from the receiving plate 20 to the clamp disk 5.

Locking hole 2 into which the tips of locking arms 13 and 14 lock
By adding elastic members to the edges of 3 and 24,
It is possible to compensate for variations in the machining dimensions of parts.

The printing wheel unit can be easily removed by pulling the knob 7, as the locking arms 13 and 14 are elastically bent and disengaged from the locking holes 23 and 24.

In the embodiment shown in FIG. 3, the locking arms 13' and 14' face inward and lock onto the radially inner side of the locking hole, and all other points are the same as in FIG. This is the same as shown in FIG.

In the embodiment shown in FIG. 4, an elastic leaf spring 29 is attached to the receiving plate 20, and a locking arm 30 of the clamp disc is locked to this. In this case, the locking arm 3
0 need not be formed elastically.

As described above, in the present invention, attaching and detaching the printing wheel does not require a special tool and can be done relatively easily.Furthermore, since the axial position of the printing wheel is regulated, the printing wheel is not far from the rotation axis during printing. It has the feature of not slipping out and providing stable engagement. Although the present invention has been described with respect to a disk-shaped printing wheel, the present invention is not limited thereto, and can also be applied to, for example, a tea cup-shaped printing wheel.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a printing wheel unit mounted on a rotating shaft using the mounting device according to the present invention, and FIG. 2 is an exploded perspective view of each part shown in FIG. 1.
FIG. 3 is a sectional view similar to FIG. 1 showing another embodiment of the mounting device, and FIG. 4 is a partial view showing still another embodiment. 1... Printing wheel, 2... Boss portion, 3... Spoke, 4... Type, 5... Clamp disk,
11, 12... Positioning protrusion, 13, 14... Locking arm, 19... Rotating shaft for type selection, 20... Receiving plate, 21, 22... Positioning recess, 23, 24...
...Latching hole.

Claims (1)

[Claims] 1. In a mounting device for attaching a print wheel for a serial printer, which has a large number of spokes extending radially from the center and each spoke is provided with one or several type characters, to a rotary shaft for type selection, A first engaging member that is separate from the printing wheel and is attached to the printing wheel, and a second engaging member that is fixed to a rotating shaft for character selection, and the first engaging member includes: a corresponding positioning member that engages with the positioning member provided on the print wheel; a protrusion that fits into and is fixed to a center hole provided in the boss portion of the print wheel; and a protrusion on the opposite side of the print wheel as positioning means in the rotational direction. and a locking arm elastically formed separately from the positioning projection as a positioning means in the axial direction, and the second engaging member has a positioning means for positioning the first engaging member. a positioning engagement part that engages with the protrusion;
A mounting device comprising: an engaging portion that engages with the locking arm.