JPS6229272Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an expanding device for a ball chuck for a mechanical pencil.

A sharp shaft that obtains core clamping force by tensioning a chuck spring between a chuck body forming a trochanter seat and a chuck actuating body whose trochanter seat surface is an inclined surface. The construction of ball chucks for pencils is known in the art. In order to lose this core clamping force, a mutual positional relationship is established in which the chuck body is advanced further than the chuck actuating body against the chuck spring so as to eliminate the wedge effect due to the inclined surface of the chuck actuating body with which the trochanter contacts. This can be achieved by changing the However, when inserting a new lead from the lead tank into the chuck part, unless you expand it more aggressively and sufficiently, the lead will get caught in that part and will not be inserted smoothly.

The purpose of this invention is to actively retract the chuck actuating body to ensure that the chuck body expands sufficiently when the mutual positional relationship is changed such that the chuck body advances further than the chuck actuating body as described above. To provide a ball chuck expanding device capable of creating a margin for opening.

This invention will be explained based on the embodiment shown in FIG. 1. The chuck actuating body 2 of the ball chuck inserted into the shaft cylinder 1 is biased backward by the first spring 6 and can be moved back and forth by a certain distance. do. In this example, the chuck operating body 2 occupies a steady resting position by pressing the protrusion 3 formed on the outer surface of the chuck operating body 2 against the shaft cylinder stepped portion 1b, and from this steady resting position, the front end face 4 of the chuck operating body 2 It is possible to move forward between the collisions with the shaft cylinder stepped portion 1a. However, although not shown in the drawings, this may be restricted by forming the barrel stepped portion with which the front end surface of the protrusion 3 collides to face the barrel stepped portion 1b described above.

The chuck body 7 of the ball chuck has a chuck spring 8 and a trochanter 9 stretched between it and the chuck operating body 2.
It applies a tightening force to the chuck part in its steady state, and eliminates the tightening force on the chuck part when moving forward to change the mutual positional relationship with the chuck actuating body 2. In addition to making several cracks in the head to make it easier to open, a suitable self-expanding force is given in advance. As a means for forcibly expanding the chuck part, a protruding engaging part 10 is formed on the front end surface of the chuck body 7, and the other protruding engaging part 11 that cooperates with this is formed on the shaft cylinder 1 itself. Alternatively, it is formed into a sliding ring 17 that can move back and forth over a certain distance with respect to the shaft cylinder 1 (see Fig. 9-B). By allowing the protruding engaging portion 10 to rise above the protruding engaging portion 11, the chuck portion can be forcibly expanded.

The operation knob 1 is biased rearward by a second spring 14 and protrudes outward from the barrel 1 behind the chuck body 7.
A pressing member 12 is disposed at 3 so as to be movable forward and backward.
Numeral 15 denotes a long hole for guiding the operating knob 13, which is drilled in the barrel 1. However, the operating knob 13 may be projected from the rear end of the barrel 1 in accordance with a normal rear-end knock type.

In the first half of the forward movement of the operation knob 13, which is indicated by the arrow in FIG. In the latter half of the forward movement of the operating knob 13, as indicated by the arrow in FIG. This pressing arm piece 16 can be made to be superimposed on the inside of the chuck operating body 2 as shown in FIG. 4, or can be attached to the chuck operating body 2 as shown in FIGS. 5 and 6. It can also be integrally formed, in which case it can be superimposed on the outside or inside of the pressing member 12. 6 to 8, in which the pressing arm piece 16 is attached to the chuck operating body 2 and can be superimposed on the inside of the pressing member 12, correspond to FIGS. 1 to 3, respectively.

When the pressing arm piece 16 reaches the state shown in FIG. 3 where it overlaps the chuck operating body 2 or the state shown in FIG. 8 where it overlaps the pressing member 12, the pressing arm piece 16 loses its function as a pushing tool, and instead, The chuck body 7 can be pushed forward by the pressing member 12, and as a result, both the protruding engaging portions 10 and 11 can be completely engaged. On the other hand, since it forms a space that allows the chuck actuating body 2 to retreat, the first spring 6
The chuck actuating body 2 pushed by can be retracted a certain distance.

In addition, 18 in the figure indicates a core detent, which is attached to the slider 19 (No. 9-A) in order to attach it to the shaft cylinder 1.
(See Figure 9-B).

As is clear from the above explanation, while the arm piece 16 works as a pusher for the chuck operating body 2, the mutual positional relationship between the chuck operating body 2 and the chuck body 7 remains unchanged, and therefore, the core of the chuck portion is not changed. If the lead is bitten, the lead can be pushed out against the resistance of the lead detent 18, and if the lead is not eaten, the chuck moves forward with the chuck closed, but the arm piece 16 acts as a pusher for the chuck operating body 2. When the function of the chuck body 7 is lost and it overlaps with the other party, as mentioned above, the chuck body 7 is given enough room to expand due to the retreat of the chuck actuating body 2, so the chuck body 7 has a self-expanding force. Sufficient expansion can be achieved with the help of forced expansion means consisting of protruding engaging portions 10 and 11. From a centering point of view, this allows the extruded core to be retracted in the expanded state without being pulled back, and also prevents the new supply core from getting caught when inserted into the chuck. It is possible to achieve the intended purpose.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing the first embodiment of the present invention in the order of operation, and FIGS. 4 and 5 are cross-sectional views showing the second and third embodiments of the present invention, 6th
8 to 8 are sectional views showing the fourth embodiment in the order of operation, and FIGS. 9-A and 9-B are sectional views showing modifications of the tip portion. DESCRIPTION OF SYMBOLS 1... Shaft cylinder, 2... Chuck operating body, 7... Chuck body, 8... Spring for chuck, 9... Trochanter,
12...Press member, 13...Operation knob, 14...
Second spring, 16...pressing arm piece.

Claims (1)

[Scope of utility model registration request] The chuck actuating body 2 of the ball chuck fitted into the shaft cylinder 1 is biased backward by a first spring 6 and is movable back and forth over a certain distance, and the chuck body 7 of the ball chuck has a protruding engagement portion 10 on the front end surface. The chuck is attached to the chuck body 7 so as to be movable back and forth via a chuck spring 8 and a trochanter 9 stretched between the chuck body 2 and the chuck body 7. A pressing member 12 that can be moved back and forth by an operating knob 13 that is exposed outside the shaft cylinder 1 is disposed. Until it is blocked, it engages with either the chuck actuating body 2 or the pressing member 12, but when it is blocked, the engagement is released and the chuck actuating body 2 retreats and the chuck body 7 is further pushed by the pressing member 12. A pressing arm piece 16 having flexibility to enable the chuck body to move forward is provided, and another protruding engagement portion 11 is formed on the side opposite to the front end surface of the chuck body 7. Expansion of a ball chuck for a sharp pencil characterized in that when the chuck body 7 is further advanced, the protruding engaging part 10 of the chuck body 7 rises over the other protruding engaging part 11 and forcibly expands the chuck part. Opening device.