JPH0522600B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chuck body for a sharp pencil that allows good gripping and release of the lead.

This type of chuck body can be either an integrally molded product or an integrally joined product of multiple components, and in either case,
A proximal end that receives a spring that urges backwards and receives the thrust given by the notching action of the sharp pencil, and a tightening force directed toward the center obtained by converting the axial force of the spring. It includes a core holding part that is tightened by the core holding part, and an intermediate arm part that connects the two parts. In the case of a chuck body that is integrally molded, a jig is pressed against the front part of the chuck body with several vertical divisions, and the chuck body is deformed into an expanded shape. The shapes of the members are deflected so that the front part of the chuck body becomes expanded after being integrally joined. The desired core clamping is achieved by forcibly deforming the expanded core clamping part using the tightening force directed toward the center obtained by converting the axial force of the spring, and
Furthermore, the release of the lead was dependent on the restoring elastic force of the lead holding portion that was naturally generated by eliminating the above-mentioned tightening force.

The conventional chuck mechanism, which relies on the restoring elastic force and forced deformation of the chuck body, has the following drawbacks. One is that it takes much longer to force the chuck to close against the restoring elastic force of the chuck, so even if the chuck is sufficiently expanded at first, the degree of expansion may be gradually reduced. This is a problem of stagnation as the lead decreases and eventually the supply of lead from the lead tank gets stuck, making it impossible to replenish the lead smoothly. Another problem is that if you anticipate this fatigue and create a strong restoring elastic force, you will have to increase the strength of the spring to provide the core clamping force against it, making it difficult to operate the knob. In addition, the lead gnawing caused by the gripping teeth became stronger, and the space between the gripping teeth became completely filled with lead powder caused by the lead gnawing phenomenon, making it impossible to grip the lead with resistance to writing pressure. be.

Separately, the chuck body has a mating structure in which a plurality of chuck constituent pieces can swing at a swinging fulcrum formed on the facing surface of the proximal end of each chuck constituent piece, and the proximal end that is behind the swinging fulcrum. Some portions serve as converting portions that convert the thrust force into a clamping force directed toward the center. In this case, if the thrust from the knocking action of the sharp pencil is applied to the small-diameter proximal end to open the chuck, the contact area will naturally become small because the proximal end has a small diameter. Since the pressure per unit area had to be large, problems such as abrasion of the part or poor detachment were likely to occur.

The present invention has been made with the aim of eliminating this inconvenience, and the converting portion of the base end portion is either a large diameter portion that cooperates with the outer cylinder of the ball chuck, or an inclined portion that cooperates with the spring. This is a large diameter portion.

The present invention will be explained below with reference to the accompanying drawings.

FIG. 1 shows an example in which the chuck body 1 is applied to a ball chuck mechanism of a tip-notch type sharp pencil, and FIG. 2 shows an exploded perspective view of the chuck body 1 shown in FIG. 1. This chuck body 1 also has a proximal end portion 2 that receives a spring 8 that urges the chuck body 1 toward the rear.
c, and the core clamping part 2 which is tightened by the force in the center direction obtained by converting the axial force of the spring 8.
a and an intermediate arm portion 2b that connects both portions 2a and 2c. In the illustrated example, the two chuck constituent pieces 2, 2 have a mating structure that is swingable by swinging fulcrums 3 formed on the base end portions 2c, 2c of opposing surfaces.

Now, regarding the method of constructing the swinging fulcrum 3, as long as no misalignment occurs between the chuck constituent pieces 2, 2 when the chuck constituent pieces 2, 2 swing, it is sufficient to simply abut them.
As an example of this case, the swing fulcrum 3 is configured by line contact in Figures 5-A and 5-D, and by surface contact in Figures 5-B and 5-C. It shows. However, it is preferable to adopt means that can reliably prevent this deviation.
As shown in the figure, each chuck component piece 2,
A protrusion 3a and a seat 3 are formed on the flat surfaces on both sides of the core insertion grooves 4, 4 formed in the proximal ends 2c, 2c of 2, respectively.
b, or one proximal end 2c has two protrusions 3a, and the other proximal end 2c has two co-receiving seats 3b (not shown), and the protrusion 3a is the other protrusion 3b. Alternatively, as shown in FIG. 3, a highly flexible pin-shaped member 3c is implanted in the proximal end portions 2c, 2c of the two chuck component pieces 2, 2. , 3c are received by a seat 3d formed on the other base end 2c. The example shown in FIG. 4 in which both the protrusion 3a and the seat 3b are shaped like knife edges and are elongated in the lateral direction can more reliably prevent wobbling than the example shown in FIG. 2.

In the present invention, the two states of clamping and releasing the core are created by the swing of the chuck constituent pieces 2, 2 around the swing fulcrum 3, so the structure in which the chuck constituent pieces 2, 2 are joined together is basic. End portion 2c, 2
c In order to prevent the core holding parts 2a, 2a from not opening sufficiently due to collision between the two pieces, an appropriate gap should be provided between the chuck component pieces 2, 2, or the proximal ends 2c, 2c should be connected to the proximal end 2c. , 2c are provided with appropriate warpage.

In order to use such a chuck body 1 as a ball chuck mechanism, ball seats 5 are formed on the outer surfaces of the core holding parts 2a, 2a, and the chuck is connected by a spring 8 housed in an outer cylinder 7 having an inclined guide surface 6. The body 1 is urged backward. By doing so, the ball 9 housed in the ball receiving seat 5 is pressed against the inclined guide surface 6 of the outer cylinder 7, and the axial force of the spring 8 is converted into a tightening force directed toward the center. In this respect, the present invention is no different from the conventional method. However, instead of forcibly converting the core clamping parts 2a, 2a with clamping force to clamp the core as in the past, the swinging fulcrum 3
By applying a clamping force to the lead clamping parts 2a, 2a located at a distance from the core, the chuck components 2, 2 are rotated about the swing fulcrum 3 so that the lead clamping parts 2a, 2a are joined together. This is done by holding the material in place. Therefore, when the swing fulcrum 3 is a combination of the protrusion 3a and the seat 3b, the wear and tear on the swing fulcrum 3 caused by repeated swing movements is almost negligible;
There will be no problem of fatigue. Furthermore, even when the swing fulcrum 3 is formed of a highly flexible pin-shaped member 3c, the pin-shaped member 3c
By designing the pin-like member 3c to stand up almost straight, even if the core is held in the clamped state for a much longer time, the bending stress on the pin-shaped member 3c can be minimized. Therefore, the pin-shaped member 3
Sagging c is not a problem. Furthermore, unlike the conventional method, the core holding parts 2a, 2a are not forcibly deformed.
The force of the spring 8 also needs to be weak, and the knob operation can be done easily.

Next, when the user performs a knock operation to feed out the lead, a thrust force that resists the force of the spring 8 is applied, for example, via the pusher 10, and as a result, the chuck body 1 is pushed forward, which is different from the conventional method. It doesn't change. However, when the chuck body 1 moves forward under the thrust force of the pusher 10, the clamping force at the lead clamping part decreases, and in response to this, the lead clamping part automatically expands with the restoring elastic force developed. Therefore, unlike the conventional structure in which there is no need to provide the proximal end of the chuck with a function for expanding the core clamping part,
In the present invention, the base end 2c corresponding to the rear of the swing fulcrum 3,
The portion 2c is a conversion portion that converts the thrust force given by the pusher 10 into a tightening force directed toward the center, and actively expands the core holding portions 2a, 2a that are far away from the swing fulcrum 3.

The other party whose base end portions 2c, 2c corresponding to the rear of the swing fulcrum 3 cooperate to convert the above-mentioned thrust into a tightening force directed toward the center may be the pusher 10 itself, or in the case of a ball chuck, an external member. Tube 7 may also be used. Furthermore, it may be a spring 8. Base end portions 2c, 2c
The shapes of the parts are designed in accordance with the types and shapes of the cooperating pusher 10, outer cylinder 7, or spring 8, so that the above-mentioned thrust is decomposed to obtain a component force directed toward the center. In the illustrated example, the base end portions 2c, 2c that correspond to the rear of the swing fulcrum 3 directly cooperate with the pusher 10 to obtain a tightening force directed toward the center. The rear end edges of 2c and 2c can be pressed by an inwardly tapered surface 12 formed on the distal end annular portion 11 of the pusher 10, and in the example shown in FIG.
c A tapered surface 13 that is pressed by the inner edge of the annular tip portion 11 of the pusher 10 is formed at the rear. However, since both the inwardly tapered surface 12 and the tapered surface 13 have small diameters, the pressure per unit area during pressure welding becomes large, which has the drawback of easily causing problems such as wear and tear of the parts or poor detachment. .

Therefore, in the present invention, in order to reduce the pressure per unit area during pressure welding, when the chuck body 1 is pushed forward by the pusher 10, it cooperates with the outer cylinder 7 and the tail end of the spring 8. In order to obtain a tightening force directed toward the center, in the example shown in FIG. In the example shown in FIG. 5-C, a flange-like protrusion 16 that is pushed by the inwardly tapered surface 15 of the outer tube 7 is formed at the rear end of the base end portions 2c, 2c. Furthermore, in the example shown in FIG. 5-D, a projecting portion 18 having an inclined surface 17 pushed by the tail end of the spring 8 is formed at the rear end of the base end portions 2c, 2c. Whether it is the tapered bulge 14 shown in Fig. 5-B or the collar-like protrusion 16 shown in Fig. 5-C, the fifth
- Even with the overhanging part 18 in figure D, both base end parts 2
Since the diameter is larger than that of c and 2c, the pressure per unit area during pressure welding becomes smaller. In either case, the thrust when the knocking action is applied against the force of the spring 8 will produce a clamping force that is a component force directed toward the center, and the proximal end that is behind the swing fulcrum 3 will be 2c, 2
c are mutually displaced toward the center, so that the core clamping parts 2a, 2a, which are far apart from the swing fulcrum 3, are fully opened.

The lead clamping parts 2a, 2a in the expanded state return to the closed state by the force of the spring 8 by stopping the knocking operation and releasing the finger. At that time, if necessary, means for preventing the chuck components 2, 2 from slipping may be formed so that the grooves 4, 4 for inserting the cores are properly aligned. In FIG. 5-A, the rod-shaped projection 19 protruding from one chuck component 2 and the guide hole 20 of the other chuck component 2 into which the rod-shaped projection 19 is inserted are an example of the above-mentioned slippage prevention means. ing. Furthermore, if the swing fulcrum 3 is made up of a combination of a protrusion 3a and a catch 3b, the chuck constituent pieces 2, 2 are not tied together but simply put together, which is inconvenient in handling. , as shown in FIG. 5-A, an O-ring mounting groove 21 may be formed in the base end portions 2c, 2c, and they may be bound together with an O-ring 22, or the ring portion at the rear end of the spring 8 may be made of a hard material. Fitting portions 23, 23 that fit into the base end portions 2c, 2c may be formed.

Although the explanation up to this point has been based on the assumption that there are two chuck constituent pieces 2, 2, the chuck body 1 is composed of three or more chuck constituent pieces, and a swinging fulcrum is provided on the facing surface of the proximal end of each chuck constituent piece. The chuck component of the present invention can be formed into a mating structure that can swing, and the base end portion behind the swing fulcrum can be used as a conversion part that converts the thrust force into a tightening force directed toward the center. Needless to say, this can also be applied to cases where there are three or more 2's.

As is clear from the above description, in the chuck body of the present invention, the converting portion of the base end portion may be a large diameter portion that cooperates with the outer cylinder of the ball chuck, or an inclined large diameter portion that cooperates with the spring. As a result, the area to be pressed is increased and the pressure per unit area is reduced, which is extremely advantageous in that it can alleviate wear and tear on the area and eliminate inconveniences such as poor detachment.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a tip-knot type sharpening pencil using a chuck body, Fig. 2 is an exploded perspective view of the chuck body shown in Fig. 1, and Figs. 3 and 4 are other embodiments of the chuck body. Exploded perspective view showing 5-
Figure A is a cross-sectional view of a main part showing an embodiment different from the present invention, which is adopted to apply a tightening force toward the center at the proximal end of the chuck component, and Figures 5-B to 5-D are sectional views of the main parts of the chuck. - FIG. 4 is a sectional view showing different embodiments of the present invention corresponding to FIG. 1... Chuck body, 2... Chuck component piece, 2
a... Core holding part, 2b... Intermediate arm part, 2c... Base end part, 3... Rocking fulcrum, 5... Ball receiver, 8...
...Spring, 9...Ball.

Claims (1)

[Claims] 1. A base end that receives the spring that urges backward and receives the thrust given by the knocking action of the sharp pencil, and a center-directed force obtained by converting the axial force of the spring. The chuck consists of a plurality of chuck components, each consisting of a core holding part that is tightened and has a ball seat on the outer surface thereof, and an intermediate arm part that connects both parts. A sharp pencil with a mating structure that can swing around a swinging fulcrum formed on the opposite end surface, and the base end behind the swinging fulcrum is a conversion part that converts the thrust force into a tightening force directed toward the center. A chuck for a sharp pencil, characterized in that the converting portion of the base end portion is a large diameter portion that cooperates with the outer cylinder of the ball chuck, or an inclined large diameter portion that cooperates with the spring. body.