KNOCK-ACTION MECHANICAL PENCIL

Abstract: Knock-action mechanical pencil comprising a lead-forwarding mechanism (2) and an outer sleeve (1), said lead-forwarding mechanism being inserted from the rear end of said outer sleeve. An elastic member (5) for prevention of looseness is inserted between a chuck ring sleeve (3) which constitutes said lead-forwarding machanism and an inner ring (4) for prevention of forward movement which is provided on the inside of the outer sleeve. A retaining sleeve (10) having a slit (9) extending over the full length is inserted between a mouth part (7) and a radially outward projecting step-shaped part (8) behind the mouth part, of a forward member (6) which is connected to the chuck ring sleeve. A retaining part (11) which is provided at the forward end portion of the retaining sleeve is set between the mouth part of the forward member and the forward end of the outer sleeve.

Description: Background of the Invention This invention relates to a knock-action mechanical pencil in which a lead-forwarding mecanism is attached to an outer sleeve by an inner ring for prevention of forward movement, an elastic member for prevention of looseness which serves to press backward the lead-forwarding mechanism to said inner ring and a retaining sleeve for prevention of backward movement of a mouth part. As such a usual knock-action machanical pencil, there is known, for example, that descrived in Japanese Utility Model Laying-Open No. 87984/59(1984). In this usual example, an inner sleeve which costitutes a lead-forwarding mecanism is inserted in an outer sleeve under the condition that the inner sleeve is pressed backward by a retaining ring which is set in small groove engraved over all the circumference of an end of a mouth piece in the inner sleeve and an elastic member which is put on the connecting part of the inner sleeve and which presses against a receiving part for the elastic member. That is, the above example solves problem that in the usual screwing mouth piece-typed pencil, the mouth piece becomes loose at the time of making use of the pencil so that lead snaps and also the mouth piece sometimes slips out and is lost by attaching the lead-forwarding mechanism to the outer sleeve by the retaining ring and the elastic member. However, the usual example has problems that in the above example, an assembly of pencil necessitates an action for maintaining the state that the inner sleeve is forced backward and an action for inserting the retaining ring by means of jig, and therefore it cannot be done in one motion, because the lead-forwarding mechanism is attached to the outer sleeve by engaging the retaining ring with the small groove engraved over all the circumference of an end of the mouth piece, and that looseness between the small groove and the retaining ring can not be not compensated without heightening the working accuracy of both the small groove and the retaining ring while there is the possibility of that the retaining ring slips out from the small groove due to an elasticity of the elastic member and jig is necessitated for setting of the retaining ring. Brief Summary of the Invention This invetion intends to provide a knock-typed pencil in which the snap of lead and slipping out due to looseness of the mouth piece are prevented, attachment of the lead-forwarding mechanism to the outer sleeve can be easily, positively and without looseness done without using jig, and without heightening the warking accuracy, and also the construction is simple and can be cheaply made. That is, knock-action mechanical pencil according to this invention as shown in the drawings comprises a lead-forwarding mechanism 2 inserted from the rear end of an outer sleeve 1, and is characterized in that an elastic member 5 for prevention of looseness is inserted between a chuck ring sleeve 3 which constitutes said lead-forwarding mechanism 2 and an inner ring 4 for prevention of forward movement of said elastic member 5 and which is provided on the inside of the outer sleeve 1, a retaining sleeve 10 for attaching said mechanism 2 to said outer sleeve 1 and having a slit 9 extending over its full length is inserted between a mouth part 7 and a radially outward projecting step-shaped part 8 behind the mouth part of a forward member 6 which is connected to the chuck ring sleeve 3, and that a retaining part 11 which is provided at the forward end portion of the retaining sleeve 10 is set between the mouth part 7 of the forward member 6 and the forward end of the outer sleeve 1. The lead-forwarding mechanism 2 is thrust from the rear end of the the outer sleeve 1 against the elastic member 5 for prevention of looseness which is inserted between the chuck ring sleeve 3 and the inner ring 4 for prevention of forward movement being provided on the inside of the outer sleeve 1 so that the rear end of the retaining sleeve 10, which is inserted between the mouth part 7 and the radially outward projecting step-shaped part 8 behind the mouth part, of a forward member 6 which is connected to the chuck ring sleeve 3, is pushed by the radially outward projecting step-shaped part 8. When the the retaining part 11 being provided at the forward end of the retaining sleeve 10 is projected out from the forward end of the outer sleeve 1, the pushing operation is stopped. Then, by slightly pulling backward the lead tank 13, the retaining part 11 is set between the mouth part 7 of the forward member 6 and the forward end of the outer sleeve 1 by which the lead-forwarding mechanism 2 can be attached to the outer sleeve 1. Brief description of the drawings In the drawings: Fig. 1 is a cross-sectional view of the essential part of an example of knock-action mecanical pencil according to this invention. Fig. 2 is a cross-sectional view of the essential part of the example shown in Fig. 1, but showing the state when a lead-forwarding mechanism is attached to the outer sleeve. Figs, 3(a) and (b) are a perspective view showing an illustration of a retaining sleeve which is applied to this example, and a perspective view showing the state before the retaining sleeve is formed perspectively. Figs. 4(a) and (b), and Figs. 5(a) and (b) are perspective views showing the other illutrations of the retaining sleeves and perspective views showing the states before the retaining sleeves are formed. Figs. 6(a) and (b) are a cross-sectional view and a perspective view taken on line VI-VI showing the further other illustration of the retaining sleeve. Figs. 7(a) and (b) are a cross-sectional view and a perspective view taken on line VII-VII. Fig. 8 is a cross-sectional view of the essential part of another example. Fig. 9 is a cross-sectional view of the essential part of the example shown in Fig. 8, but showing the state when the lead-forwarding mechanism is attached to the outer sleeve; and Fig. 10 is a partially sectional view showing the state when the retaining sleeve of Fig. 5 is used. 5. Detailed Description Then, referring to drawings, an example accordings to this invention is illustrated. Fig. 1 is a cross-sectional view of the essential part of an example of a knock-action mechanical pencil according to this invention, Fig. 2 is a cross-sectioal view of the essential part of the example shown in Fig. 1, but showing the state when a lead-forwarding mechanism is set, Figs. 3 (a) and (b) are a perspective view showing an illustration of a retaining sleeve which is applied to this example, and a perspective view showing the state before the retaining sleeve is formed, respectively. In Fig. 1, numeral 1 designates an outer sleeve, 1a a forward part of the outer sleeve and a lead-forwarding mechanism 2 which is inserted from the rear end of the outer sleeve 1. The lead-forwarding mechanism 2 comprises a lead tank 13, a chuck 14 which is connected to the lead tank 13, a chuck ring 15 which is put on the chuck 14, the chuck ring sleeve 3 being contacted with the rear end of the chuck 15, a chuck spring 16 which is provided between the chuck ring sleeve 3 and the forward end of the lead tank 13, the forward member 6 which is connected to the chuck ring sleeve 3 by means of screw and the like, and the mouth part 7 of the forward member 6. Numeral 17 designates a supporting part of a lead 18, such as rubber packing which is provided on the inner side of the mouth part 7. The spring 5 for prevention of looseness ( an elastic member ) is inserted between the chuck ring sleeve 3 wchich constitutes the above lead-forwarding mechanism 2 and an inner ring 4 for prevention of forward movement which is provided on the inside of the forward end portion of the outer sleeve 1 by means of fixing and the like or integrally. A retaining sleeve 10 ( refer Fig. 3(a) ) having a slit 9 extending over the full length is set between the mouth part 7 and the radially outward projecting step-shaped part 8 behind the mouth part 7 of the forward member 6. In this example, the retaining sleeve 10 may have the desired number of slits 9a extending halfway. A retaining part 11 which is provided at the forward end portion of the retaining sleeve 10 is inserted between a shoulder part 12 of the forward member 6 and the forward end portion of the outer sleeve 1 . The retaining part 11 is that which is projected out from the forward end of the retaining sleeve 10 in the form of an arc ( refer Figs. 1 to 3 ), that which is projected out from the portion withdrawing at short distance from the forward end of the retaining sleeve 10, in the same manner ( refer Fig. 4(a) ), that which is formed by providing raised flaps in the forward end portion of the retaining sleeve 10 ( refer Fig. 5 (a) ), that which is formed by the forward end portion of the retaining sleeve 10 ( refer Fig. 6 (a) ), and that which is formed by providing a hook- shaped projecting part at the forward end portion of the retaining sleeve 10 ( refer Fig. 7(a) ). The retaining sleeve 10 can be formed by rolling up a plate-shaped body provided with the retaining part 1. Further the retaining sleeve 10 may be a tubular body having slits 9, 9a and the retaining part 11. In this examle having the above construction according to this invention in order to attach the lead-forwarding mechanism 2 to the outer sleeve 1, the lead-forwarding mechanism is thrust from the rear end of the outer sleeve 1 against the spring 5 for prevention of looseness which is inserted between the chuck ring sleeve 3 and the inner ring 4 for prevention of forward movement being provided on the inside of the outer sleeve 1 so that the rear end of the retaining sleeve 10, which is inserted between the mouth part 7 and the radially outward projecting step-shaped part 8 behind the mouth part, of the forward meber 6 which is connected to the chuck ring sleeve 3, is pushed by the radially outward projecting step-shaped part 8, as shown in Fig. 2. When the retaining part 11 being provided at the forward end of the retaining sleeve 10 is projected out from the forward end of the outer sleeve 1, the pushing operation is stopped. Then, by slightly pulling backward the lead tank 13, the retaining part 11 is set between the shoulder part 12 of the mouth part 7 of the forward member and the forward end of the outer sleeve 1 by which the lead-forwarding mechanism 2 can be attached to the outer sleeve 1. Further, the lead-forwarding mechanism 2 can be taken out with the spring 5 for prevention of looseness, by bending inward the retaining part 11 of the retaining sleeve 10 under the condition that the lead-forwarding mechanism 2 has been pushed in(refer Fig. 2). According to this example, the lead-forwarding mechanism 2 can be attached to the outer sleeve 1 only by pushing and releasing the chuck ring sleeve 3 against the spring 5 for prevention of looseness and by inserting the retaining part 11 of the retaining sleeve 10 having slit extending over the full length which is set between the mouth part 7 and the radially outward projecting step-shaped part 8 between the shoulder part 12 of the mouth part 7 of the forwarding member 6 and the forward end of the outer sleeve 1. Therefore, the attachment of the lead-forwarding mechanism 2 can be done by an action of only pushing and releasing the lead-forwarding mechanism. Looseness can be easily removed by inserting the retaining part 11 of the retaining sleeve 10 between the shoulder part 12 of the mouth part 7 and the forward end of the outer sleeve 1. Besides, there is no possibility that the lead-forwarding mechanism slips out from the outer sleeve 1. Further, as the retaining sleeve 10 is inserted from the mouth part 7 side by utilising the slit 9 extending over the full length before the lead-forwarding mechanicm 2 is set in the outer sleeve 1, jig is not necessitated. In addition, it is of course possible to prevent the snap of lead 18 and the slipping out due to looseness of the mouth part 7. Fig. 8 is a cross-sectional view of the essential view of another example, Fig. 9 is a cross-sectional view of the essential view of another example shown in Fig. 8, but showing the state when a lead-forwarding mechanism is attached to the outer sleeve. In this example, there is shown an illustration in which the retaining sleeve 10 is set between the mouth part and the radially outward projecting step-shaped part 8. In this case, bending of the retaining sleeve 10 can be more easily done, because the whole retaining sleeve 10 can be bent. However, in the example shown in Fig. 1, bending of the retaining sleeve 10 is a little inferior to the example shown in Fig. 8, as the retaining sleeve 10 is bent on the rear end of the retaining sleeve 10 as the supporting point in the Fig. 2. That is, according to this invention, it is possible to easily attach the lead-forwarding mechanism to the outer sleeve 1 in one action. In addition, jig is not necessitated for attachment of the retaining sleeve 10. there is no possibility that the lead forwarding mechanism slips out from the outer sleeve.

Claims: Knock-action mechanical pencil comprising a lead-forwarding mechanism (2) and an outer sleeve (1), the lead-forwarding mechanism (2) being inserted from the rear end of the outer sleeve (1), characterized in that an elastic member (5) for prevention of looseness is inserted between a chuck ring sleeve (3) which constitutes said lead-forwarding machanism (2) and an inner ring (4) for prevention of forward movement of said elastic member (5) and which is provided on the inside of the outer sleeve (1), a retaining sleeve (10) for attaching said mechanism (2) to said outer sleeve (1) and having a slit (9) extending over its full length is inserted between a mouth part (7) and a radially outward projecting step-shaped part (8) behind the mouth part of a forward member (6) which is connected to the chuck ring sleeve (3), and that a retaining part (11) which is provided at the forward end portion of the retaining sleeve (10) is set between the mouth part (7) of the forward member (6) and the forward end of the outer sleeve (1). Knock-action mechanical pencil as claimed in claim 1 characterized in that the retaining sleeve (10) is formed by rolling up a plate-shaped body. Knock-action mechanical pencil as claimed in any of claims 1 and 2 characterized in that the retaining sleeve(10)has an another slit (9a) extending halfway besides the slit (9) extending over the full length. Knock-action mechanical pencil as claimed in any of claims 1 to 3 characterized in that the retaining part (11) of the retaining sleeve (10) is a projecting part which outward projects.

Inventors: EBINUMA, TADAYOSHI, KAGEYAMA, SHUHEI, MITSUYA, YOSHIHIDE
Applicants: KOTOBUKI & CO., LTD.
Application year: 1988
Main classification: B43K21
IPC codes: B43K21