US2700959A - Mechanical pencil - Google Patents

Description

R. EINSELE MECHANICAL PENCIL Filed Nov. 29, 1951 I ||||I| Il Feb. 1, 1955 ROBERT lA/SELF United States Patent() MECHANICAL PENCIL Robert Einsele, Pforzheim, Germany, assignor to Rodi 8a Wienenberger A.G., Pforzheim, Germany, a firm Application November 29, 1951, Serial No. 258,828

Claims priority, application Germany August 20, 1951 8 Ciaims. (Cl. 1Z0- 17) T he present invention relates to mechanical or refill able pencils and is particularly directed to a pencil of this type in which the opening and closing of the clamping tongs, by means of which the leads are fed forward and clampingly secured in position, is eifected with the aid of a sleeve-like clamping member which is shiftably arranged for longitudinal displacement between two stops limiting the forward and backward movement of the clamping member.

'in order that the lead is iirmly and non-yieldingly supported in the lead holder during writing, it has already been proposed to arrange the clamping and feeding tongs as near to the pointed writing end of the lead holder as possible. However, in an arrangement like that the conical front part of the holder has to enclose not only the clamping tongs but also the clamping member for the clamping tongs and the front stop for the clamping member, so that considerable space is required for an arrangement of this kind which makes it impossible to give the pointed front end of the holder the much desired slender shape.

It has been tried to reduce the diameter of the hollow interior of the conical front part by screwing an exteriorly threaded extension of the conical front part into an interiorly threaded extension of the outer casing and by using the rear end of the threaded extension of the conical front part simultaneously as front stop for the clamping member. This, however, has the drawback that the length of the stroke of the clamping member is not definitely determined and that it may either be too short or too long.

It has further been found that in constructions of this last mentioned type, in which the clamping tongs are farther removed from the writing end of the pencil, the leads are not iirmly supported and retained in the pencil, so that they will easily turn in the holder when worn off or drop out of the holder when worn down to short bits regardless of whether the pencil is provided with a slitted or non-slitted writing point.

Another drawback of the known constructions is due to the fact that the very moment the clamping tongs are not embracing a lead (which may occur when the magazine is empty or when the pencil is turned upside down) the clamping jaws of the clamping tongs recede in inward direction, so that the guide tube for the leads and the clamping tongs fastened to it can then be withdrawn from the casing without difficulty or may even drop out of the casing by means of their own weight.

All of these drawbacks are overcome by the construction disclosed in the present invention which is so devised that a cylindrical sleeve serving as guide channel for the clamping member of the clamping tongs is provided at its forward end with an inwardly projecting shoulder serving as a stop for the forward movement of the clamping member, and at its rear end with a cylindrical eX- tension having its forward end connected to the rear end of that cylindrical sleeve in such a way that a stop is formed for the backward movement of the clamping member. The rear end of the cylindrical extension is inwardly bent and embraces the guide tube for the leads which at its forward end carries the clamping tongs, the guide tube being provided with a circumferential projec tion cooperating with the inwardly bent rear end of the cylindrical extension to stop the backward movement of the guide tube.

It will be seen that in a construction like this it is no longer possible for the guide tube and the clamping tongs ICC to drop out of the casing or to be withdrawn from it when the clamping tongs are not embracing a lead.

The invention is further characterized by the provision of an additional clamping member for the leads provided with a conically shaped and resilieutly designed rear end. This additional clamping member is arranged in the conical front part of the pencil directly forwardly of the front end of the clamping tongs. The additional clamping member may be shiftably arranged in the conical front part and be provided at its forward end with braking tongs for the lead in such a way that the braking tongs slightly project from the writing end of the pencil and, in cooperation with a compression spring and the aforesaid conical rear end of the additional clamping member, tend to close, so that they are constantly exerting a clamp ing or braking pressure upon the lead embraced by them.

Through the provision in the conical front end of the pencil of additional clamping or braking tongs which do not serve for advancing the lead in the holder but merely for securing the lead in the holder in firmly supported and non-yielding position, the dropping out of short bits of lead or the turning of worn off leads is reliably prevented.

Additional features and advantages of the invention will be understood from the following detailed descrip tion, taken in connection with the accompanying drawings, forming a part of this application and in which 1 have illustrated by way of example an embodiment of my invention. However, my invention is not confined to the embodiments shown in the drawings, but may be changed or modified, so long as such changes or modiiications mark no material departure from the essential features of the invention as expressed in the appended claims.

In the drawings in which like parts are referred to by the same reference numerals:

Fig. 1 is a central longitudinal section of the mechanicl pencil showing the lead feeding means in their position o rest;

Fig. 2 is a central longitudinal section of the mechani cal pencil showing how the lead is fed forward by the feeding means through pressure exerted upon the push cap at the rear end of the pencil.

Referring now to the drawings in detail, the reference numeral 1 denotes the outer casing of the mechanical pencil consisting either of metal or of synthetic plastic material as illustrated in the drawings. Arranged in the outer casing 1 is an inner casing 2 of metal which is provided at its rear end with an exteriorly threaded portion adapted for engagement in an interiorly threaded annular member 3, an annular outer shoulder of which rests against the rear end of the outer casing 1 and thus serves as a closure member for the latter. Inserted into the forward end of the inner casing 2 is a cylindrical sleeve 4 provided with a threaded front portion 5 onto which the conical front part 6 of the lead holder is screwed. By means of the annular shoulder 7 of the conical front part 6 and the annular shoulder of the closure member 3 the inner casing 2 and the feed mechanism enclosed by the latter are secured in the outer casing 1. The annular closure member 3 also serves as a means to secure the clip 3 in its position. At the place where the portion of smaller diameter of the inner casing 2 merges into the portion of larger diameter of the inner casing 2 there is a slight clearance between the shoulder portion 9 of the inner casing and the shoulder portion 10 of the outer casing to take care of slight variations in manufacture of the outer casing 1 when the latter consists of plastic material. If the outer casing is produced from metal the provision of a clearance between the two shoulder portions is not necessary.

Positioned in the rear portion of the inner casing 2 is the magazine 11 for the leads, whose rear end is closed up by the removable push cap 12 which, when it is pushed onto the rear end, projects with its forward end into the annular closure member 3. Screwed into the front end of the magazine is the guide tube 13 for the leads provided at its forward end with the clamping tongs 16 which in cooperation with the clamping member 14 effects the forward feeding of the leads 15.

The feed path of the clamping member 14 is at one end terminated by the inwardly projecting shoulder 17 at the forward end of the bore 18 in the sleeve 4, and at the other end by the stop member 19 for the clamping member 14. The stop member 19 is of cylindrical shape and secured at its forward end to the rear end of the sleeve 4 through flanging. The stop member 19 surrounds a portion of the guide tube 13 and prevents by means of its inwardly bent shoulder-portion 21 in cooperation with a ring 20 fastened on the guide tube 13 the withdrawal in backward direction of the magazine 11 with guide tube 13 and clamping tongs 16 when the clamping tongs 16 no longer embrace a lead 15. The inwardly bent shoulder portion 21 is of conical shape, so that when the ring 20 is engaged by it, the ring 20 and the guide tube 13 are clampingly secured in the position of Fig. l. The compression spring 22 bears at one end against the shoulder portion 21 of the stop member 19 and at its other end against the bottom of the magazine 11.

The guide tube 13, which carries at its forward end the clamping tongs 16, engages in the enlarged boreportion 23 in the rear end of the clamping member 14 and displaces the latter in forward direction when hitting against the annular shoulder 24 of the clamping member 14.

Positioned in the conical front part 6, which is screwed onto the threaded portion of the sleeve 4, and shiftably supported in the sleeve 26 is an additional clamping member 25. The additional clamping member 2S is conically and resiliently designed at its rear end and carries at its front end the braking tongs 27 which somewhat project from the conical part 6 and merely serve as a means to secure the lead in its working position and to prevent short or worn down pieces of lead from dropping out of the holder.

In order to make sure that the additional clamping member will not slip out of the rear end of the conical part 6, when the latter is not screwed onto the threaded portion 5 and when the braking tongs 27 are not ernbracing a lead 15, the clamping member 25 is provided with a projecting portion 28 which in cooperation with the sleeve 26 prevents the clamping member 25 from dropping out of the conical part 6. The compression spring 29 by means of which the braking tongs 27 are always secured in closing position is at one end bearing against the annular shoulder of the bore 31 and at its other end against the annular shoulder 32 surrounding the place where the rear end of the braking tongs 27 is fastened in the front end of the clamping member 25.

In order that during the forward feeding of the leads the braking tongs 27 be slightly opened up, the clamping tongs 16 are so arranged at the guide tube 13 that the clamping tongs shortly before reaching their foremost position will hit against the conical rear end of the additional clamping member 25 displacing thereby the clamping member 25 and the braking tongs 27 carried by the latter against the pressure of the spring 29 in forward direction, as illustrated in Fig. 2. It will be noticed that the clamping tongs 16 have been provided for this purpose with dat front ends instead of the conical front ends employed hitherto.

This displacement in forward direction of the additional clamping member 25 automatically results in slight opening up of the braking tongs 27 which, as has already been mentioned, merely serve the purpose of securing the lead 15 in its working position. It may, however, be said that this forcible displacement in forward direction is not needed during normal operation, as the forward feeding of the lead 15, because of the frictional contact between the lead and the clamping member 25 and braking tongs 27, automatically results in slight displacement in forward direction of the additional clamping member 25 and braking tongs 27.

The mechanical pencil according to the present invention operates in the following manner:

When the guide tube 13 is pushed in forward direction, the clamping tongs 16, which are clamped to the clamping member 14 in the position shown in Fig. l, move forwardly together with the clamping member 16 and take along the lead 15. When the clamping member 14 strikes the shoulder 5 of the sleeve 4, it is stopped while the clamping tongs continue the forward movement into the position shown in Fig. 2. During such movement the clamping tongs 16 are released by the clamping member 14 and resiliently spread to release the lead 15. At the end of the forward movement the dat front face of the clamping tongs 16 engages the resilient rear end of the additional clamping member 25, whereby tongs 27 are pushed out of the cap 6. Since the clamping tongs 27 spread slightly, the lead can be manually adjusted in this position. When the cap 12 is now released, the spring 22 retracts the clamping tongs 16 and the guide tube 13. During the first part of the backward movement, the member 25 is released, and the clamping tongs 27 clamp the lead again so that it cannot be taken along in rearward direction by the friction of the clamping tongs 16 which otherwise may happen although the clamping tongs 15 are still in open and spread position. During further rearward movement, the outer conical face of the clamping tongs 16 engages the inner conical face of the clamping member 14 so that the lead is again gripped by the clamping tongs 16. During last part of the rearward movement, the clamping member 14 moves together with the tongs 15 until the rear face of member 14 strikes the shoulder formed by the front end of the stop member 19. Due to the small friction between the clamping member 14 and the inner face of the sleeve 4, the clamping tongs are not tightly pressed against the inner face of the clamping member 14 but slide on the lead until member 14 is stopped by member 19. Then spring 22 presses the clamping tongs 16 into the clamping member 14 until the annular projecting member 20 engages the conical inner shoulder 21 of the stop member 19. The conical shoulder 21 clamps the annular member 20 and thereby holds the guide tube 13 in its rearward end position so that slight manual pressure is required for moving the guide to out of the position shown in Fig. l.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. In a mechanical pencil of the type in which the forward feeding of the leads is effected through pressure exerted upon a push-cap, an outer casing; a magazine for pencil leads provided with a push-cap shiftably arranged in the rear end of said outer casing; a springloaded guide tube for the pencil leads secured at its rear end to the bottom of said shiftable magazine; a pair of clamping tongs mounted on the forward end of said guide tube; a cylindrical sleeve rigidly secured in the forward end of said outer casing and surrounding said clamping tongs in spaced relation thereto, said cylindrical sleeve being provided at its forward end with an inwardly projecting annular shoulder; a clamping member of sleevelike formation shiftably arranged between said cylindrical sleeve and said clamping tongs for guidance in said cylindrical sleeve, said clamping member being adapted to control the opening and closing movement of said clamping tongs in cooperation with said push-cap, springloaded guide tube and cylindrical sleeve and having its forward movement limited by said inwardly projecting annular shoulder of said cylindrical sleeve; a stop-member of cylindrical formation surrounding a portion of said spring-loaded guide tube in spaced relation thereto and having its forward end secured t0 the rear end of said cylindrical sleeve in such a way that thereby at the rear end of said cylindrical sleeve an inwardly proiecting shoulder is formed adapted to serve as a stop for the backward movement of said clamping member, and having an inwardly bent conical rear end surrounding said guide tube between the rear end of said cylindrical sleeve and said magazine; an annular projection fixed to said guide tube between the rear end of said cylindrical sleeve and said inwardly bent rear end of said cylindrical stop- -iemben said annular projection being clamped in said inwardly bent conical rear end of said cylindrical stopmember during the backward movement of said springloaded guide tube and said magazine and serving as a stop means; and a hollow pointed front part for said mechanical pencil detachably mounted on the front end of said outer casing and provided at its forward end with an opening for the leads fed forward by said clamping tongs to pass through.

2. A mechanical pencil as specified by claim l, in which said clamping member of sleeve-like formation is provided in its rear end with an enlarged bore portion, and in which the forward end of said guide-tube for the leads on which said clamping tongs are mounted engages in said enlarged bore portion of said clamping member.

A mechanical pencil as specified by claim l, in which said clamping tongs mounted on the front end of aid guide-tube for the leads are provided with dat frontaces.

4. A mechanical pencil as specified by claim 1, in which said cylindrical sleeve secured in the forward end of said outer casing is provided at its forward end with an extension, and in which said hollow pointed front part is detachably mounted on said extension of said cylindrical sleeve.

5. In a mechanical pencil of the type in which the forward feeding of the leads is effected through pressure exerted upon a push-cap, an outer casing; a magazine for pencil leads provided with a push-cap shiftably arranged in the rear end of said outer casing; a spring-loaded guide tube for the pencil leads secured at its rear end to the bottom of said shiftable magazine; a pair of clamping tongs mounted on the forward end of said guide tube; a cylindrical sleeve rigidly secured in the forward end of said outer casing and surrounding said clamping tongs in spaced relation thereto, said cylindrical sleeve being provided at its forward end with an inwardly projecting annular shoulder; a clamping member of sleeve-like formation shiftably arranged between said cylindrical sleeve and said clamping tongs for guidance in said cylindrical sleeve, said clamping member being adapted to control the opening and closing movement of said clamping tongs in cooperation with said push-cap, spring-loaded guide tube and cylindrical sleeve and having its forward movement limited by said inwardly projecting annular shoulder of said cylindrical sleeve; a stop-member of cylindrical formation surrounding a portion of said springloaded guide tube in spaced relation thereto and having its forward end secured to the rear end of said cylindrical sleeve in such a way that thereby at the rear end of said cylindrical sleeve an inwardly projecting shoulder is formed adapted to serve as a stop for the backward move ment of said clamping member, and having an inwardly bent conical rear end surrounding said guide tube between the rear end of said cylindrical sleeve and said magazine; an annular projection Xed to said guide tube between the rear end of said cylindrical sleeve and said inwardly bent rear end of said cylindrical stop-member, said annular projection being clamped in said inwardly bent conical rear end of said cylindrical stop-member during the backward movement of said spring-loaded guide tube and said magazine and serving as a stop means; a hollow pointed front part for said mechanical pencil detachably mounted on the front end of said outer casing and provided at its forward end with an opening for the leads fed forward by said clamping tongs to pass through; and an additional clamping member for the leads arranged in the hollow interior of said pointed front part and provided with a conical funnel-shaped resilient lead guiding rear end extending into close proximity of the forward end of said clamping tongs said additional clamping member being engaged by said clamping tongs during forward movement of said clamping tongs and operated by the same.

6. A mechanical pencil as specified by claim 5, and a spring-loaded pair of braking tongs secured at their rear end to the front end of said :additional clamping member and so dimensioned that their forward end slightly projects from said opening in the forward end of said pointed front part, said braking tongs constantly tending to close.

7. A mechanical pencil as specified by claim 5, and a spring-loaded pair of braking tongs secured at their rear end to the front end of said additional clamping member and so dimensioned that their forward end slightly projects from said opening in. the forward end of said pointed front part, said spring loaded braking tongs and said clamping tongs and said conical rear end of said additional clamping member being so devised and arranged for cooperation with each other that during the forward feeding of the leads the front end of said clamping tongs slightly hits against the conical rear end of said additional clamping member and thereby slightly displaces said braking tongs in forward direction against the spring pressure.

8. A mechanical pencil as specified by claim 5, including braking tongs including a spring and secured to its forward end and so dimensioned that their forward ends slightly project from said opening in the forward end of said pointed front part, and an annular stop-member abutting on its circumference against the forward end of said cylindrical guiding sleeve to thereby limit the backward movement of said shiftable additional clamping member in its rearmost position against the pressure of said spring, said spring bearing at one end against the inner wall of said hollow pointed front part and at its other end against the forward end of said shiftable additional clamping member.

References Cited in the file of this patent UNITED STATES PATENTS 1,898,598 Rosenthal Feb. 21, 1933 2,049,965 Leistenschneider Aug. 4, 1936 FOREIGN PATENTS 36,508 France Mar. 4, 1930 (Addition to No. 638,536) 176,959 Switzerland July 16, 1935 274,269 Switzerland June 16, 1951

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