US2108441A - Pencil - Google Patents

Description

H. MAUCHER Feb. 15, 193s.

PENCIL Filed Sept. 29, 1956 2 She`ets-Sheet l y INVENTOR, Hams Malw/r,

ATTORNEY.

Feb. 15, 1938. H MAUCHER I 2,108,441

PENCIL Filed Sept. 2.9, 1936 2 Sheets-Sheet 2 r INVENTOR, H11/ns Mancha;

4 ATTORNEY.

Patented Feb. 15, 1938 UNITED STATES PATENT OFFICE PENCIL Hans Mancher, New York, N. Y.

Application September Z9, 1936, Serial No. 103,071

4 Claims.

This invention relates in general to pencils of the mechanical type. Pencils, of'this type are adapted for carrying leads which are insertible therein or removabletherefrom and the life of such a pencil is therefore not dependent on the life of the lead, but merely dependent on the life of its mechanical parts. When inserted into a pencil the leads are adapted to havethe ends thereof protruded from the pencil into a position of use, and appropriate mechanism for elfecting this function is provided in the pencil. l

From one aspect my invention relates'not to mechanical pencils asa Whole, but to specific mechanism for protruding the leads from holders therefor provided inthe pencil.

In the particular embodiment of my invention disclosed in this application my invention has been shown as applied to a pencil of the magazine type having a plurality of lead holders, any one of which may be selectively projected, but it is to be understood that my invention is not in- 'tended to be' limited in its applicationA to the specific embodiment thereof herein disclosed, in which the pencil is provided with a plurality of lead holders.

The general objects of my inventionmay be stated to be the provision of a mechanical pencil having therein a simple and effective mechanism adapted for projecting lead out Aof a holder therefor, and secondly the provision of effective mechanism for 'projecting the lead from the lead holder of such a pencil. The iirst of these objects involves simplicity of design whereby the manufacturing costs may be reduced, and further compactness, so that if a plurality of lead holdersfaie used in one pencil, they may be accommodated in a casing of ordinary size. The second, as well as the first object, involves a construction providing for adequate strength of all of the parts and their reliability in operation, and one in which the lead will be caused to advance by the application of a small force, and yet with sumcient speed.` yFor the attainment of these objects and such .other objects as will appear or be pointed out hereinafter, I have illustrated one embodiment of my'invention in the accompanying drawings, in which:- `ltigure 1 is an elevational viewv of a magazine pencil having my inventionr'applied thereto, one

itsiprotruded or operative position;

Figure 1a is a constructional detail of the4 pencil of Figure 1:

Figure 21s a sectional view taken substantially` Figure 3;

Figure 6 is a side elevationalview, taken at right angles to the showing of Figure 3, of portions of the assembly of Figure 3; and

Figure 7 is a view similar to Figure 3, of a portion of a modified form of lead holder.

Before entering into a description of the details of my invention, I will premise that it is applicable to mechanical pencils in general, and not only to the particular form thereof, disclosed herein. For instance, the assembly of Figure 3, instead of being a part of a multi-lead pencil, might be usedby itself as a pencil, either just as shown, or with the addition of an outer casing so as to enhance its appearance, and it will be obvious that when so used portions thereof shown in the drawings might be omitted.

However, I have herein disclosed the application of my invention to amulti-lead pencil similar in many respects to the one disclosed in the U. S. Patent 1,889,550 to Hirth of November 29, 1932. Such pencils being well-known, it will be unnecessary to' describe the broad features of such a magazine pencil in great detail, and only a brief reference thereof will be made, while the construction of the lead holders will be described in full detail.

Referring now to theI drawings Vin detail, it will be found that the main features of .a multilead magazine pencil are indicated in Figures 1 -and 2, and it will be observed that the pencil is there'shown as comprising atubular casing l0 having a conical tip Il with an opening I3 therein,`said opening being located at the apex of said conical tip. The casing is shown as having slots l2 in the sides thereof, of which four are indicated by way of example, although obviously there is no limitation as to the particular mem- K ber. Slidable within the slots l2 are members I4 offthe lead holders of the pencil being shown in providedwith enlarged heads l5 positioned extfernally of the casing, whereby said member I4 vmay be manipulated, said heads also serving to keep the members I4 within the slots. Each member i4 is mounted on a spring i6, shown as flattened and provided with an angularly bent portion 2| at one end while at its other end each of the springs I6 is shown as attached to a lead carrier denoted as a whole by A. Four of these lead carriers A are shown, one corresponding to each of the aforementioned slots I2.

On referring to Figure 1 it will be observed that one of the lead carriers A is shown as in its position of use, in which its lower end projects outwardly through the opening I3 of the casing III, whereas the other lead carriers A are in retracted position (as indicated by the position of the members I5 in Figures 1 and 2). Owing to the restricted size of opening. I3 only one lead holder can pass therethrough at one time.

The eii'ect oi.' projecting one of the lead holders A'is to compress a coil spring I1 positioned withjyli'zi-'a' bushing I9, slidably mounted within the casf ing'ill, this being effected by the engagement of the aforementioned ang'ularly bent portion 2| of the spring- |6 with the upper end of the bushing I9, while on the other hand the spring is kept from moving downward by the tapered portion I| of the casing Ill, which is not of sufficient diameter to accommodate it. The coil spring I1 while under compression tends to push kthe projectingholder A upward, and to prevent upward movement of the holder some means, such as the undercut shoulder indicated in dotted lines in Figure 1 at 23, may be used. When the member I4 is brought opposite this shoulder and is then moved sideways into the lateral recess of the slot I2 at this point, it will engage the shoulder 23 and will be kept there by the pressure of spring I1.

In order to facilitate the operation of bringing the member I4 into engagement with the shoulder 23 and make it automatic, the lower end of the slot I2 may be formed on an incline as shown at 3| in Figure la. Byreferring to said figure it will be observed that four positions of the member I4 are indicatedtherein, three of them a, b and c being indicated in dotted lines and illustrating successive positions of the member I4 as it is pushed downwardly alongi the slot I2 and against the inclined wall 3|, While the fourth position indicated at d represents the final locked position with the part I4 in contact with the shoulder 23. It will be observed that in the b position, and with pressure applied as indicated by the arrow, so as to cause the member I4 to move downwardly in the slot I2 the effect of the inclinedwall 3| will be to guide the member I4 laterally into the position c. Thereafter, on releasing the member I4, it will move upwardly, due to the action of spring I1, so as to engage the shoulder 23, where, due to the undercut of the shoulder and the action of said spring, as already explained, it will be held.

It will be further observed that spring |1 tends normally to keep all holders A in retracted position. When it is compressed by projecting one of the holders, it no longer acts on the other holders A, and to retain these in position use may be made of the resiliency of the spring I6, which is shown as so arranged that, due to the engagement of the head I5 with the outer walls of casing I0 and the engagement of the spring extension I6 .with the inner walls of a tapered member 25 set into casing I0 at its upper end, the spring is under tension suflicient to retain the holder A in place.

On. referring to Figures 3, 4, 5 and 6 the details` of the lead carrier construction will become apparent. It will be observed that, as

shown therein, the main elements of this assembly are an inner sleeve 26, and an outer sleeve k24, the latter being connected at one end to the aforementioned spring I6 carrying the member I4. The inner sleeve is nested within the outer sleeve so that the inner sleeve may turn within the outer sleeve, and the inner sleeve is provided with an annular groove 28 adapted to be engaged by a complementary flange 28 formed on the interior wall of the outer sleeve. This flange may be formed by crimping the outer sleeve in place on the inner sleeve, after assembly thereof, by depressing the wall of the sleeve into a groove 30.

The inner sleeve is shown as provided with a spiral slot 32 and the outer sleeve is shown as provided with a spiral slot 34. It will be observed that the spiral slots 32 and 34 are shown as of opposite pitch. As illustrated, the slot 32-is of right hand pitch and the slot 34 is of left hand pitch, and the pitch of slot 34 is shown as steeper than that of slot 32. When these sleeves are nested together in their normal relation as shown in Figure 4 it will be observed that these slots register at intervals so as to form openings leading from the inside of the inner sleeve to the outside of the outer sleeve, and if one sleeve is rotated while the other is held fixed, each of these registering openings travel in a spiral path involving an axial motion and a rotational motion. A pin 36 is shown as positioned within the inner sleeve, and this pin is provided with an angularly related portion 38 at one end thereof that is shown in Figure 3 as extending through one of the aforementioned openings so that it is simultaneously engaged by the walls of the slots 32 and 34. It will therefore be observed that on rotating one of the sleeves 24 and 26 in relation to the other the extension 36 will travel along a spiral path and in doing so it will cause the pin 3 6 to` travel axially downward as shown inl Figure 3, vand this axial motion is used to move the lead.

It will further be observed that the inner sleeve 26 is shown as having a portion 21 thereof extending beyond thel sleeve 24, and this portion, which is -shown as knurled for purposes of ready handling, is also shown as divided at its end by a slot 40, and the two jaws that are thereby formed at the end of the inner sleeve 26 may be closed suiiiciently so as to frictionally engage a lead 42 that is inserted into the inner sleeve.`

Such a construction is shown in Figure 5, in which the lead is shown'asof such diameter that it is spaced from the inner walls of the tube 26, and the end portions of jaws 42 are turned inwardly so as to engage the lead at such end portions. i

It will now be obvious that if the knurled portion 21 is grasped and rotated while the sleeve 24 is held stationary (as for instance where it is in place in the casing I0), the result will be that the pin 36 is caused to travel axially within the inner sleeve, its direction of travel depending on the direction of rotation of the part 21. If it is caused to travel downward as shown in Figures 3 and 5 it will ultimately strike the end 0f the lead 42 and will push the lead outward against the frictional resistance of the jaws 40. On retracting the pin 36 the lead may be pushed in. By referring to Figures l and 2 it will be observed that whenever a lead holder is in its projected position, its part 21 is available for manipulation.

It will be observed that the spiral slot 36 of the inner spiral tube 26 is shown as opening outl The tube 26 is next slipped over the projecting end of pin 36 and is then turned, while being pushed inward until the portion 32 thereof enters the spiral slot 32. Ojn turning tube 2t it 'will now spiral its way into place within the tube 2t, and when in place it may be held there by forming the groove 3B. If the slot 32 were made so as to Y terminate short of the upper end of the tube this manner of assembly would be impossible, and more complicated methods employed.

The law controlling the axial movement of the l, projector pin 38 `(or that of the lead) may be expressed as follows;

tan el M"tan A|tan ismA where M :axial movement ofthe projector pin 33 slot with the axis of the spiral a fthe angle made by tnefwaus of the other spiral slot with the axis of the spiral Pa=the pitch (that is, the axial distance between two consecutive turns of the spiral) of the spiral of angle A.

The relation existing between F, the force to be applied at the circumference of the knurled thumbpiece 2li (assuming its diameter to be the same as that of the imaginary cylinder within which liesthe theoretical point at which pressure may be assumed to be transmitted fr om the walls of the spiral slots to the projecting pin 36), and R, the resistance to movement of the projecting pin 36, is

' tan A-I-tan B From these formulae it may be deduced that by making the pitch of both spiral slots small, whereby A and B become large, the turning force on the thumb piece 21 may be made as small as desired. Further that the force may be decreased by increasing either A or B alone.

However it further appears that M, the rate of travel of the pin 36 is dependent on the relative magnitudes of A and B. This is clear if the formula is writtenin the form 1 tan B X PA necessaryior B to increase in order. to increase the rate of movement of projector pin 36. In

" other words the pitch of the other spiral must be decreased. l

Practical considerations, however, require that the speed of travel of the lead be not too low,

and by my invention Iaim to attain adequate speed of travel, small size of parts coupled with adequate strength and small power needed for their operation. It will be seen that by decreasing the inclination of the spiral slots itis possible to decrease the force needed at the thumb piece 21 to secure movement of the lead, and

would have to be* =the angle made bythe wallsvof one spiral;y

therefore it is possible by the use of two spiral slots to have the thumb piece of very small diameter, which yet will permit sufficient `force to be applied even by the fingers of a child, to cause advance of the lead, and it is due t'o this fact that the diameter of the thumb piece can be held to such small dimensions that I am enabled to accommodate four lead carriers within the confines of a pencil having a case of ordinary diameter.

It will further be seen that by making the inner spiral slot of a lesserv pitch than the outer one that the walls of the inner tube may be made thinner and thereby a small diameter of the thumb piecesecured without sacrificing the strength of the whole. The steeper pitch of the outer spiral on the other hand provides adequate speed of travel without subjecting the tubes to undue strain. Another advantage that is gained by decreasing the pitch of the inner slotis that it reduces the tendency of the pressure on the lead, as when writing, to push the lead into the holder.

On turning tube 2t against the resistance of the pin in slot 32 the tube will tend to spread in a,4 manner that increases its diameter and its length, and it is further to be noted that the steeper the pitch., of the spiral, the greater will be the stresses tending to distort the spiral, and

the effect of such stresses is especially great on the end of the` tube 26 due to the open spiral slot 32 therein. f vInorder to minimize these effects it is advisable to decrease the pitch of the spiral slot, and it is further advisable to place the tube 26 within the tube 24, which. is inherently strongerv be? cause the spiral slot 34 terminates short of its end. `I have found that, if walls are made of adequate thickness that such outer tube will have sufficient strength to resist all tendency to spread, either because of the action of pin 36 against the walls of its slot 34, or because of. the spreading tendency of the inner tube 26 which would tend to expand outward against the tube 24.

Since the outer tube is stronger, the pitch of its slot 34 may be increased without unduly weakening it, and thereby a 'Sufcient speed of travel of th'e projecting pin may be obtained, while the inner tube may have a spiral of very low pitch,

l without unduly decreasing the speed of travel of K the lead.

- extension ofthe magazine I3.

In Figure 7, I have shown another form of my invention resembling that of Figure 3 to some extent and for that reason similar parts have been similarly numbered except that primes have been added to the numbers. It will however be observed that the outer tube 34 is shown as having a straight slot 34' therein, instead of the spiral slot 34 of Figure 3. In accordance with the principles heretofore discussed it will be obvious that thespeed of movement of the angularly bent portion 38 of the projecting pin 36 in relation to the speed of movement of the thumb piece is increased over what it would be if the slot 34' were a spiral slot pitched oppositely to the spiral slot 32 of the tube 26. The construction however will still have many of the advantages enumerated in connection with the other form of my invention because the inner spiral maybe made of very slight pitch so as to compensate for the absence of pitch in the outer spiral. As before the walls of the inner spiral are spread and prevented from spreading by the walls of the outer tube, and therefore the inner spiral may be made of comparatively thin material, whereby the diameter of the entire assembly may be kept very small and only slightly greater than that of the lead.

It will be understood that While I have described one embodiment of my invention the same may be embodied in many other forms as will be obvious to those skilled in the art and that the disclosure herein is not to be interpreted as limiting but by way of illustration only and that I do not limit myself in any other way than as called for by the language of the appended claims.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent, is:-

1. In a mechanical pencil, a tubular lead holder the bore of which has a diameter of the same order as that of the lead to be received therein and having a spiralslot of relatively slight pitch in the wall thereof, a lead propelling means slidable Within said lead holder adapted to engage the end of a lead positioned in said holder so as to force said lead outward when said means is correspondingly moved, said means having a portion thereof positioned Within the said spiral slot, and said lead holder having the outer end thereof split, so as to provide clamping jaws adapted to hold the lead in frictional engagement therewith, and said lead holder also having an annular groove provided on the outside thereof, an outer sleeve positioned so as to surround said lead holder and having a portion thereof engaging said annular groove so as to hold said lead holder and sleeve against relatively axial movement without preventing their relative turning, and said sleeve also having a spiral slot therein pitched oppositely to and of greater pitch than the spiral slot of the lead holder, and a portion of said lead propelling means being positioned within the spiral soit of the sleeve, whereby when said lead holder is rotated relatively to said sleeve the lead propelling means will be caused to travel within said lead holder in a direction determinedl by the direction of rotation.

2. In a mechanical pencil, a tubular lead holder, the bore of which has a diameter of the same order as that of the lead to be received therein and having a spiral slot in the wall thereof, a lead propelling means slidable within said lead holder` adapted to engage the end of a lead positioned in said holder so as to force said lead outward when said means is correspondingly moved, said means having a portion thereof positioned within the said spiral slot, and said lead holder having the outer end thereof split, so as to provide clamping jaws adapted to hold the lead in frictional engagement therewith, an outer sleeve positioned so as to surround said lead holder, and having a spiral slot therein pitched oppositely to the spiral slot of the lead holder, and a portion of said lead propelling means being positioned within the spiral slot of the sleeve, whereby when said lead holder is rotated relatively to'said sleeve the lead propelling means will be caused to travel within said lead holder in a direction determined by the direction of rotation.

3. For use in a mechanical pencil, a lead holder comprising two coaxial sleeves, one of which surrounds the other, and said sleeves being relatively rotatable but fixed axially, the inner of saidl sleeves having a bore the diameter of which is substantially the same as that of a lead positioned therein, and each of said sleeves having a spiral slot in the walls thereof, said spiral slots being of opposite and unequal pitch, and a lead propelling member within the inner sleeve adapted to engage an end of said lead and having a portion thereof positioned within the slots of both of said sleeves.

4. A lead holder for a mechanical pencil comprising an inner tube for receiving a lead, said tube being of a diameter to 'closely surround the lead, an outer tube rotatably mounted on said inner tube and closely surrounding the same, means for preventing relative axial movement of said tubes, each of said tubes having a spiral slot in the walls thereof, and the spiral slot of one of said tubes being of opposite pitch to that of the other, a member slidable within the said inner tube and having a portion thereof projecting into the respective slots of said two tubes.

HANS MAUCHER.

Images