US2188130A - Point forming device for the leads of pencils and the like - Google Patents

Description

Jan. 23, 1940. G. BAIER ET AL POINT FORMING DEVICE FOR THE LEADS 0F PENCILS AND THE LIKE Filed June 26, 1939 Ila 2.

Patented Jan. 23, 1940 UNITED STATES POINT FORMING DEVICE FOR THE LEADS 0F PENCILS AND THE LIKE Georg Baier and Georg Koppel, Nuremberg,

Germany Application June 26, 1939, Serial No. 281,270 In Germany February 9, 1939 8 Claims.

This invention relates to improvements in pointing: devices as used more particularly for pointing the leads of propelling pencils or pencils adapted to use lead refills, but the device herein described may also be used for other purposes where a fine point is required on a rod of relatively small diameter. The form of the invention herein shown is more particularly designed for use with a propelling pencil in which the lead is clamped or held firmly in a chuck or collet provided in a tip piece on the pencil holder and is also preferably held at its inner end within the barrel of the holder. In this way the lead is heldagainst both rotational and axial movement within the holder. For the purpose of pointing the lead, this lead is projected from the tip for about half an inch and then clamped at 'both its tip end and its inner end, The tip end of the lead is indicated at A in Figure 1 of the accompanying drawing together with the end of the tip piece of the pencil holder. The pointing device is usually held in the left hand, using, say, the thumb and first finger, whilst the pencil holder is held in the right hand with its end bearing on the palm of the hand so that the pencil holder can be readily turned by the thumb and first finger of the right hand. Conversely it will be evident that the pencil holder may be held in the left hand and the pointing device in the right hand.

With such a device, it will be readily recognized thatin the usual course of events it is impossible to ensure that the pointing blades and the pencil axis run true to one another, say with the degree 01' accuracy and steadiness obtainable if the pointing tools and the pencil were chucked in a lathe. The result is that in all lead pointing devices of the portable or pocket type as hitherto known, the leads have been as frequently broken as successfully pointed and a long tapered fine point, such as required by mechanical draughtsmen, has been unobtainable. A good point for a mechanical draughtsman would, for instance, be one having a 6 m./m. long taper on a 1.8 m./m. lead. It is the object of the present invention to obtain with a pocket type of pointing device, even points of such a fine character without dam ger of breakage of the brittle leads and withthe exercise of reasonable care and normal skill.

Broadly stated, the invention may be said to consist of a pointing device for pencil leads and the like characterised in that a plurality of radially arranged pointing blades are mounted with free radial movement in a floating carrier within an outer housing and co-operate with means, preferably of a resilient character, for retaining said blades and carrier in proper pointing relation. The housing and the carrier are suitably apertured to admit the lead or like rod to be pointed. The blades are conveniently four in number and the cutting edges lie on the surface of a cone which widens towards the apertures in the housing and carrier. The outward radial movement of each blade is confined by the inner wall of the housing and the inner radial 10 movement is confined by abutment of each blade at its extreme point end with its opposite number in the plurality. The positioning of the blades is finally determined by abutment at a third point which is located at or near the wide end of the point cone and is constituted by shoulders on the blade which abut against shoulders on the floating carrier and thereby retain the blades at a constant diameter of cone at the wide end of the pointing cone.

The invention further comprises other constructional features which assist in the attainment of the object of this invention as set out above and which will be more readily understood from the following description of a form of the invention as illustrated in the accompanying drawing in which:

Figure 1 is a sectional elevation of a pointing device in accordance with this invention.

Figure 2 is a sectional plan on the line 2-2 of 0 Figure 1.

Figure 3 is a detached elevation of the floating body which carries the pointing blades and is shown elevated from, its spring pressed seating.-

Figure 4 is a plan view of the top end of the tapered housing in Figure 1 with the top end of the cap removed to reveal the shutter or valve which prevents the egress of fine powdered graphite or the like when the pointer is not in use.

In the form of the invention herein illustrated four sharpening or pointing blades 5 of suitable steel and having their cutting edges ground at a suitable angle are freely mounted to slide in substantially radial guide slots ill in a cup shaped carrier body 6. For the sake of lightness of weight and to give steady guidance to the blades 5, the cup shaped body 6 is here shown as having four radial webs or ribs 1 through which the slots lllpass. The slots I0 have each one face Illa radial whilst the opposite face is offset from the radial by the thickness of the pointing blades 5. The blades 5 also project radially beyond the outer wall of the cup shaped carrier body 6 as seen most clearly in Figure 3. When the blades 5 are assembled in the body 3, the cutting edges lie on the surface of the desired point cone which has its wide end at the upper part of Figure 1. At this wide end of the point cone the blades 5 have abutment shoulders 8 which bear on abutment shoulders 3 formed in the radial slots -10, the diameter of the point cone at its wide end being therefore determined by these abutments 8 and 9. At their lower ends in Figure 1, the pointing blades 5 have also shoulder portions 12 somewhat similar to theshoulders 8, but these shoulders [2 do not abut on the corresponding shoulder ll of the slot I0. In this way the point end of the: cone may swivel or float a limited amount from the axis of the cup shaped body 6, but this amount is very limited indeed; The main point of the clearance between the shoulders H and I2 is to ensure that each blade 5 finds an abutment against its opposite number at the point end of the cone. The floating cup shaped body 8 with its complement of four pointing blades 5 is inserted in a housing l4 which is here shown as having a conical inner surface or bore. This however is not essential as it may have a partially spherical bore conforming for instance to the zone d of the sphere indicated at l5 inFigure 3 by dot and dash lines. In all cases the bore of the housing I4 is tapered so that it widens downwardly from its upper end which has the aperture 23 through which the lead or like rod to be pointed is entered into the housing. In Figure 3, it has been assumed that the blade 5 has been removed from the front slot It) so as to reveal the abutments 9 and H.

By this device it will be seen that the blades 5 are mounted in the slots III of the carrier body 5 so as to be free to slide radially but are located by abutment at three points in the case of each blade, namely:

(a) The abutment faces at 8 and 3.

(b) The abutment of each blade 5 at its point end against the opposite blade.

() The abutment of the external projecting portion of each blade with the taper bore of the housing l4.

The outer face of the blades where they contact with the housing bore is rounded or curved slightly so that the cup shaped carrier body 8 can roll or swivel slightly within the tapered housing 14 and thereby accommodate itself and the blades 5 to any slight departure from the true of the lead or rod during its rotation when in the act of pointing. The blades Sand cup shaped body 6 are pressed resiliently towards the narrow end of the tapered housing I 4 by a seating ll acted upon by a spring i9. The seating I i has slots l8. to clear the projecting parts of the blades 5. The spring l9 has its abutment in a cup formed in a screwed closing cap 20 on the wide end of the housing I4.

The blades 5 are conveniently provided with holes 2| to enable them to be readily removed when desired for cleaning or sharpening purposes. The cup shaped carrier 6 has the central aperture 22 which forms the guide bush for the lead to be sharpened and comes opposite the aperture 23 in the housing M. It is generally preferred to provide a closing cap for the aperture 23 so as to prevent undesired egress of the very fine powdered graphite resulting from the pointing operation.

The cap and shutter mechanism for closing the'aperture 23 comprises a shutter plate 24 pivoted at 25 on a pin fixed to the top of the housing H. The plate 24 has a slot 26 engaging a pin 21 on the cap 28 which is rotatable. The cap 28 is lapped over a beading 29 at the upper end of the housing l4 so that the cap 28 is held on the housing l4 but can rotate thereon. The shutter 24 has an aperture 30 which in the position shown in Figure 4 registers with the aperture 23 and the central hole 3| of the cap 28. When the cap is turned through an angle of about 90 degrees in the direction of the arrow 32 the shutter 24 is swung about its pivot 25 and closes the apertures 23, 3| after the manner of a sluice valve. In this way the fine powder which settles in the base of cap 20 is prevented from finding egress from the housing I4. When it is desired to clean the fine powder out. the cap 20 is unscrewed and the carrier and blades 5 may be readily extracted and cleaned. The screwed cap 20 may be adjusted for the purpose of adjusting the resilient pressure applied by the end of the slots I8 in which the point ends of the blades 5 nest.

In operation when a lead is inserted the blades -5 may each execute a pivotal movement of the lower point end about a centre located at the shoulders 8 and 3. The carrier body 6 is also free to assume a position in which the cone on which the blade edges lie is co-axial with the lead inserted at the aperture 23. This hand tool may in consequence operate with the precision of a machine or lathe.

We claim:

1. A pointing device for pencil leads and like and spring means acting on said blades and carrier to press the blades resiliently against the inner walls of the said housing.

2. A pointing device as claimed in claim 1 characterised in that the interior of the.housing is of conical form widening from the apertured end.

3. A pointing device as claimed in claim 1 characterised in that the pointing blades are curved where they contact with the interior wall of the housing.

4. A pointing device as claimed in claim 1 characterised in that the interior of the housing is of conical form widening from the apertured end and the pointing blades are curved where they contact with the said interior conical wall.

5. A pointing device for pencil leads and like rods having an outer housing, a floating carrier body within said housing and a plurality of pointing blades mounted in said carrier and each free to execute a pivotal movement at the point end of said blades.

6. A pointing device as claimed in claim 1 characterised in that the floating carrier body is cup shaped with the open end of said cup opposite the aperture in said carrier so as to permit the egress of fine powder resulting from the pointing operation.

'7. A pointing device as claimed in claim 1 characterised in that the spring means comprise in combination, a slotted bush embracing the end 2,188,1sq I of the carrier body with the point ends of the blades nested in said s1ots. a spring pressingthe ends of said slots against the point ends of the blades and a screwed cap on the housing to term.

an abutment for said spring.

8. A pointing device for leads of pencils and like rods as claimed in claim 1 characterised in that the" hofising is prdvided w'itfi? cana'nd shutter-mechanism forclqsing asds'lged the apei'ture therein thrbugh which the lead orL-the like is v admitted;

G ese BAIERL GEORG K6PPEL.

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