Extension for pencils with worn leads

Abstract

An extension for pencils with wearing leads, formed from a thin-walled hollow profile. The inner cross section is adapted to the shape of a pencil. One or more slots of appropriate length in the longitudinal direction at an end of the extension where the tapered end of the pencil is located and a slight linear reduction in the cross section approximately over the length of one or more slots. Longitudinal raised sections in the form of triangular, square, and/or semi-circular prisms, directed inwardly. The height of the raised sections may increase in the direction of insertion of the pencil and dig into the pencil slightly when the pencil is inserted. The height of the raised sections is reduced linearly to zero at the end of the extension where the pencil is inserted. Inwardly bent or protruding retaining springs arranged on the inner surface of the extension.

Claims

1. An extension for a pencil with a wearing lead, the extension comprising: a thin-walled hollow profile forming a body of the extension, said body having an inner surface and an outer surface, and said body having a first end and a second end between a longitudinal direction of said body; said body having an inner cross-section configured to accommodate the pencil, and said first end being configured to accommodate an insertion of the pencil into said body, and said second end being configured to project a writing end of the pencil; a tapered end section of said second end having at least one slot extending in said longitudinal direction; said tapered end section having a slight linear reduction in said inner cross-section over the length of said at least one slot in said longitudinal direction; at least one elevation arranged along at least a portion of said inner surface of said body in said longitudinal direction, said at least one elevation being configured to engage the pencil when the pencil inserted into said body; said at least one elevation having a cross-sectional form selected from the group consisting of triangular, square, and semi-circular, and said at least one elevation being a plurality of elevations, said elevations being arranged asymmetrically on opposite sides of said inner surface of said body, and said elevations having different cross-sectional forms; and a plurality of retaining springs arranged on said inner surface of said body, said retaining springs being configured to accommodate an insertion of the pencil into said body and to prevent the pencil from movement in a direction opposite of a direction of insertion.

2. The extension for pencils with wearing leads according to claim 1, wherein said at least one elevation has an inwardly extending height that increases along said longitudinal direction toward said second end of said body.

3. The extension according to claim 1, further comprising: a lockable cap for closing said first end of said body, said lockable cap having an end face with a circumference corresponding to a circumference around said outer surface of said body, a projection with a hollow profile extending perpendicularly from said end face, said projection having an outer circumference corresponding to an inner circumference of said inner surface of said body; and said projection having locking device configured to lock said lockable cap in said body, said locking device having a locking element configured to engage a further locking element on said body when said lockable cap is inserted into said first end of said body.

4. The extension according to claim 3, further comprising a clip arranged between said projection of said lockable cap and said inner surface of said body.

5. The extension according to claim 3, further comprising a magnet arranged in said lockable cap.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The figures show the following.

(2) FIG. 1A shows the extension for pencils with worn leads.

(3) FIG. 1B shows the lower, open end of the extension for pencils with worn leads with the detail of, for example, two slots 2 of appropriate length in the longitudinal direction in the surface of the sheath.

(4) FIG. 1C shows in detail a retaining spring 5.

(5) FIG. 1D shows in detail the cap 6 with the part of the catch 7a arranged on the cap 6 and the clip 8 in the joined position.

(6) FIG. 1E shows in detail the cap 6 with the part of the catch 7a arranged on the cap 6 and the clip 8 in the unjoined position.

(7) FIG. 2A shows a longitudinal section of the extension for pencils with worn leads.

(8) FIG. 2B shows in detail a retaining spring 5.

(9) FIG. 2C shows a cross section A-A of the extension for pencils with worn leads.

(10) FIG. 2D shows a cross section through the cap 6 with a visible magnet 9.

DETAILED DESCRIPTION OF THE INVENTION

(11) The extension for carpenter's pencils is preferably realized by a thin-walled hollow profile made of plastic with a suitable length, the inner cross section of which is adapted to the shape of the common pencil cross sections.

(12) To facilitate insertion, to compensate for manufacturing tolerances of the pencils with respect to the cross-sectional area, and for adequate fixing of the pencil in the extension, the above-mentioned features are expediently combined.

(13) As a first feature, the extension has one or more slots 2 at the lower open end of appropriate length in the longitudinal direction in the surface of the sheath and a slight, linear reduction 3 of the cross section approximately over the length of the slot or slots in the direction of the end.

(14) In this context, lower means the side of the extension at which the pointed end of the pencil is located, and upper correspondingly means the other side.

(15) In the extension, longitudinally directed elevations 4 are provided in the form of triangular, square and/or semicircular prisms, which are realized in a suitable number, arrangement and length as a function of the pencil cross-section.

(16) The height of the raised sections 4, which can become larger to a certain degree in the direction in which the pencil is inserted, is selected in such a way that it slightly grooves the pencil during insertion.

(17) To facilitate insertion, the height of the raised sections 4 on the side of the extension at which the pencil is introduced is reduced linearly to zero over an expedient length 4a.

(18) If more than one raised section 4 is provided, they should not be symmetrical with respect to one another or have different cross sections, as a result of which, for example after a rotation of a non-round pencil through 180° about its longitudinal axis, new grooves are formed during renewed insertion and adequate fixing is maintained.

(19) Another feature can be used when the pencil is inserted from the top into the extension and pulled out step-by-step, and in which the inner surface of the extension exhibits an expedient number and arrangement of inwardly bent or projecting small regions of the surface of the sheath of the extension, referred to here as retaining springs 5, which are connected to the remaining surface of the sheath on the side up to the upper extension end and are separated from the surface of the sheath in the remaining region. When inserting the pencil, these retaining springs 5 are pressed elastically outwards.

(20) After the end of the pencil has passed through the extension, the retaining springs 5 move back to their original positions, as a result of which upwards movement of the pencil is prevented, and the latter can be used continuously and almost completely.

(21) The upper open end of the extension can be closed with a lockable cap 6, the end face of which corresponds to the outer cross-sectional surface of the extension and on which there is a piece of a hollow profile which is arranged perpendicularly thereto, and which has an outer cross section which corresponds to the inner cross section of the extension, and which has a device for locking the cap 6 in the extension 1, comprising elements 7a and 7b, which are to be jointed together.

(22) If necessary, a clip 8 can be pushed on and fixed between the extension 1 and the end face of the cap 6.

(23) In a particular embodiment of the solution according to the invention, the arrangement of a magnet 9 in the cap 6 is proposed to lift small and difficult to access steel parts. This appears to be particularly expedient in the exemplary illustration of a carpenter's pencil.