Pen

Abstract

The invention relates to a pen with at least one sleeve-shaped component which has a longitudinal axis and a base. According to the invention, it is provided that the wall thickness of the base changes along a closed line which lies on the surface of the base facing the interior of the sleeve-shaped component and extends concentrically to the longitudinal axis.

Description

[0001] PEN

[0002] The invention relates to a pen with at least one sleeve-shaped component which has a longitudinal axis and a base.

[0003] Pens of the aforementioned type are known. The sleeve-shaped component, which can, for example, be a protector or a shaft, is manufactured of plastics by injection molding. Processes with indirect core centering at the injection point are often used, wherein the injection point is located at the base of the sleeve-shaped component. Due to the geometry used, the core is stabilized in the mold during the injection process and is not pushed to the side. However, bottlenecks occur, whereby the pressure increases. The result is a limited to no process window and higher energy requirements. If higher-viscosity plastics are used, the material can freeze during injection before a complete filling of the mold is achieved. In particular in the case of PET (polyethylene terephthalate), streaks often form on the surface of the sleeve-shaped component. The invention is based on the task of further developing the pen of the aforementioned type in such a way that the problems explained in detail above do not occur during injection molding, in particular a sufficiently large process window is achieved, the energy requirement is reduced and, in particular in the case of using PET, the formation of streaks on the surface of the sleeve-shaped component is limited or even avoided.

[0004] According to the invention, the task set is solved with a pen of the aforementioned type in that the wall thickness of the base changes along a closed line which lies on the surface of the base facing the interior of the sleeve-shaped component and extends concentrically to the longitudinal axis.

[0005] In other words, the sleeve-shaped component is given a contour that solves the injection molding problems explained in detail above. This inasmuch as the contour of the component corresponds to the contour of the casting mold.

[0006] The invention is based on the realization that by changing the wall thickness of the base along the closed line, a better distribution of the material can be achieved during injection, whereby the pressure drops and the process window increases. The energy requirement is, moreover, reduced. It also prevents the material from freezing during injection if higher viscosity plastics are used, before a complete filling of the mold is achieved. The formation of streaks is reduced or even avoided.

[0007] Finally, the molding according to the invention of the base of the sleeve-shaped component leads to greater freedom in the choice of the ratio of wall thickness to length, especially in the case of highly viscous plastics.

[0008] The type and method of changing the wall thickness of the base along said line can be selected in any suitable manner. According to the invention, it is preferable for the wall thickness of the base to increase and again decrease two, three or more times along the line.

[0009] In so doing, along the line, the base can have two, three or more first regions, the wall thickness of which is greater than in second regions located between adjacent first regions in the circumferential direction. According to a further preferred embodiment of the invention, it is provided that the wall thicknesses of the first regions are of equal size.

[0010] In so doing, a particularly even distribution of the injected material is achieved.

[0011] According to the invention, the first regions can, in principle, be located at any position on the base as long as the effects described above are achieved. According to the invention, it is however preferred to arrange the first regions in such a way that an imaginary cylindrical shell surface extends through at least one of the first regions in the middle between the longitudinal axis and the inner wall of the sleeve.

[0012] With this arrangement, the first regions are very effective in the sense of the invention.

[0013] According to a particularly preferred embodiment of the invention, it is provided that the first regions are evenly distributed along the line.

[0014] Uniform distribution is understood to mean that the angular distances between adjacent first regions along the line are the same. In the case of two first regions, the angular spacing is therefore 180°. In the case of three first regions, the angular spacing is 120°.

[0015] The even distribution of the first regions also ensures an even distribution of the material during injection.

[0016] The wall thickness of the base in the first regions can in principle be chosen as desired, as long as the above-mentioned effects are achieved. According to the invention, the wall thickness of the base in the first regions is preferably k times as great as in the second regions, wherein 1.5 < k < 2.5, preferably 1.7 < k < 2.3, more preferably 1.9 < k < 2.1.

[0017] The above measures enable the use of a wide variety of materials to manufacture the pen and, in particular, the sleeve-shaped component. This applies in particular to PET. According to the invention, it is therefore preferably provided that the sleeve-shaped component is made of PET. The entire pen can, moreover, also be made exclusively of PET, which considerably simplifies its recycling. According to the invention, the PET is preferably recycled PET.

[0018] According to the invention, the sleeve-shaped component can be a protector or a shaft of the pen.

[0019] The invention, moreover, also provides a sleeve-shaped component of a pen of the type described above.

[0020] The invention, additionally, also provides a casting mold for the sleeve-shaped component of the pen of the type described above.

[0021] Lastly, the invention also provides a casting core of the above casting mold.

[0022] The invention is elucidated in more detail hereinafter based upon a preferred embodiment example with reference to accompanying drawing with further details. Wherein,

[0023] Fig. 1 shows a schematic partially sectioned view of the base of a protector of a pen according to a preferred embodiment of the invention,

[0024] Fig. 2 shows a schematic longitudinal sectional view of the protector according to Fig. 1,

[0025] Fig. 3 shows a section from Fig. 2, in an enlarged scale,

[0026] Fig. 4 shows a schematic longitudinal sectional view of the pen with the protector according to Fig. 1 through Fig. 3,

[0027] Fig. 5 shows a core of a casting mold for producing the protector according to Fig. 1 through Fig. 3 and

[0028] Fig. 6 shows a casting mold for producing the protector according to Fig. 1 through Fig. 3.

[0029] A sleeve-shaped shaft 12 and a refill 14, which lies within a cartridge 16 and is held by a refill holder 18, belong to the pen 10 shown in the drawing. The advancement of the refill 14 is brought about by pushing out the refill holder 18. By twisting the shaft 12 against the cartridge 16, a screw nut 20 held stationary in the shaft 12 is also twisted. The refill holder 18 has a threaded rod on the side facing away from the refill 14, which threaded rod is inserted into the screw nut 20. The cartridge 16 and the refill holder 18 are secured against mutual rotation by ribs / webs on both components. This means that the refill 14 can be retracted or respectively extended by twisting the cartridge 16 and shaft 12. The longitudinal axis of the pen 10 is marked with the letter L. Lastly, a protector 22 belongs to the pen 10.

[0030] The protector 22 is sleeve-shaped and has a base 24. The inner wall of the protector 22 is marked with the reference number 26.

[0031] The wall thickness of the base 24 is not constant along a closed line 28 concentric to the longitudinal axis L on the surface of the base 24 facing the interior of the protector 22. Rather, there are regions 30, 32, 34 in which the wall thickness of the base 24 is greater than in regions 31 , 33, 36 lying in between.

[0032] In the embodiment of the protector shown in the drawings, the wall thickness Wi in the first regions 30, 32, 34 amounts to 0.7 mm, whereas the wall thickness W2 in the intermediate regions 31 , 33, 36 amounts to 0.35 mm. In other words, in the protector 22 shown in the drawings, the wall thickness W1 is twice as great as the wall thickness W2.

[0033] As can be seen, in particular, from Fig. 1, the protector 22 is provided with three regions with the greater wall thickness W1, which regions are distributed evenly, which is to say, with the same angular spacing of 120° about the longitudinal axis L, along the line 28. They all have the same wall thickness W1. The same applies to the regions in between, which likewise have the same wall thicknesses, wherein these are the smaller wall thicknesses W2.

[0034] An imaginary cylindrical shell surface 38 in the middle between the longitudinal axis L and the inner wall 26 of the protector 22 extends through the regions 30, 32, 34 in the protector 22 illustrated in the drawings. In other words, said regions 30, 32, 34 are located approximately in the middle between the longitudinal axis L and the inner wall 26.

[0035] The protector 22 shown in the drawings is made of recycled PET. The same applies to the other components of the pen 10, with the exception of the refill 14. The above statements relating to the protector 22 also apply to the shaft 12, which is to say, the shaft 12 also has a base with the features described above in detail in connection with the base 24 of the protector 22.

[0036] Fig. 5 shows a core 40 with a recess 42. The core 40 is used in the injection molding of the protector 22.

[0037] Fig. 6 moreover also shows a casting mold 44. In turn, the casting mold 44 is a casting mold that is used for the injection molding of the protector 22. The core 40 is inserted into the casting mold 44 from the left in Fig. 6. As a result, a channel is formed at the right-hand end of the cavity of the casting mold 44 between the recess 42 on the core 40 shown in Fig. 5 and the protrusion at the lower end part of the cavity; this is where the molten mass is fed. The injection point 46 is located at the bottom right in Fig. 6.

[0038] The channels 42 and 46 serve to form the regions 30, 32 or respectively 34 of the base 24 of the protector 22 when casting the protector 22 with the casting mold 44 and the core 40 found therein.

[0039] A comparable casting mold and a comparable core are used for the injection molding of the shaft 12.

[0040] The features of the invention disclosed in the above description, claims and drawings may be essential, both individually and in any combination, for the implementation of the invention in its various embodiments.

Claims

CLAIMS1. Pen with at least one sleeve-shaped component (12, 22), which comprises a longitudinal axis (L) and a base (24), characterized in that the wall thickness of the base (24) changes along a closed line (28) which lies on the surface of the base (24) facing the interior of the sleeve-shaped component (12, 22) and extends concentrically to the longitudinal axis (L).

2. Pen according to claim 1 , characterized in that the wall thickness (Wi , W2) of the base (24) increases and again decreases two, three or more times along the line (28).

3. Pen according to claim 1 or claim 2, characterized in that, along the line (28), the base (24) has two, three or more first regions (30, 32, 34), the wall thickness (Wi) of which is greater than in second regions (31 , 33, 36) located between adjacent first regions in the circumferential direction.

4. Pen according to claim 3, characterized in that the wall thicknesses (Wi) of the first regions (30, 32, 34) are of equal size.

5. Pen according to claim 3 or claim 4, characterized in that the first regions (30, 32, 34) are arranged in such a way that an imaginary cylindrical shell surface (38) extends through at least one of the first regions in the middle between the longitudinal axis (L) and the inner wall (26) of the sleeve-shaped component (12, 22).

6. Pen according to any one of claim 3 through claim 5, characterized in that the first regions (30, 32, 34) are evenly distributed along the line (28).

7. Pen according to any one of claim 3 through claim 6, characterized in that the wall thickness of the base (24) in the first regions (30, 32, 34) is k times as great as in the second regions (31 , 33, 36), wherein k 1.5 < k < 2.5, preferably 1.7 < k < 2.3, more preferably 1.9 < k < 2.1.

8. Pen according to any one of the preceding claims, characterized in that the sleeveshaped component (12, 22) is made of PET.

9. Pen according to claim 8, characterized in that the PET is recycled PET.

10. Pen according to any one of the preceding claims, characterized in that the sleeveshaped component (12, 22) is a protector (22) or a shaft (12) of the pen.

11. Sleeve-shaped component of a pen (10) according to any one of the preceding claims.

12. Casting mold (44) forthe sleeve-shaped component (12, 22) of the pen (10) according to any one of the preceding claims.

13. Casting core (40) of the casting mold (44) according to claim 12.

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