Pin

Abstract

The invention relates to a pin with at least one sleeve-shaped component having a longitudinal axis and a base. According to the invention, 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 runs concentrically to the longitudinal axis.

Description

[0001] The invention relates to a pin with at least one sleeve-shaped component having a longitudinal axis and a base.

[0002] Pins of the type mentioned above are well known. The sleeve-shaped component, which can be a protector or a shaft, for example, is manufactured from plastic by injection molding. Processes with indirect core centering at the injection point are often used, with the injection point being located at the bottom of the sleeve-shaped component. The geometry used in this case stabilizes the core in the mold during the injection process and prevents it from being pushed to the side. However, bottlenecks occur, which increase the pressure. The result is a limited or non-existent process window and higher energy requirements. If a higher-viscosity plastic is used, the material can freeze during injection before the mold is completely filled. Particularly in the case of PET (polyethylene terephthalate), streaks often form on the surface of the sleeve-shaped component.

[0003] The invention is based on the object of developing the pin of the type mentioned at the outset 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 when PET is used, the formation of streaks on the surface of the sleeve-shaped component is limited or even avoided.

[0004] According to the invention, the stated object is achieved with a pin of the type mentioned at the outset 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 runs concentrically to the longitudinal axis.

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

[0006] The invention is based on the discovery that by varying the wall thickness of the base along the closed line, a better distribution of the material during injection can be achieved, thereby reducing pressure and expanding the process window. Furthermore, energy consumption is reduced. It also prevents the material from freezing during injection before the mold is completely filled when using higher-viscosity plastic. Streaking is reduced or even eliminated altogether.

[0007] Finally, the inventive design 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 plastic.

[0008] The manner of changing the wall thickness of the base along said line can be chosen as desired in a suitable manner. According to the invention, it is preferably provided that the wall thickness of the base increases and decreases again two, three or more times along the line.

[0009] The base may have two, three or more first regions along the line, the wall thickness of which is greater than in second regions lying in the circumferential direction between adjacent first regions.

[0010] According to a further preferred embodiment of the invention, it is provided that the wall thicknesses of the first regions are of equal size.

[0011] This ensures a particularly even distribution of the injected material.

[0012] According to the invention, the first regions can, in principle, be arranged at any location on the base, as long as the effects described above are achieved. However, according to the invention, it is preferred to arrange the first regions such that an imaginary cylindrical surface runs through at least one of the first regions in the middle between the longitudinal axis and the inner wall of the sleeve.

[0013] With this arrangement, the first areas are very effective in the sense of the invention.

[0014] According to a particularly preferred embodiment of the invention, it is provided that the first regions are evenly distributed along the line.

[0015] Uniform distribution means that the angular distances between adjacent first regions along the line are equal. For two first regions, the angular distances are 180°. For three first regions, the angular distances are 120°.

[0016] The even distribution of the first areas also ensures an even distribution of the material during injection.

[0017] The wall thickness of the base in the first regions can, in principle, be chosen arbitrarily, 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 greater than in the second regions, with 1.5 ≤ k ≤ 2.5, preferably 1.7 ≤ k ≤ 2.3, more preferably 1.9 ≤ k ≤ 2.1.

[0018] The above measures allow the use of a wide variety of materials for the production of the pen, and in particular the sleeve-shaped component. This applies particularly to PET. Therefore, according to the invention, it is preferably provided that the sleeve-shaped component is made of PET. Furthermore, the entire pen can also be made exclusively of PET, which considerably simplifies its recycling.

[0019] According to the invention, the PET is further preferably recycled PET.

[0020] According to the invention, the sleeve-shaped component can be a protector or a shaft of the pin.

[0021] Furthermore, the invention also provides a sleeve-shaped component of a pin of the type described above.

[0022] Furthermore, the invention also provides a casting mold for the sleeve-shaped component of the pin of the type described above.

[0023] Finally, the invention also provides a casting core of the above casting mold.

[0024] In the following, the invention is explained in more detail using a preferred embodiment with reference to the accompanying drawings. Fig. 1 is a partially sectioned schematic view of the bottom of a pen protector according to a preferred embodiment of the invention, Fig. 2 a schematic longitudinal section view of the schooner according to Fig. 1, Fig. 3 an excerpt from Fig. 2, on an enlarged scale, Fig. 4 a schematic longitudinal section view of the pen with the protector according to the Fig. 1 to 3, Fig. 5 a core of a casting mould for the production of the protector according to the Fig. 1 to 3 and Fig. 6 a mold for producing the protector according to the Fig. 1 to 3.

[0025] The pen 10 shown in the drawing includes a sleeve-shaped shaft 12 and a lead 14 located within a cartridge 16 and held by a lead holder 18. The lead 14 is advanced by extending the lead holder 18. By turning the shaft 12 against the cartridge 16, a screw nut 20 held stationary in the shaft 12 is also turned. The lead holder 18 has a threaded rod on the side facing away from the lead 14, which is inserted into the screw nut 20. The cartridge 16 and the lead holder 18 are secured against mutual rotation by ribs / webs on both components. Thus, the lead 14 can be retracted or extended by turning the cartridge 16 and the shaft 12. The longitudinal axis of the pen 10 is designated by the letter L. Finally, the pin 10 includes a protector 22.

[0026] The protector 22 is sleeve-shaped and has a bottom 24. The inner wall of the protector 22 is designated by the reference number 26.

[0027] The wall thickness of the base 24 is not constant along a closed line 28 concentric with 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 the intermediate regions 31, 33, 36.

[0028] In the embodiment of the protector shown in the drawings, the wall thickness W is 1 in the first areas 30, 32, 34 0.7 mm, whereas the wall thickness W 2 in the intermediate areas 31, 33, 36 is 0.35 mm. In other words, in the protector 22 shown in the drawings, the wall thickness W 1 twice as large as the wall thickness W 2 .

[0029] As in particular Fig. 1, the protector 22 has three areas with the larger wall thickness W 1 which are evenly distributed, ie with the same angular spacing of 120° along the line 28 around the longitudinal axis L. They all have the same wall thickness W 1 The same applies to the intermediate areas, which also have the same wall thickness, although the wall thickness W 2 is.

[0030] An imaginary cylindrical surface 38 in the middle between the longitudinal axis L and the inner wall 26 of the protector 22 runs through the regions 30, 32, 34 in the protector 22 shown in the drawings. In other words, the regions 30, 32, 34 are located approximately in the middle between the longitudinal axis L and the inner wall 26.

[0031] The cap 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.

[0032] The above statements regarding the protector 22 also apply to the shaft 12. This means that the shaft 12 also has a base with the features described in detail above in connection with the base 24 of the protector 22.

[0033] Fig. 5 shows a core 40 with a recess 42. The core 40 is used in the injection molding of the protector 22.

[0034] In addition, Fig. 6 a mold 44 . Again, the mold 44 is a mold used for injection molding the protector 22. The core 40 is in the Fig. 6 is introduced from the left into the casting mold 44. This creates a channel at the right end of the cavity of the casting mold 44 between the Fig. 5 shown recess 42 on the core 40 and the projection at the lower end part of the cavity; here the melt is fed. The injection point 46 is located in the Fig. 6 bottom right.

[0035] When casting the protector 22 with the mold 44 and the core 40 therein, the channels 42 and 46 serve to form the regions 30, 32 and 34, respectively, of the bottom 24 of the protector 22.

[0036] A comparable mold and core are used for injection molding the shaft 12.

[0037] The features of the invention disclosed in the above description, the claims and the drawings may be essential both individually and in any combination for the realization of the invention in its various embodiments.

Claims

[1] Pin with at least one sleeve-shaped component (12, 22) having a longitudinal axis (L) and a base (24), characterized by 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 runs concentrically to the longitudinal axis (L). [2] Pen according to claim 1, characterized by that the wall thickness (W 1 , W 2 ) of the floor (24) along the line (28) increases and decreases two, three or more times. [3] Pen according to claim 1 or 2, characterized by that the base (24) has two, three or more first regions (30, 32, 34) along the line (28), the wall thickness (W 1 ) is greater than in second regions (31, 33, 36) lying in the circumferential direction between adjacent first regions. [4] Pen according to claim 3, characterized by that the wall thicknesses (W 1) of the first areas (30, 32, 34) are of equal size. [5] Pen according to claim 3 or 4, characterized by that the first regions (30, 32, 34) are arranged such that an imaginary cylindrical surface (38) runs 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 one of claims 3 to 5, characterized by that the first regions (30, 32, 34) are evenly distributed along the line (28). [7] Pen according to one of claims 3 to 6, characterized by 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), with k 1.5 ≤ k ≤ 2.5, preferably 1.7 ≤ k ≤ 2.3, more preferably 1.9 ≤ k ≤ 2.

1. [8] Pen according to one of the preceding claims, characterized by that the sleeve-shaped component (12, 22) is made of PET. [9] Pen according to claim 8, characterized bythat the PET is recycled PET. [10] Pen according to one of the preceding claims, characterized by that the sleeve-shaped component (12, 22) is a protector (22) or a shaft (12) of the pin. [11] Sleeve-shaped component of a pin (10) according to one of the preceding claims. [12] Casting mold (44) for the sleeve-shaped component (12, 22) of the pin (10) according to one of the preceding claims. [13] Casting core (40) of the casting mold (44) according to claim 12.

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