Ejector pin for ejecting shaped parts

Abstract

The invention relates to ejector pins for ejecting shaped parts from hollow molds. The ejector pins have a shank with a shank longitudinal axis, and the shank has, at least along a portion, one or more recesses such that the first one or more recesses extend(s) substantially helically about the shank longitudinal axis.

Description

EJECTOR PIN FOR EJECTING MOLDED PARTS Field of the invention

[0001] The present invention relates generally to casting tools, and for example to an ejector pin for ejecting molded parts. Background of the invention

[0002] In injection molding and die casting (e.g., for molding plastics and low-melting metal alloys), the common task is to remove the solidified molded part from the mold at the end of the casting process. This is often done using one or more ejector pins mounted on a movable support plate, each extending through a hole in the mold. Typically, the ejector pins are flush with the inner wall of the mold when the ejector is not activated.

[0003] Ejection of a cast part occurs after opening the mold by moving the support plate with the ejector pin(s) toward the mold, causing the ejector pin(s) to penetrate the mold and eject the molded part. Ejector pins are known, for example, from EP 3 722 068 A1 or DE 20 2004 018 293 U1.

[0004] The shaft of ejector pins is designed to be inserted into a bore or recess in the casting mold. This makes it possible to insert the ejector pins into a desired position in the casting mold, eject the cast part or molded part, and remove the ejector pins therefrom. Put simply, the ejector pins form a body that can be inserted into and removed from the casting mold and is, for example, at least temporarily mounted in a floating manner in the casting mold. In particular, the outer contour of the ejector pin can be designed to be substantially complementary to the inner contour of the casting mold, thus essentially enabling a positive fit, although a certain hollow space may exist between the ejector pin, in particular the shaft of the ejector pin, and the casting mold, in particular a recess or bore in the casting mold.

[0005] This results in air not flowing out or escaping completely, especially during the introduction of the casting material into the mold cavity. This can lead to unwanted air remaining in the molded part, and thus the mold cavity is not completely filled with the casting material, especially in the area of ​​the ejector pin. This leaves unwanted imperfections in the cast part.

[0006] In order to allow unwanted air to escape from the molded part more effectively via the cavity or by means of the cavity between the ejector pin and the mold, the state of the art knows ejector pins with a so-called vent.

[0007] With ejector pins of this type, however, it is important to ensure that no casting material or other unwanted material accumulates between the shank of the ejector pin and the wall of the casting mold. If casting material is introduced into the mold cavity, it is possible that not only air but also casting material can undesirably enter said cavity. This effect can even be exacerbated by the venting known from the prior art. As a result, the casting mold, in particular the borehole, and / or the shank of the ejector pin, can become contaminated with casting material. This contamination increases the maintenance and / or cleaning effort with regard to the casting mold, the borehole and / or the shank. This particularly implies downtime in the production of molded parts. Brief description of the invention

[0008] It is an object of the present invention to avoid or mitigate the above-described disadvantages of previously known ejector pins. The invention relates to devices according to independent claim 1. The dependent claims relate to preferred embodiments.

[0009] The invention relates to an ejector pin for ejecting a molded part from a casting tool, comprising a shaft with a longitudinal shaft axis. The shaft has one or more recesses along at least a partial section. The one or more recesses extend essentially helically around the longitudinal shaft axis.

[0010] The shaft may be substantially a body of revolution. For example, the shaft may be substantially cylindrical or substantially conical. The shaft may be substantially an extrusion. The shaft may be substantially pyramid-shaped. The shaft may be substantially cuboid-shaped. The shaft may be substantially rectangular. The shaft may be substantially paraboloidal.

[0011] The shaft may comprise one or more shaft sections. In the case of multiple shaft sections, the multiple shaft sections may have different shapes. Thus, a shaft section may be cylindrical, conical, frustoconical, or conical. Alternatively, the at least one shaft section may extend over the (entire) length of the shaft. The multiple shaft sections may each be connected to one another, arranged adjacently, or spaced apart.

[0012] The shaft may comprise at least a first, second, and third shaft portion, wherein the second shaft portion is adjacent to one end of the first shaft portion and adjacent to one end of the third shaft portion. The first shaft portion is substantially cylindrical and has a first diameter. The third shaft portion is substantially cylindrical and has a third diameter. The second shaft portion is substantially frustoconical or conical, and the second shaft portion is configured to allow a transition between the first shaft portion and the third shaft portion. The transition may be a smooth or continuous transition. Simply put, the second shaft portion does not have a jump in a cross-section of the second shaft portion during the smooth or continuous transition.In other words, the second shaft section has a fourth and fifth diameter, with the fourth diameter substantially corresponding to the first diameter, and the fifth diameter substantially corresponding to the third diameter. Alternatively or additionally, the second shaft section has an opening angle. The opening angle is designed to facilitate the transition or rising transition.

[0013] The ratio between the first diameter and the third diameter can be, for example, between 1.1 and 4, preferably between 1.5 and 2.5.

[0014] The shaft longitudinal axis typically extends along the insertion direction of the shaft during operation. It can be an axis of symmetry of the shaft. The shaft longitudinal axis can be at least one axis of rotation of the shaft. The shaft longitudinal axis can comprise a rod axis (for example, analogous to rod statics). The rod axis can comprise the center of gravity of the shaft. The rod axis can comprise a connecting line of the geometric centers of gravity or the centers of mass of cross sections of the shaft. The shaft can be made of different materials or material compositions. The shaft can comprise different materials or material compositions with different material strengths or degrees of hardness. The degree of hardness can be a Rockwell hardness (HR). The degree of hardness can be determined according to EN ISO 6508-1. The degree of hardness can be determined in HRC.

[0015] The ejector pin may further comprise a head. The head may be integrally formed with the shaft. The head may be shaped such that the ejector pin can only be mounted in a complementary support plate in one specific installation position. The head may have an anti-twist feature so that the ejector pin is secured against twisting when mounted in a complementary support plate. Furthermore, the head may have pre-centering means. The head may have a support surface on its underside for resting on the support plate. The head and shaft may comprise different material strengths or hardnesses. The shaft may have a higher material strength or hardness than the head.

[0016] As described above, the shaft has one or more recesses along at least one partial section. In particular, the shaft can have one recess along at least the partial section. Alternatively, the shaft can have multiple recesses along at least the partial section.

[0017] The partial section can be a section or cutout of the shaft in the longitudinal direction of the shaft. The partial section can be essentially cylindrical, except for the recess. The partial section can be adjacent to one end of the shaft, in particular an end facing away from the head of the ejector pin.

[0018] The shaft is designed to be shortened from the free end to adapt to the mold. In some embodiments, the partial section extends over a length that represents 50% to 80% of the shaft length, preferably between 59% and 69%. This allows the remaining section to represent approximately half (e.g., between 45% and 55%) of the remaining shaft length even after shortening the shaft.

[0019] The subsection may comprise one or more subsections. In the case of multiple subsections, these may be connected, adjacent, or spaced apart from each other.

[0020] As described above, the one or more recesses extend or extend substantially helically around the shaft longitudinal axis. Helix-shaped can be screw-shaped. Helix-shaped can be spiral-shaped. In the case of a cylindrical shaft, the helix shape can be described by a curve that with a constant pitch around the cylinder's shell. As is known to those skilled in the art, a helix can be described by its pitch (the distance in the direction of the cylinder's axis by which the helix winds like a screw in one full revolution along the cylinder's axis), its pitch angle (also called the pitch angle), or its pitch (when the cylinder shell with the helix is ​​unwound into a plane, a straight line with the respective pitch is obtained).

[0021] The one or more recesses may extend along a substantially helical, screw-shaped, or helical path. The path may extend along a shaft surface. The path may extend along the subsection. The path may be spaced from the subsection or from a shaft surface. The subsection may be a shaft surface.

[0022] The one or more depressions can result from removing or abrading material from a master shape of the shaft, e.g. by grinding. The master shape of the shaft can refer to the shape of the shaft without depression(s). The one or more depressions can be one or more notches. The one or more depressions can be produced using a grinding process. The one or more depressions can occur during the manufacture of the shaft. The depression can have a substantially constant shape or cross-section along the partial section. The one or more depressions can comprise at least one cross-section.

[0023] The cross-section is preferably oriented in a normal plane of the line section or a normal plane of the shaft's longitudinal direction. The cross-section can be oriented perpendicular to the shaft's longitudinal axis or to the line section.

[0024] The helical shape of the one or more recesses can have a pitch angle. In the case of multiple recesses, these multiple recesses can have the same pitch angle. Alternatively, the multiple recesses can each have a different pitch angle. Preferably, the pitch angle for the one or more recesses is constant along the shaft's longitudinal axis. Alternatively, the pitch angle can be constant in sections and / or can have a dependency along the shaft's longitudinal axis.

[0025] The helical shape of each recess preferably has a pitch and / or a slope. The pitch can be greater than, equal to, or less than the length of the section.

[0026] In the case of multiple recesses, these can be arranged at a distance from one another. The spacing can extend over at least part of the subsection. The spacing can extend over the subsection.

[0027] In some embodiments, the one or more recesses can be configured to be substantially concave with respect to a cross-section perpendicular to the shaft's longitudinal axis. The one or more recesses can be configured to be substantially concave in sections with respect to a cross-section perpendicular to the shaft's longitudinal axis.

[0028] In other embodiments, the one or more recesses can be configured to be substantially planar or rectilinear with respect to a cross-section perpendicular to the shaft's longitudinal axis. The one or more recesses can be configured to be substantially planar or rectilinear in sections with respect to a cross-section perpendicular to the shaft's longitudinal axis.

[0029] A depression of the one or more depressions can be partially planar or rectilinear with respect to a cross-section perpendicular to the shaft's longitudinal axis, and partially concave with respect to a cross-section perpendicular to the shaft's longitudinal axis. At least one depression of the plurality of depressions can be substantially planar or rectilinear with respect to a cross-section perpendicular to the shaft's longitudinal axis. At least one other depression of the plurality of depressions can be substantially concave with respect to a cross-section perpendicular to the shaft's longitudinal axis.

[0030] The concave shape can essentially be or include a circular arc shape or a parabolic shape.

[0031] The circular arc shape can have or represent a radius of between 20 and 30 mm. The circular arc shape can include a radius. The ratio between the radius and a radius of the shaft can be, for example, between 4 and 26, preferably between 10 and 20.

[0032] The one or more depressions may represent a depression compared to an original shape of the shaft without the depression between 0.01 mm and 0.03 mm. The one or more depressions may represent a depression (at the deepest point) compared to an original shape of the shaft without the depression of approximately 0.02 mm. The one or more depressions may represent a depression compared to an original shape of the shaft without the depression -1 - between 0.02 mm ± 0.003 mm. Preferably, the accuracy of the recess (in the radial direction along the shaft radius) is less than 5 mm. Such accuracy can be achieved over the entire length of the section using grinding processes. This further contributes to avoiding contamination and increasing the self-cleaning effect.

[0033] The one or more depressions may represent or include a depression relative to an original shape of the shaft without the depression of between 0.1% and 2.0% of the radius of the shaft.

[0034] The one or more recesses can be a plurality of recesses. In particular, these multiple recesses can be an odd number. This allows—with an even distribution of the recesses around the shaft circumference—that no two recesses are opposite each other in terms of the shaft circumference. In particular, there can be 3, 5, or 7 recesses.

[0035] Recesses of the plurality of recesses may have or include the same pitch angle.

[0036] The plurality of recesses may have multiple pitch angles. At least one first recess of the plurality of recesses may have a first pitch angle. At least one second recess of the plurality of recesses may have a second pitch angle that is not identical to the first pitch angle. This allows the helices to intersect and further increases venting performance.

[0037] The first and second pitch angles may differ in sign and / or magnitude. The helices with the first and second pitch angles may have the same helicity (i.e., pitch angles with the same sign) or opposite helicity (i.e., pitch angles with opposite signs). The magnitude or absolute value of the first pitch angle may be identical to or different from the magnitude or absolute value of the second pitch angle.

[0038] The first pitch angle can be a multiple of the second pitch angle. The multiple can be essentially an integer multiple. The essentially integer multiple can be rounded to two, three, or four. The essentially integer multiple can be two, three, or four.

[0039] The shaft may further comprise a coating of the shaft. The shaft may further comprise a coating of the section. The coating may be a low-friction coating. The coating may have a friction value between 0.1 and 0.15.

[0040] The coating may comprise a carbon layer. The coating may comprise an amorphous carbon layer, in particular a diamond-like carbon (DLC) layer. This allows for maintenance-free or low-maintenance use of the ejector pin.

[0041] The shaft may further comprise an end face, wherein the end face represents a shape of the molded part or the casting mold. The end face may be perpendicular or inclined to the longitudinal direction of the shaft.

[0042] The shaft may also include one or more circumferential grooves. This can further help prevent contamination and increase the self-cleaning effect.

[0043] The groove may, for example, extend or be oriented substantially in a plane perpendicular to the shaft's longitudinal axis. Alternatively or additionally, the groove may extend or be oriented tangentially along the circumferential portion of the shaft.

[0044] The groove can, for example, be arranged at one end of a section. A groove can be located between two sections. A groove can be located between two sections, and the groove can be connected to one end of a first section and to one end of a second section. In the case of multiple grooves, these can be connected to one another, adjacent to one another, or spaced apart from one another. Alternatively or additionally, the groove can be connected to, adjacent to, or spaced apart from one another with at least one recess.

[0045] The groove can be designed to have a fluid connection with at least one of the mentioned recesses. A groove can be designed to have a fluid connection between or with at least one recess of a first subsection. A groove can be designed to have a fluid connection between at least one recess of a first subsection and at least one recess of a second subsection.

[0046] The groove may be partially planar or linear with respect to a cross-section parallel to the shaft's longitudinal axis. Alternatively, it may be partially concave with respect to a cross-section parallel to the shaft's longitudinal axis.

[0047] The concave shape of the groove may be or comprise substantially a circular arc shape or an elliptical shape or a parabolic shape.

[0048] The circular arc shape of the groove can have a radius, for example a radius between 1 mm and 2 mm.

[0049] A groove can have a depth of between 0.02 mm and 0.3 mm compared to the original shape of the shaft without the groove. The groove can have a depth (at its deepest point) of approximately 2 to 10 times greater than the depressions described above compared to the original shape of the shaft without the groove.

[0050] The invention further relates to an ejector pin assembly for use with a casting mold, the assembly comprising at least one ejector pin according to the invention and a support plate configured to receive the ejector pin in a bore. The ejector pin assembly may further be configured to have a fluid connection between the bore and the casting mold. The fluid connection may be an air connection. The fluid may be air and / or casting material.

[0051] The mold cavity can at least partially represent a negative form of a mold. The mold cavity can be adjacent to the ejector pin. The mold cavity can be at least partially delimited by the ejector pin.

[0052] The cavity can further be designed so that the ejector pin can be at least partially movable. The cavity can be designed so that the ejector pin can be at least partially movable at least in a section of the cavity. The mobility can be translational. The mobility can be rotational. The mobility can be both translational and rotational.

[0053] The ejector pin assembly may further comprise at least one mold half. The mold half may at least partially form the mold cavity.

[0054] The at least one mold half may include a through-bore. The through-bore may include the cavity.

[0055] Ejector pins according to the invention are preferably compatible with other ejector pins. This allows the ejector pin or shaft disclosed herein to be used without adapting the support plate or mold.

[0056] The ejector pin according to the invention with a helix running around the circumference of the shaft allows for an even distribution of the load (e.g. due to friction between the shaft and the inner wall of the bore) around the circumference of the shaft, so that any wear can occur evenly. Furthermore, the ejector pin according to the invention allows the aforementioned contamination, in particular contamination by unwanted filler or casting material in the recess, to be reduced or avoided by the helical shape of the recess. In other words, the essentially helical recess has a self-cleaning effect compared to conventional vents: If the ejector pin is removed from the casting mold by movement (essentially translational along the longitudinal axis of the shaft), the contamination, in particular the unwanted filler or casting material, is carried between the ejector pin and the casting mold, in particular the bore, by the essentially helical recess.This results in a certain degree of self-cleaning of the cavity. Description of implementation examples

[0057] In the following, embodiments of the invention are described in more detail with reference to figures, wherein Figure 1 shows an ejector pin according to an embodiment; Figure 2 shows an ejector pin according to an embodiment; Figure 3 shows an ejector pin according to an embodiment; Figure 4 shows an ejector pin according to an embodiment; Figure 5 shows an ejector pin according to an embodiment; Figure 6 shows an ejector pin according to an embodiment; Figure 7 shows an ejector pin according to an embodiment; Figure 8 shows a shaft of an ejector pin according to an embodiment; and Figure 9 shows an ejector pin according to an embodiment.

[0058] In the following description of the embodiments, identical or similar components may have identical or corresponding reference numerals.

[0059] The term "may" or "can" refers in particular to an optional feature or optimal features of the invention. Accordingly, there is a An embodiment or disclosure of the invention that has the respective feature or features. This embodiment or disclosure may be combined, varied, or permuted in any manner with the other embodiments or disclosures above or below.

[0060] Figure 1 shows a view of an embodiment of an ejector pin 100 for ejecting a molded part from a casting tool. The ejector pin 100 comprises a head 102 and a shaft 104. The head 102 and the shaft 104 are each substantially cylindrical. In another embodiment, the head 102 is integrally formed with the shaft 104.

[0061] The shaft 104 comprises a shaft longitudinal axis 106. In this embodiment, the shaft longitudinal axis 106 is an axis of symmetry of the substantially cylindrical shaft 104.

[0062] The shaft 104 includes two planar ends. The two planar ends are arranged perpendicular to the shaft's longitudinal axis 106. A first end borders the head 102 or is delimited by the head 102. The other (second) end is a free end. In another embodiment, the free end may correspond to the molded part. In another embodiment, the free end may substantially correspond to a shape of the molded part.

[0063] The shaft 104 further comprises a subsection 108. The subsection 108 extends from the free end toward the head-side (first) end of the shaft. In this embodiment, the subsection 108 is substantially cylindrical. In another embodiment, the subsection 108 may comprise a cutout or section of a cylinder. The subsection 108 is a continuous subsection of the shaft 104.

[0064] The shaft 104 further includes a plurality of recesses 110. The plurality of recesses 110 extend substantially helically around the shaft's longitudinal axis. In this exemplary embodiment, the plurality of recesses 110 comprise five substantially helical recesses. The plurality of recesses 110 have the same pitch angle. This means that the plurality of recesses 110 do not overlap, but rather run parallel.

[0065] Furthermore, in the example shown, the plurality of recesses 110 are evenly spaced within the section 108: With respect to the circumference of the shaft, they are They are arranged at equal angular intervals (each one-fifth of the total circumference, i.e., 360° / 5 = 72°) from each other. With respect to the shaft length axis, they are arranged at equal pitch differences (offset by one-fifth of the pitch of each helix).

[0066] Figure 2 shows another view of the embodiment of the ejector pin 100.

[0067] Figure 3 shows a view of another embodiment of the ejector pin 300 for ejecting a molded part from a casting tool. The ejector pin 300 comprises a head 302 and a shaft 304 with a longitudinal shaft axis 306. The shaft has, at least along a partial section 308, a plurality of recesses 310 extending substantially helically around the longitudinal shaft axis.

[0068] In this exemplary embodiment, the plurality of recesses 310 are or comprise a first plurality 310.2 and a second plurality 310.4 of recesses. The first plurality of recesses 310.2 is a number of two substantially helical recesses. The second plurality of recesses 310.4 is a number of three substantially helical recesses. The recesses of the first plurality of recesses 310.2 have a first pitch angle, i.e., they run parallel to one another. The recesses of the second plurality of recesses 310.4 have a second pitch angle, i.e., they run parallel to one another.

[0069] In this embodiment, the first pitch angle and the second pitch angle differ, so that the helices of the first plurality of recesses 310.2 and the helices of the second plurality of recesses 310.4 intersect.

[0070] The recesses of the first plurality of recesses 310.2 are not evenly spaced (but rather offset at different angular intervals along the circumference or pitches along the shaft axis). The recesses of the second plurality of recesses 310.4 are evenly spaced (i.e., offset at equal angular intervals of one-third of a turn along the circumference).

[0071] Figure 4 shows a view of another embodiment of the ejector pin 400 for ejecting a molded part from a casting tool. The ejector pin 400 comprises a head 402 and a shaft 404 with a shaft longitudinal axis 406. The shaft has, at least along a partial section 408, a plurality of recesses 410 that extend essentially helically around the shaft longitudinal axis.

[0072] In this embodiment, the plurality of recesses 410 are a first plurality 410.2 and a second plurality 410.4 of recesses.

[0073] The first plurality 410.2 is a number of three substantially helical recesses. The recesses of the first plurality of recesses 410.2 have a first pitch angle. The recesses of the first plurality of recesses 410.2 are evenly spaced from one another (i.e., at equal angular intervals along the circumference or offset by pitches along the shaft axis).

[0074] The second plurality 410.4 is a number of three substantially helical recesses. The recesses of the second plurality of recesses 410.4 have a second pitch angle. The recesses of the second plurality of recesses 310.4 are evenly spaced from one another (i.e., at equal angular intervals along the circumference or offset by pitches along the shaft axis).

[0075] The embodiment of the ejector pin 400 according to Figure 4 differs from the embodiment of the ejector pin 300 according to Figure 3 by different recesses, in particular by the uniform spacing of the first number of recesses.

[0076] At the end of the partial section 408, which essentially corresponds to the free end of the shaft 406, a depression of the first plurality 410.2 and a depression of the second plurality 410.4 are arranged or located opposite one another. "Arranged or located opposite one another" means that a depression of the first plurality 410.2 is displaced or rotated by 180° relative to a depression of the second plurality 410.4, with the shaft longitudinal axis 706 as the axis of rotation. Furthermore, at the end of the partial section 408, the first plurality 410.2 and the second plurality 410.4 are arranged evenly over or along the partial section 408. In other words, at the end of the partial section 408, the first plurality 410.2 and the second plurality 410.4 are arranged or distributed evenly along the circumference or cross-section of the shaft.This allows for uniform ventilation across the cross-section of the shaft.

[0077] Figure 5 shows a sectional view of an embodiment of a shaft 504 with a partial magnification. The shaft 504 is a shaft of one of the previously described embodiments. The sectional view in Figure 5 shows a cross-section of the substantially cylindrical shaft 504 normal to the shaft longitudinal axis. In other words, the sectional view shows a cross-section of the shaft 504 that is perpendicular to the shaft longitudinal axis. The shaft 504 is therefore shown as an essentially circular cross-section.

[0078] Figure 5 further shows a detail of the shaft 504 on its left-hand periphery in the illustration. The shaft includes a recess 510. The recess 510 can be one of the multiple recesses from the previous embodiments.

[0079] The recess 510 comprises a recess 516 compared to an original shape of the shaft without the recess. In this exemplary embodiment, the recess 510 is substantially concave. The concave shape is substantially a circular arc shape 512, wherein the circular arc shape comprises a radius R.

[0080] Figure 6 shows a sectional view of another embodiment of a shaft 604. The shaft 604 can be a shaft in the previously mentioned embodiments. The shaft 604 is substantially cylindrical. The sectional view in Figure 6 shows a cross-section of the substantially cylindrical shaft 604 normal to the shaft's longitudinal axis. In other words, the sectional view shows a cross-section of the shaft 604 perpendicular to the shaft's longitudinal axis.

[0081] Figure 6 further shows a detail of the shaft 604. The shaft includes a recess 610. In this exemplary embodiment, the recess 610 is configured or constructed to be substantially planar or rectilinear, 614. The recess 610 includes a recess 616 compared to an original form of the shaft without the recess.

[0082] Shaft 600 differs from shaft 500 in particular in the design of the recess. Shaft 500 comprises a substantially concave recess. Shaft 600 comprises a substantially planar or rectilinear recess.

[0083] Figure 7 shows a view of another embodiment of the ejector pin 700 for ejecting a molded part from a casting tool. The ejector pin 700 comprises a head 702, a shaft 704 with a shaft longitudinal axis 706. The shaft 704 comprises two planar ends. The two planar ends are arranged at right angles to the shaft longitudinal axis 706. A first end borders the head 702 or is delimited by the head 702. The other (second) end is a free end. In another embodiment, the free end may coincide with the molded part. In another embodiment, the free end may substantially correspond to a shape of the molded part. In one embodiment, the head 702, the shaft 704, and the shaft longitudinal axis 706 are a head, a shaft, and a shaft longitudinal axis from a previous embodiment.

[0084] The shaft 704 further includes a first section 708a and a second section 708b. The second section 708b extends from the free end toward the head-side (first) end of the shaft. The first section 708a and the second section 708b are spaced apart from each other.

[0085] The shaft 704 has, at least along the first partial section 708a, a plurality of recesses 710a that extend substantially helically around the shaft longitudinal axis 706. In this exemplary embodiment, the plurality of recesses 710a are a first plurality 710a.2 and a second plurality 710a.4 of recesses. For example, the plurality of recesses 710a correspond to a plurality of recesses from a previous exemplary embodiment, in particular the plurality of recesses 410 shown in Figure 4.

[0086] The shaft 704 has, at least along the second partial section 708b, a plurality of recesses 710b that extend substantially helically around the shaft longitudinal axis 706. In this exemplary embodiment, the plurality of recesses 710b are a first plurality 710b.2 and a second plurality 710b.4 of recesses. In one exemplary embodiment, the plurality of recesses 710b correspond to a plurality of recesses from a previous exemplary embodiment, in particular the plurality of recesses 410 shown in Figure 4.

[0087] The shaft 704 further includes a groove 718. The groove 718 is located within the spacing of the first section 708a and the second section 708b. In other words, one end of the first section 708a and one end of the second section 708b are adjacent to the groove. Furthermore, one end of the plurality of recesses 710b and one end of the plurality of recesses 710a are adjacent to the groove 718. In the illustrated example, the position of the groove 718 along the shaft axis is approximately 75% of the total length from the shaft head. Generally, the groove is preferably located in a range of 60% to 75% of the shaft length. This allows for some shortening of the shaft, so that the shortened shaft also has the groove.

[0088] The groove 718 extends substantially in a plane perpendicular to the shaft longitudinal axis 706 and rectilinearly along the circumference of the shaft 706.

[0089] In this embodiment, the number of the first plurality 710b.2 and the number of the first plurality 710a.2 are the same. Furthermore, the pitch angle of the first plurality 710b.2 of the helical recesses and the pitch angle of the first plurality 710a.2 of the helical recesses are the same.

[0090] Furthermore, the plurality of recesses 710a and the plurality of recesses 710b are arranged relative to one another such that the plurality of recesses 710a and the plurality of recesses 710b are continuous, except for the spacing of the first subsection 708a and the second subsection 708b. Simply put, the plurality of recesses 710b are a continuation of the plurality of recesses 710a and vice versa, with the continuation being interrupted by the spacing of the first subsection 708a and the second subsection 708b.

[0091] Figure 8 shows a section of a view of a shaft 804 of another embodiment of an ejector pin for ejecting a molded part from a casting tool. In this respect, the shaft 804 is comparable to the shaft 704 shown in Figure 7.

[0092] The shaft 804 includes a first section 808a, a second section 808b, and a groove 818. The first section 808a and the second section 808b are spaced apart from each other. The groove 818 is disposed between the first section 808a and the second section 808b. The groove 818 extends between the first section 808a and the second section 808b.

[0093] Furthermore, the shaft 804 has a recess 810a at least along the first partial section 808a and a recess 810b at least along the second partial section 808b. The first partial section 808a may correspond to a partial section of a preceding embodiment and / or the second partial section 808b may correspond to a partial section of a preceding embodiment.

[0094] Furthermore, Figure 8 shows in dashed lines a (notional) continuation 824 of the depression 810a and a (notional) continuation 824 of the depression 810b within the spacing between the first partial section 808a and the second partial section 808b. The notional continuation 824 of the depression 810a is a continuous continuation of this and has the same parameters as those of the depression 810a. The notional continuation 824 of the depression 810b is a continuous continuation of this and has the same parameters as those of the depression 810b. In one embodiment, the depression 810a and the Each recess 810b is helically shaped, and the respective parameter includes at least one of pitch, lead angle, pitch angle, displacement, and pitch. In this embodiment, the respective parameters of recess 810a and recess 810b are identical.

[0095] The recess 810a and the recess 810b are arranged such that they merge into one another, except for the spacing of the first partial section 808a and the second partial section 708b. Thus, the dashed extensions 824 are essentially congruent.

[0096] The groove 818 includes a recess 822 compared to an original shape of the shaft 826 without the groove 818. In this embodiment, the recess 822 is substantially concave. The concave shape is substantially a circular arc shape 820, wherein the circular arc shape has a radius RI. In one embodiment, the groove corresponds to the groove 718 in the embodiment shown in Figure 7.

[0097] Figure 9 shows a view of another embodiment of the ejector pin 900 for ejecting a molded part from a casting tool. The ejector pin 900 comprises a head 902 and a shaft 904 with a shaft longitudinal axis 906. The shaft 904 comprises two planar ends. The two planar ends are arranged at right angles to the shaft longitudinal axis 906. A first end borders the head 902 or is delimited by the head 902. The other (second) end is a free end. In another embodiment, the free end may correspond to the molded part. In another embodiment, the free end may substantially correspond to a shape of the molded part.

[0098] The shaft 904 includes a first 928.2, second 928.4, and third shaft section 928.6. The first shaft section 928.2 is adjacent to the first end of the shaft at one end and to an end of the second shaft section 928.4 at another end. The other end of the second shaft section 928.4 is adjacent to one end of the third shaft section 928.6. The other end of the third shaft section 928.6 is adjacent to the free end of the shaft. Simply put, the first 928.2, second 928.4, and third shaft sections 928.6 divide the shaft 904 along the shaft longitudinal axis 906.

[0099] The first shaft section 928.2 has a substantially cylindrical shape and a Diameter D2. The second shaft section 928.4 has a substantially truncated cone shape or conical shape and an opening angle a. The third Shaft portion 928.6 has a substantially cylindrical shape and a diameter D4. The second shaft portion 928.4 is further configured to provide a smooth or continuous transition between the first shaft portion and the third shaft portion.

[0100] In the illustrated embodiment of the ejector pin 900, the diameter Dl is approximately 10 mm and the diameter D4 is approximately 6 mm.

[0101] The third shaft section 928.6 has, at least along the partial section 908, a plurality of recesses 310 that extend substantially helically around the shaft longitudinal axis 906. The plurality of recesses 310 may be a plurality of recesses in a preceding embodiment.

Claims

CLAIMS 1. An ejector pin for ejecting a molded part from a casting tool, comprising a shaft with a shaft longitudinal axis, wherein the shaft has one or more recesses at least along a partial section, characterized in that the one or more recesses extend substantially helically around the shaft longitudinal axis.

2. Ejector pin according to claim 1, wherein the one or more recesses have at least one pitch angle.

3. Ejector pin according to claim 1 or 2, wherein the one or more recesses are substantially concave in shape with respect to a cross-section perpendicular to the shaft longitudinal axis.

4. Ejector pin according to claim 3, wherein the concave shape is substantially a circular arc shape.

5. Ejector pin according to claim 4, wherein the circular arc shape has a radius and a ratio between the radius and a radius of the shaft is between 4 and 26.

6. Ejector pin according to claim 1 or 2, wherein the one or more recesses are substantially planar with respect to a cross-section perpendicular to the shaft longitudinal axis.

7. Ejector pin according to one of claims 1 to 6, wherein the one or more depressions represent a depression relative to an original shape of the shaft without the depression of between 0.3% and 1.0% of the radius of the shaft.

8. Ejector pin according to one of claims 1 to 7, wherein the one or more recesses is a plurality of recesses.

9. The ejector pin of claim 8, wherein the plurality of recesses is an odd number.

10. Ejector pin according to claim 8 or 9, wherein the plurality of recesses have a same pitch angle.

11. The ejector pin of claim 8 or 9, wherein at least a first recess of the plurality of recesses has a first pitch angle; and at least a second recess of the plurality of recesses has a second pitch angle.

12. Ejector pin according to one of claims 1 to 11, further comprising a low-friction coating of the partial section, in particular with a friction value between 0.1 and 0.

15.

13. The ejector pin of claim 12, wherein the low-friction coating comprises an amorphous carbon layer.

14. Ejector pin according to one of claims 1 to 13, wherein the shaft is substantially cylindrical, in particular has a diameter between 1 mm and 20 mm.

Images