DEVICE FOR THE MANUFACTURE OF SMALL-VOLUME TUBE PACKAGING BLANKS

Description

Technical field

[0001] The invention relates to a device for the production of small-volume tube packaging blanks. State of the art

[0002] Tube packaging is often formed from blanks produced using an extrusion process. An extrusion process is a forming process in which a workpiece is deformed by applying pressure. The flow direction of the material relative to the direction of die movement provides the basis for distinguishing between forward extrusion (material flow and die movement direction are the same), reverse extrusion (material flow and die movement direction are opposite), and transverse extrusion (material flow perpendicular to the die movement direction).

[0003] The production of a thin-walled metal tube by reverse extrusion is described in DE 29 32 016 A1. DE 40 26 921 A1 also describes a method for producing a thin-walled metal tube. In this case, production is carried out by extrusion using a circular blank, the material of which is made to flow by high pressure. During the extrusion process, the material of the blank flows both against and in the direction of pressure, with the material flowing in the direction of pressure forming the tube neck, while the material flowing against the direction of pressure forms the tube body.

[0004] US patent A-2,112,085 discloses a device according to the preamble of claim 1.

[0005] There has long been a desire to design metal tube packaging with the smallest possible volume, particularly in the medical and cosmetic sectors, where products are often required in small quantities. However, the production of small-volume metal tubes with a diameter of 10 mm or less presents various difficulties, leading to a high rate of defective products during the manufacturing process.

[0006] Therefore, there remains a need for manufacturing processes that allow small-volume metal tube packaging to be produced reproducibly in high quantities with low waste. Description of the invention

[0007] The present invention is based on the objective of providing a device for the production of tube packaging with which small-volume metal tube packaging can be produced reproducibly in high quantities with low waste. This objective is achieved according to the invention by the device for producing tube packaging blanks according to independent claim 1. Further advantageous aspects, details, and embodiments of the invention will become apparent from the dependent claims, the description, and the drawings.

[0008] The present invention provides a device for producing tube packaging blanks by extrusion. The device comprises a die, a punch, and an ejector. The punch includes a tool-receiving section, a shaft section, and a punch head. The shaft section, together with the punch head, is formed integrally from a material with a Rockwell hardness of at least 60 HRC, wherein the shaft section, at least in its portion intended for engagement with the die, has the form of a straight circular cylinder with a diameter of at most 10 mm. The die has an interior cavity bounded by a die base and a die wall, wherein the interior cavity forms the negative of the punch head, including the portion of the shaft section adjacent to the punch head and intended for engagement with the die.The die base has a perforation arranged concentrically around its circumference. The ejector engages positively in the perforation of the die base and closes the perforation flush with the die base.

[0009] According to the invention, the tube packaging blanks are manufactured by extrusion. In the extrusion process, the material from which the tube packaging blank is to be manufactured is inserted into the die in the form of a blank. According to the invention, the die base has an opening arranged concentrically to its circumference. The blank therefore does not lie completely flat on the die base, but is only supported by a circumferential ring projecting from the die wall. The material of the blank is caused to flow by the high pressure exerted by the die. Under this pressure, the material of the blank flows both against and in the direction of pressure. The material flowing in the direction of pressure forms the tube neck, while the material flowing against the direction of pressure forms the tube body.According to the invention, the ejector engages positively in the opening of the die base and closes the opening flush with the die base. A closure of the tube neck is formed on the surface of the ejector that closes the opening of the die base, which serves as a tamper-evident seal for the subsequently manufactured tube packaging.

[0010] The one-piece design of the shank section and punch head, as provided for in the invention and manufactured from a single piece of material, completely eliminates the tool breakages frequently observed in two- or multi-part devices known from the prior art. It has been found that by using a one-piece press punch, small-volume metal tube packaging blanks can be produced in high quantities with minimal rejects using the extrusion process. While the one-piece design of the shank section and punch head according to the invention does not allow for the replacement of the punch head, which may be necessary due to material wear, as is known from the prior art, this disadvantage is far outweighed by the advantages of a one-piece design, which will be described in more detail below.

[0011] Furthermore, the use of a material with a Rockwell hardness of at least 60 HRC according to the invention makes it possible to manufacture the shaft section formed from this material, which has the shape of a straight circular cylinder at least in the section intended for engagement with the die, with an extremely small diameter of a maximum of 10 mm. Practical application shows that tube packaging blanks with a maximum tube body diameter of 10 mm can be produced with this type of press die. Production is achieved with high throughput and simultaneously extremely low reject rates of less than 3%.

[0012] A cylinder is a surface whose points are equidistant from a fixed straight line, the cylinder axis, namely the cylinder radius zr. The cylinder is also bounded by two parallel planes spaced apart by the cylinder height zh. If these planes are perpendicular to the cylinder axis, the result is a right circular cylinder with cylinder height zh and cylinder radius zr. The diameter of a right circular cylinder is twice the cylinder radius r.

[0013] Rockwell hardness is a unit of measurement for the hardness of technical materials, well-known to those skilled in the art. The unit HRC is composed of the acronym "HR" for "Hardness Rockwell," indicating the type of test method, and the letter "C," which denotes the scale and thus the test force and the test specimen. In the Rockwell C test, a diamond cone with a 120° tip angle is applied to the material being tested with a force of 1372.931 Newtons. The hardness of the material is then determined from the indentation depth t of the diamond cone using the formula Rockwell hardness = 100 - (t / 0.002 mm).

[0014] In principle, the device according to the invention can comprise a press ram that is constructed in two parts. In addition to the one-piece shank section and ram head, a tool holder section can be provided, which is screwed to the shank section and thereby firmly fixed. However, particular advantages arise when the entire press ram is formed in one piece from a material with a Rockwell hardness of at least 60 HRC. In this case, the tool holder section, shank section, and ram head are manufactured from the same material in a single piece. The entire press ram then exhibits extremely high resistance to mechanical stress, has a long service life, and is ideally suited for use in the device according to the invention. The tool holder section of the press ram is designed for mounting in the tool holder of a conventional press.

[0015] Particularly preferred are embodiments in which the material from which at least the shank section and punch head are manufactured in one piece, preferably the tool holder section, shank section, and punch head are manufactured in one piece, has a Rockwell hardness of at least 63 HRC. A shank section formed from such a material, which at least in its section intended for engagement with the die has the form of a straight circular cylinder, can be manufactured with an extremely small diameter of a maximum of 10 mm or, as will be explained in more detail below, even smaller diameters. In practical application, it has been shown that tube packaging blanks with a tube body diameter of less than 10 mm can be produced with this type of press punch. Production is carried out with high throughput and simultaneously with an extremely low reject rate of less than 3%.

[0016] Particularly preferred are embodiments in which, preferably, the tool holder section, shank section, and punch head are manufactured in one piece from the material used, a steel 1.3343 with a Rockwell hardness of 64 HRC to 66 HRC is employed. Such a steel is known to those skilled in the art and contains carbon, silicon, manganese, chromium, molybdenum, vanadium, and tungsten. The material 1.3343 is hardened at a temperature between 1190°C and 1230°C, thereby achieving a Rockwell hardness between 64 and 66 HRC.

[0017] Preferably, the shaft section, at least in the portion intended for engagement with the die, has a diameter of no more than 9.8 mm, more preferably no more than 9.5 mm, and most preferably no more than 9.2 mm. The use of a one-piece die with extremely high Rockwell hardness makes it possible to manufacture the die shaft section with extremely small diameters without any adverse effects on mechanical stability and service life. Since the diameter of the die essentially defines the diameter of the tube body of the tube packaging blank and the subsequently manufactured tube packaging, this method makes it possible to produce tube packaging with a very small diameter and thus a very small internal volume.Tests have shown that with increasing Rockwell hardness, especially when manufacturing the entire press die in one piece, increasingly smaller diameters of the shaft section can be achieved.

[0018] The die head preferably has a spray edge arranged in a region facing the shaft section, projecting circumferentially around the entire circumference of the die head. The spray edge projects, relative to the diameter of the shaft section, preferably between 0.1 and 0.2 mm, and particularly preferably 0.15 mm, beyond the surface of the shaft section around the entire circumference of the die head. The spray edge ensures that the metal, especially the aluminum, from which the tube packaging blank is manufactured, does not contact the shaft section, but rather that the tube body forms at the spray edge. The gap remaining between the spray edge and the die wall defines the wall thickness of the tube packaging blank.

[0019] According to a further, particularly preferred embodiment, the die head has the shape of a torus segment, at least in a partial region located between the injection edge and the shank section. A torus is known to be a bulge-shaped surface with a hole. Thus, a torus has the shape of a lifebuoy or donut. The surface of a torus is formed by the set of points that are at a fixed distance r from a circle with radius R, where r < R. In other words, the surface of a torus is obtained by rotating a circle about an axis that lies in the plane of the circle and does not intersect it. A torus segment, as used in this text, is obtained when not the entire circle is rotated about the axis, but only an arc of the circle.

[0020] As already explained, the device according to the invention is used in flow forming processes. The punch head exerts pressure on the blank inserted into the die, causing the blank material to flow both against and in the direction of pressure. The material flowing in the direction of pressure forms the tube neck, while the material flowing against the direction of pressure moves along the punch head to the injection edge and forms the tube body there. To ensure that the material moves as freely as possible and is evenly distributed over the entire circumference of the punch head towards the injection edge, according to a particularly preferred embodiment, at least a portion of the punch head adjacent to the injection edge is designed in the form of a torus segment. In this case, the blank material flows evenly distributed, unimpeded, and without material build-up from the punch head towards the injection edge.These advantages are particularly pronounced when the torus segment is a segment of a torus tube with a radius between 0.1 mm and 30 mm, preferably between 0.5 mm and 10 mm, and most preferably between 1 mm and 5 mm.

[0021] As explained, the die head has the shape of a torus segment in a portion of the area adjacent to the injection edge. Directly adjacent to the injection edge, i.e., in the area between the injection edge and the torus segment, the die head slopes linearly in a vertical section from the circumference of the injection edge to the circumference of the circular cylindrical section of the die head. The slope of this linear section in a vertical section determines the slope of the shoulder of the tube packaging blank and, consequently, the slope of the shoulder of the tube packaging. This slope is typically in the range of 20° to 40°, preferably 27°.

[0022] The present invention also includes the use of a device for producing a tube packaging blank by extrusion with a press punch, die and ejector as described above for producing tube packaging blanks, wherein the diameter of a tube blank body of the tube packaging blanks is a maximum of 10 mm.

[0023] In this text, the diameter of the tube blank body of a tube packaging blank is understood to be the maximum diameter of a cross-sectional area arranged perpendicular to the main axis of the tube blank body. The main axis of the tube blank body runs through the center point of the tamper-evident seal and forms the longitudinal axis of the cylindrically shaped tube blank body.

[0024] The present invention also comprises a method for producing a tube packaging blank by reverse extrusion, comprising the steps a) Providing a device for producing a tube packaging blank by extrusion with a press punch, die and ejector as described above, b) Inserting a blank into the die, c) Inserting the press punch and applying pressure to the blank, d) Removing the tube packaging blank from the die.

[0025] All the advantages and special features mentioned in connection with the various embodiments of the device according to the invention for producing tube packaging blanks by extrusion also apply equally to the inventive method for producing a tube packaging blank by extrusion. To avoid repetition, reference is made to the corresponding explanations above.

[0026] According to the invention, the die base has a perforation arranged concentrically to its circumference. The diameter of the blank is selected such that, after insertion into the die and before the insertion of the press punch, the blank rests on the circumferential ring projecting from the die wall. Subsequently, the press punch is inserted into the die and exerts pressure on the blank. The high pressure exerted by the press punch causes the blank material to flow. The material then flows, as already described, both against and in the direction of pressure. The material flowing in the direction of pressure forms the tube neck with tamper-evident seal, while the material flowing against the direction of pressure forms the tube body.

[0027] The blank is most preferably made of a metal, in particular aluminum, an aluminum alloy, or copper, with aluminum being especially preferred. The aforementioned materials, and aluminum in particular, exhibit ideal properties for use in extrusion processes for the production of small-volume tube packaging blanks. The material of the blank is selected by a person skilled in the art in the usual manner, depending on the properties desired for the finished tube packaging.

[0028] According to a further, particularly preferred embodiment, after step d), step e) involves forming an external thread in the region of the tube neck of the tube packaging blank by rolling or crimping. An M7 external thread proves to be particularly advantageous in connection with the desired small-volume tube packaging.

[0029] Finally, the present invention also comprises a tube packaging manufactured using one of the tube packaging blanks described above. Starting with a tube packaging blank manufactured according to an embodiment of the present invention, the finished tube packaging requires only the steps known to those skilled in the art, such as crimping the opening of the tube body of the tube packaging blank facing away from the tube neck.

[0030] Further developments, advantages and application possibilities of the invention also result from the following description of exemplary embodiments and from the figures. Brief description of the drawings

[0031] The invention will be explained in more detail below with reference to exemplary embodiments in conjunction with the drawings. The drawings show... Fig. 1 in schematic representation a vertical section through a device according to the invention for producing a tube packaging blank by extrusion; Fig. 2 in schematic representation a vertical section through a press die according to the present invention; Fig. 2 in detail a section of the press die according to Fig. 2A Fig. 3 shows a schematic vertical section through a die according to the present invention; Fig. 4A shows a schematic perspective view of a tube packaging blank produced using a device according to the invention; Fig. 4B shows a schematic perspective view of a tube packaging produced from the tube packaging blank according to the invention. Fig. 4A . Ways to implement the invention

[0032] The Figure 1Figure 1 shows a schematic vertical section through a device according to the invention for producing a tube packaging blank by extrusion. The device 1 comprises a die 2, a punch 3, and an ejector 4. The punch 3 comprises a tool holder section 3.1, a shaft section 3.2, and a punch head 3.3. The tool holder section 3.1 is designed for mounting in the tool holder of a conventional press. The die 2 is enclosed by a reinforcing ring 6 for mechanical stabilization. The ejector 4 engages positively in the opening 7 of the die base 2.1 and closes the opening 7 flush with the die base 2.1 (see also Figure 1). Figure 3 ).

[0033] In the illustrated embodiment, the tool holder section 3.1, the shank section 3.2 and the punch head 3.3 are formed in one piece from steel 1.3343 with a Rockwell hardness of 65 HRC.

[0034] The Figure 2A shows in schematic form a vertical section through the press die 3 of the Figure 1 The shaft section 3.2 has the shape of a straight circular cylinder with a diameter d = 9.5 mm over its entire extent up to a transition area 3.2.1 to the tool holding section 3.1.

[0035] In the Figure 2B This is a detailed section of the press die according to Figure 2AThe area of ​​the die head 3.3 is shown. The injection edge 5, located in the area of ​​the die head 3.3 facing the shaft section 3.2, is clearly visible. The injection edge 5 projects over the entire circumference of the die head 3.3 and extends 0.15 mm beyond the surface of the shaft section 3.2 relative to its diameter d. Since the diameter d of the shaft section is 9.5 mm in the illustrated embodiment, the diameter of the die head in the area of ​​the injection edge is 9.8 mm. The injection edge 5 ensures that the aluminum from which the tube packaging blank is produced does not contact the shaft section 3.2, but rather that the tube body is formed at the injection edge 5. This results in a tube packaging blank with an inner diameter of 9.8 mm.

[0036] The die head 3.3 has the shape of a torus segment in the sub-area 3.31 of the area of ​​the die head 3.3 facing the injection edge 5. As already explained, the surface of the torus is formed by the set of points that are at a fixed distance r from a circle with radius R, where r < R. The distance r is 1.3 mm in the illustrated embodiment.

[0037] The Figure 3 Figure 1 shows a die 2. The die 2 has an interior space 2.4 bounded by a die base 2.1 and a die wall 2.2, wherein the interior space 2.4 forms the negative of the punch head 3.3 including the section of the shaft section 3.2 adjacent to the punch head 3.3. The die base 2.1 has an opening 7 formed concentrically to the circumference of the die base 2.1. In the illustrated embodiment, the die base 2.1 consists only of a circumferential ring projecting from the die wall 2.2.

[0038] As already explained, the connection with the Figures 1 to 3 The described device is used in a compression molding process for the production of tube packaging blanks. For this purpose, the ejector 4 is first inserted from the underside of the die 2, facing away from the press die 3, into the opening 7 of the die base 2.1 and engages positively in the area facing away from the interior of the die 2.4. This closes the opening 7 of the die base 2.1, which is arranged concentrically to the circumference of the die base 2.1, flush with the surface.

[0039] The blank is then inserted into the die 2. The diameter of the blank is chosen such that, after insertion into the die 2, it rests on the circumferential ring projecting from the die wall 2.2 before the press ram 3 is inserted. Subsequently, the press ram 3 is inserted into the die 2 and pressure is applied to the blank. The high pressure exerted by the press ram 3 causes the aluminum of the blank to flow. The aluminum then flows both against and in the direction of pressure. The material flowing in the direction of pressure forms the tube neck, while the material flowing against the direction of pressure moves along the ram head 3.3 to the injection edge 5 and forms the tube body there. To ensure that the material moves as freely as possible and is evenly distributed over the entire circumference of the ram head 3.3 towards the injection edge, the section 3.31 of the area of ​​the punch head 3.3 adjacent to the injection edge 5 is formed in the form of a torus segment. The material of the blank flows evenly distributed, unimpeded and without material build-up from the punch head 3.3 towards the injection edge 5.

[0040] The thickness of the wall of the tube packaging blank is defined by the gap remaining between the injection edge 5 and the die wall 2.2.

[0041] The Figure 4AFigure 1 shows a schematic perspective view of a tube packaging blank 10 produced in the described manner. The tube body of the tube packaging blank 10 has a diameter dr of 9.8 mm. The tamper-evident feature 12, which forms on the surface of the ejector 4 that seals the opening 7 of the die base 2.1, is clearly visible. In a subsequent process step following the production of the tube packaging blank, an M7 external thread 11 is applied to the neck of the tube packaging blank 10 by rolling or crimping.

[0042] In Figure 4BThe schematic representation shows a perspective view of a small-volume tube packaging 13 produced from the tube packaging blank 10. Starting with the tube packaging blank 10, the only remaining step in producing the finished tube packaging 13 is to crimp the opening of the tube packaging blank facing away from the tube neck. Reference symbol list

[0043] 1 Device 2 Die 2.1 Die base 2.2 Die wall 2.4 Die interior 3 Punch 3.1 Tool holder section 3.2 Shank section 3.2.1 Transition area 3.3 Punch head 3.31 Partial section of the punch head 4 Ejector 5 Injection edge 6 Reinforcing ring 7 Opening 10 Tube packaging blank 11 External thread 12 Tamper protection 13 Tube packaging dDiameter of the stamp shaft drDiameter of the tube packaging blank rRadius of the torus segment HAMain axis

Claims

1. Device (1) for the production of tube packaging blanks (10) by means of extrusion, the device comprising a die (2), a punch (3) and an ejector (4), wherein the punch (3) has a tool holder section (3.1), a shaft section (3.2) and a punch head (3.3), wherein the die (2) has a die interior (2.4) bounded by a die base (2.1) and a die wall (2.2), wherein the die interior (2.4) forms the negative of the punch head (3.3), including a section of the shaft section (3.2) adjacent to the punch head (3.3) and intended for engagement with the die (2), wherein the die base (2.1) has an opening (7) arranged concentrically with the circumference of the die base (2.1), wherein the ejector (4) engages positively in the opening (7) of the die base (2.1) and closes the opening (7) flush with the die base (2.1), characterised in that the shaft section (3.2) together with the punch head (3.3) is formed in one piece from a material with a Rockwell hardness of at least 60 HRC, wherein the shaft section (3.2) has, at least in its section intended for engagement in the die (2), the shape of a straight circular cylinder with a diameter (d) of at most 10 mm.

2. Device (1) according to claim 1, characterised in that the entire punch (3) with tool holder section (3.1), shaft section (3.2) and punch head (3.3) is formed in one piece from a material with a Rockwell hardness of at least 60 HRC.

3. Device (1) according to claim 1 or 2, characterised in that the material has a Rockwell hardness of at least 63 HRC.

4. Device (1) according to any one of claims 1 to 3, characterised in that the material is steel 1.3343 with a Rockwell hardness of 64 HRC to 66 HRC.

5. Device (1) according to any one of claims 1 to 4, characterised in that the shaft section (3.2) has a diameter (d) of at most 9.8 mm, preferably at most 9.5 mm, and particularly preferably at most 9.2 mm, at least in its section intended for engagement with the die (2).

6. Device (1) according to any one of claims 1 to 5, characterised in that the punch head (3.3) has a spray edge (5) arranged in an area facing the shaft section (3.2) and projecting circumferentially over the entire circumference of the punch head (3.3).

7. Device (1) according to any one of claims 1 to 6, characterised in that the punch head (3.3) has the shape of a torus segment at least in a partial area (3.31) of an area adjacent to the spray edge (5).

8. Device (1) according to claim 7, characterised in that the torus segment is a segment of a torus tube with a radius (R) between 0.1 mm and 30 mm, preferably between 0.5 mm and 10 mm, and particularly preferably between 1 mm and 5 mm.

9. Use of a device (1) according to any one of claims 1 to 8 for the production of tube packaging blanks (10), wherein a diameter (dr) of a tube blank body of the tube packaging blanks (10) is a maximum of 10 mm.

10. Method for the production of a tube packaging blank (10) by extrusion, comprising the steps a) providing a device (1) according to claims 1 to 8, b) inserting a circular blank into the die (2), c) inserting the punch (3) into the die (2) and applying pressure to the circular blank, d) removing the tube packaging blank (10) from the die (2).

11. Method according to claim 10, characterised in that the circular blank consists of aluminium, an aluminium alloy or copper.

12. Method according to claim 10 or 11, characterised in that after step d), the step e) forming an external thread (11) in the area of a tube neck of the tube packaging blank (10) by rolling or squeezing is carried out.

13. Method according to claim 12, characterised in that the external thread (11) is an M7 thread.