CH707820A2 - Method and apparatus for producing aerosol cans, and the can body. - Google Patents

Abstract

For producing aerosol can bodies (10) having a can sheath (12) extending along a can axis from a can bottom (3) to a valve region (9) along the can axis, a preform (6) is stretch blown sleeve-shaped stability element (1) to a stretch blown hollow body (7). The stretch blow-molding step is carried out so that, after the stretch blow-molding step, a region of the outside of the stretch-blown hollow body (7) bears against a region of the inside of the sleeve-shaped stability element (1). In the region of the stability element (1) can be dispensed with inherent stability or dimensional stability of the stretch blown hollow body (7). With the stretch blow molding directly inside the stability element (1), the hollow body (7) obtains the dimensional stability by the abutment against the stability element (1).

Description

The invention relates to a method for producing aerosol can bodies according to the preamble of claim 1, to aerosol can body according to the preamble of claim 11 and to devices for producing aerosol can bodies according to the preamble of claim 12.

Can bodies are formed one or more parts. In one-piece aerosol aluminum cans, a cylindrical can body is provided by cold extrusion. Subsequently, a narrowed neck part is formed at the open end by upset necking. This manufacturing process is very complex due to the required for the many processing steps and the water and energy requirements for cleaning and drying. US Pat. No. 4,095,544 and EP 0 666 124 A1 describe the production of seam-free steel cans. In this case, the cylindrical can body is produced by means of stamping, pressing and ironing out of a tin or plastic-coated steel sheet. When forming a narrowed can neck enormous problems can occur because the material structure is changed by the stretching or hardened. In the known one-piece cans are located on the outside cans fat or oil residues. To form a decorative layer, cleaning (washing, drying), priming (drying), printing and overcoating are performed directly on the vessel outer surface, which is very expensive.

When printing shaped aerosol cans, the printing costs can be of the order of magnitude of the raw can price. Disturbances on the printing press lead to interruptions in can production. Another disadvantage is due to the fact that in the execution of smaller doses orders on the printing press, the printing plates or printing cylinder must be replaced, which leads to the shutdown of the entire can production line. The printing press must be operated and monitored by a printing expert.

For the production of three-piece boxes metal sheets can be printed with grid-shaped decorations and then cut into individual frames are cut, the frames are further processed to can coats.

From WO 05/000 498 a solution is known in which, starting from a metal strip with a forming and a welding step, a circumferentially closed tube is made to be separated from the shell sections for cans. At each closed with a pushed laser longitudinal seam can jacket is attached to the lower end side of a can bottom with a laser seam. At the upper end a constriction is formed. Optionally, the upper end of the can jacket is necked by compression necking or spin-gap necking, which restriction can be performed until the valve seat is formed.

According to WO 2012/135 968 A1 canned shells are produced from flat material areas, which are closed in the circumferential direction with an adhesive bond in an overlapping area for producing a can body with a can jacket extending in the circumferential direction about a can axis and a can bottom. On one end of each can jacket a can bottom is attached.

The cost of a tight connection between the can jacket and bottom of the can can be undesirably large.

Stretch blown aerosol cans made of PET must be made with wall thicknesses or thicknesses in a high range of 2-3 mm in order to reduce the risk of breakage due to embrittlement phenomena sufficiently. The necessary large wall thicknesses of the preforms lead to manufacturing problems. From DE 10 031 136 A1 an aerosol or compressed gas can body made of polyethylene terephthalate (PETP) and / or polyethylene naphthalate (PEN) is known, which is intended to overcome the disadvantages of aerosol cans made of PET. The wall thickness can only be reduced due to the choice of material matched to the product. This solution is therefore neither generally applicable nor simple and safe. In addition, the large differences in the can wall thickness in the direction of the can axis from 0.4 to 1.3 mm, which occur even with this choice of material, show that the plastic material used for the can is not used optimally. The risk of breakage is determined by the areas with minimal wall thicknesses. In areas with higher wall thicknesses material is used ineffective. When comparing the material and production costs between plastic and metal cans, the price shows that the production of the plastic cans involves much more effort.

GB 2 214 891 A shows aerosol cans made of plastic, in which a stretch blown inner container is inserted into at least one outer vessel part made of plastic. In order to enable automated insertion, the stretch-blown inner container must have sufficient intrinsic stability or dimensional stability. The outer vessel part comprises at least one sleeve-shaped portion and is made as a shatter-proof injection molded part of loadable plastic, which is associated with a great effort and high material costs. The sum of the wall thicknesses of the adjacent wall areas of the inner container and the outer vessel portion are relatively large, so that the amount of plastic material necessary for the entire aerosol can is very large. The insertion of the inner container in the at least one outer Gefästeil is complex and can lead to damage. The production cost is even greater if the outer shape of the aerosol can deviates from the cylindrical shape. Then at least two outer vessel parts are pushed together over the inner container.

The present invention has for its object to find a solution with the aerosol cans can be easily and inexpensively manufactured, wherein in addition to the tightness of the can and their appearance should be high quality. The preparation should preferably take place with the greatest possible flexibility and with simple facilities.

The inventive object is achieved by the features of claims 1,11 and 12. The dependent claims describe preferred or alternative embodiments.

With the method according to the invention, the aerosol can bodies according to the invention are produced. The aerosol can bodies include a can jacket extending about a can axis that extends along the can axis about a can height from a can bottom to a valve region. At least in a section of the can height that extends from the bottom of the can, the can jacket has a stability element that encloses a stretch-blown hollow body. The stretch blown step performed on a preform to form the stretch blown hollow body is performed in the stability element. The stretch blow-molding step is performed such that after the stretch blow-molding step, a portion of the outside of the stretch blown hollow body abuts against a portion of the inside of the sleeve-shaped portion of the stability element.

Preferably, the stretch blow is performed in a blow mold, in which the stability element is inserted before the stretch blow.

In the method according to the invention and in aerosol can bodies according to the invention, an inherent stability or dimensional stability of the stretch-blown hollow body can be dispensed with in the region of the stability element. With the stretch blow molding directly inside the stability element of the hollow body receives the dimensional stability by the concern of the stability element. In this area, the variation of the wall thickness is small, so that the stretch blown hollow body comprises substantially no material that is not needed. The stability element is designed to guarantee the necessary stability. Its sleeve-shaped portion can be formed with a substantially constant wall thickness. Preferably, the stability element comprises a closure bottom which forms the bottom of the can.

The stretch blown hollow body has to provide only a dense layer, so that the interior of the aerosol can body is connected only at the valve area with the environment. The valve region is formed on the stretch-blown hollow body and is closed during the completion of the aerosol can with a valve. The stability of the aerosol can body is ensured in the region of the stability element of this. If the stretch-blown hollow body protrudes beyond the stability element with an end region at the valve region, then the projecting end region is formed with a sufficiently high stability or an increased wall thickness, so that the entire can body has the necessary stability.

In the preparation of the aerosol can body, the preform is pre-tempered for the stretch blow, wherein the pre-tempering is preferably carried out prior to the introduction of the preform in the blow mold. Due to the previous tempering, the processing time in the blow mold can be reduced.

The preferred preforms are formed so that the stretch blown hollow body provide a can neck portion at the valve area. If an engagement form for an aerosol can lid is formed on the neck portion, it may be formed so precisely that it cooperates securely with the corresponding engagement shape of the lid. By choosing plastics with similar material properties for the preform and the lid, the security of interaction can be increased even at different temperatures.

In preferred embodiments, the stretch blown hollow body is in front of the valve element on the stability element, wherein there is formed a wall thickness which is at least four times, preferably at least eight times, as large as the wall thickness in a central axis portion of the stability element.

Further preferred preforms are designed so that they provide a valve seat with a precise shape at the valve area. This valve seat is not changed during stretch blow molding, so that even on the finished can body a precisely shaped valve seat is formed, which can be optimally associated with the corresponding connection point of a valve in connection. At valve seats with the form used in the common aerosol cans, the common valves or valve plates can be tightly secured by crimping. But it is also possible that new valves, especially those with a connection area made of plastic, are tightly connected to the valve seat. In addition, latching, screwed, glued or even formed with supplied heat connections in question. By choosing plastics with similar material properties for the preform and the connection area of the valve, a tight connection can be ensured even at different temperatures.

In a further preferred embodiment, the stability element with the sleeve-shaped section comprises a closure bottom which forms the bottom of the can. The stability element with closure bottom is formed as desired in the area near the ground of the aerosol cans. The stretch blown step is performed so that after the stretch blown step, a portion of the outside of the stretch blown hollow body abuts against an area of the inside of the end floor. As a result, substantially the entire area of the hollow body within the stability element is in contact with the stability element. The built-up after filling the aerosol can internal pressure can be taken up accordingly by the stability element.

A particularly complete concern of the stretch blown hollow body on the inside of the stability element is achieved in that the stability element in the transition region from the sleeve-shaped portion to the bottom end passage openings are formed, through which air can escape during stretch blowing.

In a particularly preferred embodiment, the stability element is formed of metal. Compared to plastic, metal has the advantage that even with small wall thicknesses a high degree of stability is achieved and that this stability remains over a wide temperature range. In addition, all known from the prior art can manufacturing can be used for can coats and / or can coats with arranged thereon cans. Because the stability element, the connection from the sleeve-shaped portion to the final floor not dense but only stable, the manufacturing cost of the stability element can be made smaller than for conventional aerosol cans with attached to the wall of the can wall. Due to minimal material quantities and efficient manufacturing processes, stability elements can be produced very efficiently and optimized for their function.

If a decorative layer is formed on the outside of the sleeve-shaped portion of the stability element before insertion into the blow mold, so can be dispensed with the laborious printing of can bodies. This is particularly advantageous when the decorative layer is applied to flat material, which is then converted to the sleeve-shaped portion of the stability element, preferably on the sleeve-shaped portion, a closure bottom is attached. The production of sleeve and / or cup-shaped stability elements, in particular with decor attached to the outside of the sleeve, is particularly efficient with metallic material, preferably flat material or sheet metal.

In preferred embodiments, a cross-sectional constriction is formed on the tubular portion of the stability element in the direction of the can axis from the bottom of the can against the valve region at least in a partial region, preferably in the end region, which faces the valve region. In the case of stability elements made of metal, starting from a cylindrical element with a deformation of the shell or the sleeve-shaped section, the desired shape can be easily formed. In a further simplified solution, the sleeve-shaped portion is pressed directly during stretch blow molding to the blow mold and thereby slightly reshaped.

Besides or instead of the cross-sectional constriction, decorative surface designs or embossings can also be provided. Because the stretch blown step is performed inside the stability member, the abutment of the stretch blown hollow body to a sleeve-shaped portion having strong molding properties can be ensured. Due to the concern with the constriction and / or other design elements deviating from the cylindrical shape, the stretch-blown hollow body is retained in the stability element at least after the build-up of an overpressure inside the can. If this adhesion between the hollow body and the stability element does not suffice for safe keeping together, adhesive may also be applied to a region of the inner side of the stability element before the stretch blow molding.

If the stretch blown hollow body after emptying of the aerosol can again be separated from the stability element, it is advantageous if the adhesion between these two parts in the absence of pressure in the can interior is so small that the stretch blown hollow body can be pulled out of the stability element , With this separation option, the different materials of these parts can be disposed of separately, which is particularly advantageous if the stability element is formed of metal.

The drawings illustrate the inventive solution based on embodiments. Show <Tb> FIG. 1 and 2 <SEP> schematic longitudinal sections through a stability element, <Tb> FIG. 3 and 4 are schematic longitudinal sections through a stretch blow mold with elements of an aerosol can and <Tb> FIG. 5 and 6 <SEP> schematic longitudinal sections through an aerosol can.

1 shows the sleeve-shaped section 2 of a stability element 1. According to FIG. 2, a closure bottom 3 is arranged on the sleeve-shaped section 2 and subsequently fastened. The resulting cup-shaped stability element 1 can be made according to any known from the prior art can manufacturing process manufacturing method for can coats with arranged thereon can floors. The connection from the sleeve-shaped section 2 to the closure bottom 3 does not have to be dense but only stable. In the preferred metal stability elements, for example, a connection with welding points can be provided. In order to allow air to escape during stretch blowing, openings may also be formed at the connection area.

Fig. 3 shows a blow mold 4 with an inner mold 5 in the interior of the stability element 1 is inserted. It goes without saying that the outer shape of the stability element is substantially adapted to the inner mold 5. In addition, a heated preform 6 is introduced into the blow mold 4 and into the stability element 1. In Fig. 4, the end of the Streckblasschritts is shown. In this case, the stability element 1 bears against the inner surface 5 of the blow mold 4. The outside of the stretch blown hollow body 7 abuts against the inside of the stability element 1.

The preform 6 is formed so that it forms a valve region 9 with a valve seat 8 at the open end. This valve seat 8 is not changed during stretch blow molding, so that even on the finished can body 10, a precisely shaped valve seat 8 is formed.

In the illustrated embodiment, the sleeve-shaped portion 2 of the stability element 1 does not extend from the closure bottom 3 to the valve region 9. From the open end of the sleeve-shaped portion 2, the stretch blown hollow body 7 extends as a narrowed neck portion 11 to the valve seat 8. The neck portion 11 has the stretch blown hollow body 7 has a substantially greater wall thickness than in the region with the stability element 1. The sleeve-shaped portion 2 of the stability element 1 is also somewhat narrowed towards the neck portion 11.

Fig. 5 shows the can body 10 with the can bottom formed by the bottom plate 3, the can jacket 12 formed by the stability element 1 and the stretch blown hollow body 7, as well as with the valve area 9. Inside the aerosol can body, a product 13 is filled.

Fig. 6 shows the can body 10 after insertion of the valve 14. The bubbles 15 indicate that even the pressurized gas has been introduced through the valve. At the end, an unillustrated can lid is placed. When an engaging form 16 for the can lid is formed on the neck portion 11, it can be formed so precisely that it cooperates securely with the corresponding engagement shape of the lid.

Claims (12)

A method of manufacturing aerosol can bodies (10) having a can jacket (12) extending about a can axis extending along the can axis over a can height from a can bottom (3) to a valve region (9), the can shell (12) at least a stability element (1) having a sleeve-shaped section (2) enclosing a stretch-blown hollow body (7) in a section of the can body height starting from the can bottom (3), the access opening to the interior of the stretch-blown hollow body (7) enclosing the valve region (9) characterized in that the stretch blown step performed on a preform (6) for forming the stretch blown hollow body (7) is performed in the stability element (1), wherein the stretch blow step is performed so that after the stretch blow step, a portion of the outside of the stretch blown hollow body (FIG. 7) at an area of the inside of the sleeve-shaped portion (2) of the Stabilit tselements (1) is applied. 2. The method according to claim 1, characterized in that the stretch blow molding step for forming the stretch blown hollow body (7) in a blow mold (4) is performed, in which before the stretch blow the stability element is inserted, preferably the preform (6) for the stretch blow preheating is carried out and the preheating is carried out before the introduction of the preform (6) in the blow mold (4). 3. The method according to claim 1 or 2, characterized in that the stability element (1) with the sleeve-shaped portion (2) comprises a closure bottom (3) and that the stretch blow is performed so that after the stretch blown step, a portion of the outside of the stretch blown hollow body (7) abuts an area of the inside of the end floor (3), wherein the end floor (3) forms the bottom of the can (3). 4. The method according to claim 3, characterized in that the stability element (1) in the transition region from the sleeve-shaped portion (2) to the closure bottom (3) comprises passage openings, and the outside of the stretch blown hollow body (7) after the stretch blow substantially on the entire inner side of the stability element (1) is applied. 5. The method according to any one of claims 1 to 4, characterized in that the stability element (1) is formed of metal. 6. The method according to any one of claims 1 to 5, characterized in that on the outside of the sleeve-shaped portion (2) of the stability element (1) already before performing the Streckblasschritts a decorative layer is formed. 7. The method according to claim 6, characterized in that the decorative layer is applied to flat material, which is then reshaped to the sleeve-shaped portion (2) of the stability element (1) and that preferably on the sleeve-shaped portion (2) a closure bottom (3) is attached. 8. The method according to any one of claims 1 to 7, characterized in that on the sleeve-shaped portion (2) of the stability element (1) in the direction of the can axis from the bottom of the can against the valve region (9) towards at least in a partial region a cross-sectional constriction is formed, preferably in End portion facing the valve portion (9). 9. The method according to any one of claims 1 to 8, characterized in that the stretch blown hollow body (7) at the valve region (9) via the stability element (1) protrudes and there is a wall thickness formed at least four times, preferably at least eight times, so large is like the wall thickness in a central axis section of the stability element (1). 10. The method according to claim 9, characterized in that the stretch blown hollow body (7) at the valve region (9) comprises a valve seat (8), which is preferably already formed during the production of the preform, and that the stretch blown hollow body (7) has a constricted Neck part (11) and in particular an engagement form (16) for an aerosol can lid. An aerosol can body (10) having a can jacket (12) extending about a can axis extending along the can axis over a can height from a can bottom (3) to a valve region (9), the can mantle (12) at least in one from the can bottom (3) outgoing section of the can height has a stability element (1) with a sleeve-shaped portion (2) which encloses a stretch blown hollow body (7), wherein the access opening to the interior of the stretch blown hollow body (7) forms the valve region (9), characterized in that the stretch-blown hollow body (7) is shaped from a preform (6) by means of a stretch blow-in step in the stability element (1) with a sleeve-shaped section (2) and an area of the outside of the stretch-blown hollow body (7) at an area of the inside of the sleeve-shaped section (2) of the stability element (1) is applied. 12. An apparatus for producing an aerosol can body, characterized in that the device makes a method according to one of claims 1 to 10 feasible.