FORMING SET FOR A SKI PRESS

Description

Field of invention

[0001] The novel manufacturing concept for skis enables serial, industrial production with a batch size of 1. State of the art

[0002] AT 11 913 U1 discloses a device for pressing skis, in particular for gluing.

[0003] With current technology, skis can only be manufactured efficiently if a single model is produced continuously in large quantities. Changing the model is complex and involves long setup times and costs. Furthermore, current processes are optimized for maximum throughput, which can be detrimental to the actual, optimal production of skis. The present concept rearranges the levels (heat, pressure, shaping) of a ski production unit, incorporates new technologies, and restructures the production process. This results in a novel manufacturing process for skis that is superior to the current state of the art in terms of setup times, mold costs, handling, and composite material bonding. For the first time, this new process makes efficient, serial production with a batch size of one possible.

[0004] The term "ski" is used synonymously for any type of snow gliding board, e.g., alpine skis, touring skis, jumping skis, cross-country skis, monoskis, or snowboards. The term "ski" will be used consistently throughout this text.

[0005] Skis are fiber composite materials, manufactured by bonding different materials together. The bonding process is typically carried out using a combined method of pressure and temperature.

[0006] The shape and function of a ski is defined by the outer contour, also called sidecut, the vertical contour, also called vertical contour, the nose line, also called camber or camber line, and the construction, i.e., the different materials, material thicknesses and arrangement of the different materials.

[0007] In the so-called sandwich process, the necessary components are layered on top of each other and then bonded together with or without heat and under varying pressures. This process was patented by Charles R. Hale in 1980 (Hale et al., 1980). Examples of this process come from companies such as Stöckli and Atomic.

[0008] In the first step, the components necessary for the ski are glued together, usually with epoxy resin, and layered on top of each other. As an alternative to gluing with liquid adhesive, pre-impregnated layers, so-called prepregs, or adhesive films can also be used. These usually liquefy at higher temperatures and create a bond with the layers above and below.

[0009] In industrial processes, this layered structure is typically created in rigid molds made of aluminum, steel, or similar materials. In this ski-shaped mold, all components are usually placed into a lower mold section. After all components are inserted, the mold is closed with an upper mold section or a simple lid. The ski mold primarily defines the outer contour of the ski.

[0010] In handcrafted ski manufacturing, rigid molds are often dispensed with. When skis are manufactured without molds, the components are contoured and temporarily fixed in place. Typically, for example, the steel edges are fixed to a contoured base using superglue. The layers above are then applied, sometimes with an oversize. Often, the bottom layer, consisting of the base and steel edges, later serves as a contour guide for cutting out the finished, pressed ski. A disadvantage of this method is the lack of precise reproducibility with the quality tolerances of industrial molding processes. This handcrafted assembly is placed on a flat, rigid base that defines the ski's shape. The top layer is usually a flat, rigid sheet made of wood, aluminum, or a similar material.

[0011] Pressure is applied to this unit, consisting of the mold or base / lid and the ski materials sandwiched between them, usually, but not necessarily, in combination with temperature. In industrial processes, this pressure is primarily generated by a press. The pressure is applied mechanically in the press process; the level depends on the material, construction, adhesive system, and other parameters. It typically ranges between two and twelve bar. In handcrafted processes, pressure is sometimes generated by creating a vacuum. In the vacuum process, the assembled ski is hermetically sealed with a bag or film, and a vacuum pump is used to create a vacuum. (Marmota Magazine, 2018) The resulting pressure in this process is theoretically a maximum of one bar, but in practice, it is usually slightly less.Another possibility is that the pressure is generated by filling hoses within a fixed frame, usually pneumatically.

[0012] The ski's vertical contour is created using a sandwich construction process by contouring the ski components. Different layer thicknesses and a defined layer structure determine the vertical contour, or ridge, along the ski's longitudinal axis. The pressing process aims to generate the most uniform pressure possible on the ski's vertical contour to achieve optimal, consistent bonding despite varying component thicknesses.

[0013] The ski's nose line creates the geometric shape of the contact surface. This can be defined by the ski's shape itself, usually in combination with a molded base, and sometimes also by a top section. Both top and bottom sections are primarily used in industrial production. In handcrafted production, the top section is sometimes omitted, particularly in vacuum forming processes.

[0014] When an industrial press is used, the upper and lower structures are generally permanently or at least firmly connected to the press. They form a die system that distributes pressure onto the ski shape through contour and counter-contour. The aim is to precisely produce the ski's contour and to distribute temperature and pressure onto the workpiece to be bonded in such a way as to achieve optimal and uniform adhesion.

[0015] The upper and lower sections of a ski are always designed for a specific ski model, meaning a particular ski length and nose profile. Changing ski models therefore always involves changing or adjusting the upper and lower sections. Common methods include the use of fixed die systems made from solid wooden blocks or other rigid and stable materials, or, especially in industrial applications, adjustable die systems. These systems offer manual adjustment of the nose profile via adjusting screws or sawtooth profiles, or automatic adjustment via CNC controls.

[0016] When thermal compression is applied, a heating element, sometimes combined with a cooling element, is located on the plane between the ski shape and the upper or lower structure. The heating element can take various forms, with aluminum heating plates or electric heating mats being the most common methods.

[0017] A modern ski press regulates the optimal pressing and bonding of the ski via the pressure curve, the time, and the heating and cooling cycle.

[0018] A ski press therefore consists of four essential components: the press, an upper and lower structure, the actual ski shape, and optional heating and cooling systems.

[0019] Serial ski production currently works as follows: 1. The ski itself is placed in individual parts into a mold outside the ski press. 2. This mold is inserted into an upper and lower structure already installed in the press. If an additional heating and cooling layer is present, these are also pre-installed in the press. 3. The ski is pressed under pressure and elevated temperature and usually cooled again in the mold. 4. The press is then opened, the mold removed, and the ski demolded. 5. Simultaneously, another ski is assembled outside the press in additional, redundant mold sets and then inserted into the press. If no redundant mold sets are available, the single mold is demolded, cleaned, and the process begins again. In this case, the press remains stationary during these latter steps.

[0020] The advantages of "state of the art" production are high speed and accurate reproducibility, making it ideal for large batch sizes.

[0021] However, such systems also have disadvantages. To change the model or length, the upper and lower structures must be changed or adjusted, which is very complex with this system and involves setup time and corresponding costs. Furthermore, several mold sets are required per model to enable high-speed serial production. This results in high mold costs. Especially with high-temperature pressing processes, the components used in the ski are heated to critical limits of their load-bearing capacity. This system is widespread in industrial ski manufacturing. A processing temperature range of 90–140° Celsius is typically specified. This temperature is borderline close to or above the typical Vicat softening temperatures (VST) of some materials used for ski bases, for example, 128° Celsius. Typical problems such as sink marks on ski bases are known defect patterns in industrial manufacturing.No statements from the industry regarding this well-known problem can be found.

[0022] High-temperature curing of epoxy resins (high temperature, short curing time) results in almost 100% cross-linking and thus optimal temperature and humidity resistance, adhesive strength, and chemical resistance, as well as minimal outgassing rates. However, such processes also make the adhesives extremely brittle. To achieve the desired properties of high-temperature curing without its drawbacks, it is recommended to increase the curing temperature slowly, e.g., 10°C / 5 min, and then cool it down slowly as well. This reduces thermal stress. However, such a process would undesirably increase the cycle time in state-of-the-art industrial ski production.

[0023] Another disadvantage is that the materials commonly used in ski construction (steel edges, plastics, wood, aluminum, etc.) exhibit significantly different thermal stresses. To avoid these disadvantages, Fischer Sports recently developed a process for cross-country skiing in which the base is applied to the ski body after the fact, without heat or pressure (EP 2928570). The patent specification cites the avoidance of unwanted thermal stresses, particularly with regard to the polyethylene bases used, as an advantage. The company's marketing materials also describe the advantages as "unrivaled wax absorption and ease of sharpening." However, such a process is only suitable for the production of cross-country skis, as these are subject to lower mechanical stresses than alpine skis.

[0024] The cooling process primarily serves to achieve a fast overall cycle time, but it is not entirely beneficial for the curing of the composite component. Rapid cooling creates stresses within the component or fixes existing stresses.

[0025] Heat and pressure can only be generated while the ski mold is inserted into the press. A resulting disadvantage is that it is not possible to insert pre-tempered components into a pre-tempered mold. Furthermore, tempering in the physical sense cannot be achieved, since the possibility of controlled heating is lost when the ski mold is removed from the press. If tempering were to occur within the press, however, an undesirably long cycle time would result. Description of the invention

[0026] The task is to avoid the aforementioned disadvantages.

[0027] A mold assembly according to the invention for insertion into and removal from a ski press comprises a substructure having a base plate, a lower contour and a lower heating element; and a superstructure having a top plate, a top contour, and an upper heating element, so that a ski mold can be inserted between the substructure and the superstructure outside the ski press.

[0028] Preferably, the superstructure also includes steel profiles for pressure distribution, in particular transverse, chain-like arranged steel profiles.

[0029] Furthermore, the superstructure preferably also features an elastic compensating element.

[0030] In another embodiment, the superstructure can be attached to the cover plate (16) by means of tension springs (14).

[0031] The mold assembly may preferably include uprights and compression springs arranged on the uprights to keep the mold assembly open.

[0032] A ski press according to the invention comprises the aforementioned forming assembly. In particular, the ski press includes positioning aids designed to fix the forming assembly in the ski press.

[0033] In this newly developed concept, the ski press is reduced to its function as a printing press. A mold assembly, consisting of the actual ski mold, its corresponding upper and lower sections, and the heating elements between them, is inserted into this "open / close" press. During production, the ski is first placed into the ski mold outside the press; this is then placed into the matching upper and lower sections in a second step. These sections already contain the heating and cooling elements, meaning that certain desired heating or cooling cycles can also be carried out outside the press (before and / or after the printing cycle). This three-element assembly is then placed into the press. While one assembly is in the press, the next model can already be prepared.Once the printing cycle is complete, the entire press assembly is pushed out of the press, and the next prepared assembly can be inserted immediately for the next printing cycle. This reduces the press setup time to just a few seconds for inserting and removing the assemblies. The greatest advantage of this concept is that model changes occur without any setup time. A ski of model XY with a length of 175 cm can be produced directly after model YX with a length of 151 cm. Conventional methods always require approximately 30 minutes of setup time for a model or length change. The technically necessary printing cycle can thus be utilized to its maximum extent. Press downtime due to changeover processes is reduced to the absolute minimum. Another advantage is that the mold assembly can also be heated or cooled in a controlled manner before or after the actual pressing process.Post-tempering can be used to achieve desired component effects or changes, and in particular to optimally compensate for thermal stresses. Brief description of the characters

[0034] Figure 1 shows a cross-section through a mold set in a ski press; and Figure 2 demonstrates a turret method using the mold set made of Figure 1 . Description of the preferred embodiment

[0035] The concept is realized with a system consisting of a ski press 2 which uses a piston 1 to move a pressure beam 3 against a fixed beam, thereby exerting pressure. Alternatively, the pressure can also be generated by other known methods, such as a pressure hose. The novel system, consisting of a unit comprising upper and lower molds, heating elements, and the actual ski mold, is inserted into this press.

[0036] In Figure 1The mold block is shown in a ski press 2. The individual components are the piston of the press 1, the ski press 2, the pressure beam 3 of the press, the base plate 4 of the mold block, the lower contour 5 of the mold block, the positioning aids 6, the lower heating element 7, the compression spring 8, the support beam 9, the aluminum ski mold 10, the upper heating element 11, the steel profiles 12 for pressure distribution, the elastic compensating element 13, the tension spring 14 to hold the upper part of the mold block in place, the upper contour 15 of the mold block, and the top plate 16 of the mold block.

[0037] The lower part of the unit consists of the base plate of the mold block 4, the lower contour of the wooden mold block 5, and the lower heating element 7. Compression springs 8 and support beams 9 hold the system open. The ski mold itself 10 is located in the center of the unit. The upper part of the unit comprises the upper heating element 11, the steel profiles for pressure distribution 12, an elastic compensating element 13, and the upper contour of the wooden mold block 15. This is held to the top plate 16 by tension springs 14. Thanks to the spring support, the upper part of the unit can be easily operated by hand, without the need for additional tools. The ski mold 10 can then be easily filled and inserted into the system.

[0038] Positioning aids 6 fix and anchor the mold within the system. Once the mold is fixed, the entire system is positively locked in place and inserted into the press using positioning aids 6. Due to the considerable weight of the mold systems, they are moved on roller systems, by robots, or by an overhead crane. The press is then closed, and the ski is pressed. Since the press can easily overcome the spring force of the compression springs, these do not negatively affect the process, and any necessary pressure equalization can be easily calculated. The entire system can then be removed, and the next mold block can be inserted. Using a turret system, different skis can thus be produced serially in batch size 1.

[0039] In industry standard practice, ski presses are typically loaded and set up from one side using the methods described above. In this case, a rotating system is to be used to load the press from one side and unload it from the other side using a push-through system. This rotating system is in Figure 2 visible. Figure 2Step (A) shows the loading of the mold block, step (B) the preheating of the mold block, step (C) the mold block in the press, step (D) the post-tempering of the mold block, and step (E) the demolding of the skis. In position (A), the units are loaded outside the press, ideally near a component storage area. Here, the individual ski parts are assembled in the ski mold, and the ski mold is then inserted into the unit. In position (B), if desired, the entire unit can be heated starting at this loading step. In position (C), the unit is inserted into the actual press as described above. After pressing, the innovative unit can be post-tempered in position (D) if desired. Subsequently, the ski mold is removed in position (E), and the skis are demolded.

[0040] The inventive method for manufacturing skis relates to a rearrangement of the system components by combining the upper and lower structure, heating layer and ski shape into a single unit with the following advantages: a) Minimizing setup times or shifting setup times away from the press. The actual press setup is limited to loading and unloading the unit. This drastically reduces setup times at the press and thus represents maximum possible press utilization. b) The press cycle time is therefore no longer dependent on the number of mold sets available. This results in cost reduction, as multiple mold sets no longer need to be produced to optimally utilize the press.

[0041] The self-supporting system using uprights and springs has the following advantages: a) This facilitates the handling of the very heavy mold superstructure and upper heating element. The high weight of these components means that, in the prior art, they always have to be rigidly connected to the press, which makes the prior art heavier to handle, more complicated to fix, and slower in terms of setup times compared to the system according to the invention.

[0042] The option of pre- and post-tempering has the following advantages: a) The rearrangement of the heating element within the system, or rather the combination of the heating element with the ski mold in the unit, made it possible to temper the actual ski mold independently of the insertion time in the press or the printing cycle. This would otherwise only be possible with combined heating / molding tools. While such heated molds are known from other industries, they are not widely used in the ski industry. The manufacturing costs of such heated molds are many times higher than those of the inventive combination of an unheated ski mold with heating elements positioned above and below it. The rearrangement of the system components thus represents the only way in which comparatively inexpensive ski molds can be tempered outside of the ski press.b) The disadvantages of designing the heating cycle for an optimal press cycle time are eliminated; this means the heating cycle can be designed and optimized independently of the pressure cycle, which offers advantages in terms of compensating for structural defects, improving and eliminating unwanted stresses / thermal stresses and component distortion.

[0043] The turret system according to the invention differs from the prior art, i.e., from known systems that combine forming, heating, and cooling in a single tool. These existing movable tools are expensive, highly complex, and integrated metal tools. The approach presented here combines a forming plane, which is simpler and more cost-effective to manufacture than heated tools, with a heating plane. This system offers the same advantages with regard to thermal tempering as the known, more expensive, and more complex systems. Compared to the known industrial process of ski manufacturing, however, it offers the advantage of enabling serial, single-item production according to the assembly line principle. This results in simple and efficient production logistics with comparatively low acquisition costs for the necessary tools and system components.

[0044] The mold assembly according to the invention can also have hydraulic cylinders instead of the compression springs 8 and the support beam 9. These cylinders are attached to the base plate 4 and the cover plate 16 and serve to press the base plate 4 and the cover plate 16 together. The hydraulic cylinders thus operate as tension cylinders.

Claims

1. Mold set for insertion into and removing out of a ski press (2) comprising: a lower structure having a base plate (4), a lower contour (5) and a lower heating element (7); and an upper structure having a cover plate (16), an upper contour (15) and an upper heating element, so that a ski mold outside of the ski press can be inserted between the lower structure and the upper structure.

2. Mold set according to claim 1, wherein the upper structure further comprises steel profiles (12) for pressure distribution.

3. Mold set according to one of the preceding claims, in which the upper structure further comprises an elastic compensating element (13).

4. Mold set according to one of the preceding claims, in which the upper structure is attached to the cover plate (16) by means of tension springs (14).

5. Mold set according to one of the preceding claims, further comprising stand bars (9) and compression springs (8) which are arranged on the stand bars (9) and hold the molded fitting open.

6. Ski press (2), comprising a mold set according to one of the preceding claims, further comprising positioning aids (6) which are configured to fix the mold set in the ski press.

7. Revolver method for ski production using a molding block according to one of the preceding claims, comprising the steps: - equipping the mold block (A); - introducing the molding block into the ski press and pressing the molding block (C); and - removing the molding block from the ski press and demolding of the ski (E), wherein the steps (A, C, E) are carried out simultaneously on different mold blocks.

8. Revolver method according to claim 7, in which, before the mold block is introduced into the ski press, the mold block is preheated (B), and / or before the skis are removed from the mold, the mold block is post-tempered (D).