METHOD FOR MANUFACTURING A LOW-STEEMGE BELL

Description

[0001] The present invention relates to a method for manufacturing a bellows with a low overall height according to claim 1 and a bellows with a low overall height according to claim 8.

[0002] Nowadays, seats, and especially driver's seats, for vehicles such as cars, trucks, buses, and the like are known to have a massage function. The massage function can be provided by the seat itself. Alternatively, a so-called massage seat cushion can be placed on the seat.

[0003] In both cases, the massage function is achieved by incorporating polyurethane (PU) mats with welded-on bellows, either in the seat cushion or in the massage seat pad. The bellows typically point perpendicularly away from the PU mat and can be pressurized with air. Increasing the air pressure allows the bellows to exert a force on, for example, the back of the person using the seat. Reducing the air pressure causes the bellows to return to their flatter, i.e., normal, position.

[0004] These types of bellows are typically manufactured by punching out individual sections from a sheet of film and then welding them together. Using film has the advantage of allowing for very thin bellows walls. This is particularly beneficial in this application because the bellows must be able to expand significantly in the longitudinal direction perpendicular to the PU mat, reaching a height of, for example, approximately 50 mm, and then contract back down to a height of approximately 8 mm in their normal state. This low height of approximately 8 mm in the contracted state necessitates the use of thin-walled folds, as this minimal height of the bellows would otherwise be impossible to achieve.

[0005] A disadvantage of manufacturing such bellows from welded foils is that the production steps of punching out the foil sections as ring discs and as discs for the end face, and then welding the sections together to form the bellows, are complex. This can result in considerable costs.

[0006] Another disadvantage is that this manufacturing method is prone to errors, as leaks in the bellows can occur if the welds are not executed correctly. Faulty welds can be exacerbated by the small dimensions and thin wall thickness of the film sections.

[0007] A further disadvantage is that bellows manufactured in this way may tend to form deformations and / or indentations when inflated, since the three-dimensional contour of the finished bellows cannot be adequately formed by punching out two-dimensional sections from foil and welding them together.

[0008] A further disadvantage is that the films used are usually smooth and purely two-dimensional. Therefore, welding together sections of film only allows the creation of bellows with smooth outer and inner surfaces. This limits the design of bellows for such applications to those with smooth outer and inner surfaces.

[0009] JP H03 199036 A relates to a method for manufacturing a bellows according to the preamble of claim 1 and a bellows according to the preamble of claim 8. In this method, a longer version of the bellows is first created, which is then compressed to a shorter length. The bellows is then heat-treated.

[0010] EP 2735420 A1 discloses an injection mold suitable for the production of a bellows.

[0011] One object of the present invention is to provide a bellows of the type described above which can be manufactured more simply, quickly, cost-effectively, safely, and / or in more versatile ways than previously known. At the very least, it should provide an alternative to known low-profile bellows.

[0012] The object of the invention is achieved by a method for manufacturing a bellows with a low profile having the features of claim 1 and by a bellows with a low profile having the features of claim 8. Advantageous embodiments are described in the dependent claims.

[0013] The present invention therefore relates to a method for manufacturing a bellows with a low profile suitable for use in a seat with massage function and / or in a massage seat cushion, comprising at least the following steps: Forming the bellows by means of an injection molding process with a first height, reducing the bellows to a second height which is less than the first height, and heat-treating, preferably tempering, the bellows. The first height corresponds to an inflated bellows, and the second height to an unloaded bellows. The bellows is formed using an injection mold, creating at least a raised section and / or a recessed area on the inside and / or outside of the bellows. This allows for at least partial spacing of the facing sides of the folds or ring discs of the bellows, preventing them from touching, which could otherwise lead to sticking and / or noise when separating. This could impair functionality, or the noise could irritate or disturb the user.

[0014] The present invention is based on the finding that a bellows can first be manufactured in one piece at an extended length using an injection molding process, thus enabling the use of this proven, well-known, and cost-effective method for producing the bellows. The folds or ring discs of the bellows can slide over the mold core, i.e., the inner shape of the injection mold, during the extension process, allowing the bellows to be easily removed from the mold.

[0015] The bellows can then be heat-treated at the reduced height it will later exhibit in its contracted, normal state during operation. This allows the bellows to be fixed at this second height as its final installation height. This enables the production of a bellows whose second height is too low to be directly manufactured using an injection molding process. Compared to the previously known method of cutting and welding together sections from foil, this can result in significant time savings and a simplification of the manufacturing process.

[0016] Another advantage is that the susceptibility to defects of bellows, which are made from welded-together sections of foil, can be completely eliminated, since welding can be dispensed with.

[0017] Another advantage is that the three-dimensional contour of the bellows can also be manufactured three-dimensionally. This can prevent deformations and / or sink marks, such as those that can occur in welded two-dimensional sections made of foil.

[0018] A further advantage is that injection molding, using a suitable mold or tool, allows for the creation of three-dimensional designs for the bellows and its surfaces, which is not possible when using sections of two-dimensional film. Therefore, a bellows manufactured using injection molding can be designed in a much wider variety of ways than bellows known to date.

[0019] According to one aspect of the present invention, the bellows is molded from a thermoplastic material, preferably a thermoplastic polyurethane. This makes it possible to mold the bellows to a first greater height using an injection molding process and then to bring it down to its final, unloaded, lower height and thermally fix it at this height.

[0020] According to a further aspect of the present invention, the step of reducing the bellows to the second height is achieved by arranging the bellows between at least two limiting elements. This allows the adjustment of the second, lower height during heat treatment to be carried out in a simple manner. In particular, this fixing can be performed and released easily and quickly, which can minimize the time required for this step.

[0021] According to a further aspect of the present invention, the bellows is arranged between at least two pre-formed rigid plates. This allows the aforementioned fixing to be implemented simply.

[0022] According to a further aspect of the present invention, the inner and / or outer surface of the bellows has at least one projection, preferably a plurality of projections, at least in sections, which is designed as a rib, preferably as a radial rib. This allows for the prevention of contact and / or the discharge of air between the folds or annular discs of the bellows over a greater distance. The radial rib design allows the air between the folds or annular discs of the bellows to be discharged to the outside, in order to prevent noise in particular. The effect of the ribs can be adapted to the specific application by adjusting the number, shape, and / or arrangement of them.

[0023] According to a further aspect of the present invention, the inner and / or outer surface of the bellows has at least one, preferably a plurality of, raised areas, at least partially, which are shaped as hemispheres. This allows raised areas to be formed with very simple geometric shapes in order to achieve point spacing of the folds or the ring discs of the bellows. The effect of these hemispheres can be adapted to the specific application by adjusting the number, shape, and / or arrangement of them.

[0024] According to a further aspect of the present invention, at least one raised area and / or at least one recessed area is arranged on the annular discs of the bellows and / or on the end face of the bellows. By arranging them on the folds or on the annular discs, contact can be avoided there, as previously described. By arranging them on the end face, the contact area can be influenced, for example, towards a user, so that, for example, a massage function can be influenced.

[0025] The present invention also relates to a low-profile bellows suitable for use in a seat with a massage function and / or in a massage seat cushion. The bellows is formed by injection molding to a first height, reduced to a second height which is less than the first height, and heat-treated, preferably tempered, wherein the first height corresponds to an inflated bellows and the second height to an unloaded bellows. The inner and / or outer surface of the bellows has at least one raised area and / or at least one recessed area, at least in some sections. The previously described method according to the invention can preferably be used as such a method. The advantages in this respect have already been described in connection with the method according to the invention and will not be repeated here.

[0026] According to a further aspect of the present invention, the bellows was formed from a thermoplastic material, preferably a thermoplastic polyurethane. The advantages in this respect have already been described in connection with the method according to the invention and will not be repeated here.

[0027] According to a further aspect of the present invention, the inner and / or outer surface of the bellows has at least a portion of at least one projection, preferably a plurality of projections, which is designed as a rib, preferably as a radial rib. The advantages in this respect have already been described in connection with the method according to the invention and will not be repeated here.

[0028] According to a further aspect of the present invention, the inner and / or outer surface of the bellows has at least one projection, preferably a plurality of projections, at least partially, which is shaped as a hemisphere. The advantages in this respect have already been described in connection with the method according to the invention and will not be repeated here.

[0029] According to a further aspect of the present invention, at least one raised area and / or at least one recessed area is arranged on the annular discs of the bellows and / or on the end face of the bellows. The advantages in this respect have already been described in connection with the method according to the invention and will not be repeated here.

[0030] An exemplary embodiment and further advantages of the invention are explained below in connection with the following figures. These show: Figure 1 is a schematic sectional view of an injection molding tool according to the invention; Figure 2 is a schematic sectional view of a bellows according to the invention at a first height; Figure 3 is a schematic sectional view of the bellows according to the invention in a heat treatment tool at a second height; and Figure 4 is a flowchart of a method according to the invention.

[0031] The above figures are described in cylindrical coordinates with a vertical direction Z, which can also be called height Z. A radial direction R extends perpendicular to the axis of the vertical direction Z.

[0032] Figure 1Figure 1 shows a schematic sectional view of an injection mold 2 according to the invention, which has an inner mold 20 at the bottom, which can also be referred to as the mold core 20. At the top, the injection mold 2 has a first outer mold 21 and a second outer mold 22, which enclose the inner mold 20 such that a cavity is formed between the inner surfaces of the outer molds 21, 22 and the outer surface of the inner mold 20. A thermoplastic polyurethane can be injected into this cavity as injection molding material via a filling opening (not shown) to form a bellows 1 with a first height H1.

[0033] Figure 2 Figure 1 shows a schematic sectional view of a bellows 1 according to the invention at a first height H1, as produced using the injection mold 2 of the Figure 1The bellows 1 can be formed. The bellows body 10 has, viewed from top to bottom, an end face 12, to which a plurality of folds extend downwards, formed by annular discs 11. The lowest annular disc 11 adjoins a horizontally oriented base surface 13, which can also be referred to as a mounting ring 13. The end face 12 has an inner surface 12a facing downwards and an outer surface 12b facing upwards. The annular discs 11 have an inner surface 11a facing inwards and an outer surface 11b facing outwards.

[0034] Optionally, for example, projections 14, e.g., in the form of radial ribs 14 and / or hemispheres 14, can be arranged on the outer surface 11b of the ring discs 11. These projections can be formed by corresponding recesses 24 in the outer shapes 21, 22 of the injection mold 2. Also optionally, alternatively or additionally, recesses 15, e.g., in the form of grooves 15, can be arranged on the outer surface 11b of the ring discs 11. These recesses can be formed by corresponding projections 25 in the outer shapes 21, 22 of the injection mold 2. This can prevent or at least reduce contact between the facing ring discs 11, or with the end face 12 and / or the base surface 13, in order to avoid or at least reduce noise caused by such contact. For this purpose, the projections 14 and / or recesses 15 could be arranged on the inner surface 11a of the ring discs 11.

[0035] Optionally, such protrusions 14 and / or depressions 15 can alternatively or additionally be arranged on the outer surface 12b of the front surface 12 (not shown). This can, for example, influence the effect of the outer surface 12a of the front surface 12 when used in a seat with a massage function and / or a massage seat cushion. For this purpose, the protrusions 14 and / or depressions 15 could be arranged on the inner surface 12a of the front surface 12.

[0036] Figure 3 Figure 1 shows a schematic sectional view of the bellows 1 according to the invention in a heat treatment tool 3 at a second height H2. In this view, the bellows 1, which is in the injection mold 2 of the Figure 1 as in Figure 2The bellows 1, as shown, are clamped between a first limiting element 30 and a second limiting element 31 of the heat treatment tool 3 at a height H2, which is less than the first height H1 with which the bellows 1 was produced in the injection mold 2. The two limiting elements 30, 31 are designed as plates 30, 31. In this arrangement of the Figure 3 The bellows 1 is heat-treated by tempering, so that the material of the bellows 1 is fixed at the second height H2. The second height H2 thereby becomes the structural height H2 of the bellows 1, i.e., the height H2 in the unloaded normal state of the bellows 1.

[0037] According to the invention, a bellows 1 can be produced by injection molding with a first height H1, but the finished bellows 1 can be made comparatively flat or with a comparatively low height H2 by tempering at the second, lower height H2. This can be advantageous, for example, for applications such as a seat with a massage function and / or a massage seat cushion.

[0038] Figure 4 Figure 1 shows a flowchart of a method according to the invention. In a first step 100, the bellows 1 is produced in the injection mold 2 by means of an injection molding process according to the Figure 1 formed with the first height H1, as in the Figure 2As shown. Subsequently, in a second step, the bellows 1 is reduced to the second height H2, which is lower than the first height H1. This is done by positioning it between the two plates 30, 31 of the heat treatment tool 3, as shown in the Figure 3 As shown, in this arrangement, the third step 300 involves heat treatment in the form of tempering the bellows 1, so that the shape of the bellows 1 at the second, lower height H2 is fixed as the standard height H2 of the bellows 1. The tempered bellows 1 exhibits a significant restoring force, which tends to return it, particularly at height Z, to this standard state with the standard height H2.

[0039] The present invention is generally applicable to cushions and bellows that are to be deformed, for example, by air pressure. However, the present invention is particularly suitable for bellows 1 with a low overall height H2. Reference symbol list (part of the description)

[0040] H1 First height in the vertical direction Z H2 Second height or building height in the vertical direction Z Radial direction Z Vertical direction; height 1 Bellows 10 Bellows body 11 Ring discs 11a Inner side of ring discs 11 11b Outer side of ring discs 11 12 End face; end face 12a Inner side of end face 12 12b Outer side of end face 12 13 Bottom surface; mounting ring 14 Raised; (radial) rib; hemisphere 15 Recess; groove 2 Injection mold 20 Inner mold 21 First outer mold 22 Second outer mold 24 Recess for forming a raised area 14 25 Raised area for forming a recess 15 3 Heat treatment tool 30 First boundary element or first plate 31 Second boundary element or second plate 100 Molding of the bellows 1 using injection molding with first height H1 200 Reducing of the bellows 1 to second height H2 300 Heat treating or tempering of the bellows 1

Claims

1. Method for making a bellows (1) with a low overall height (H2) suitable for use with a seat with a massage function and / or with a massage seat support with at least the following steps: • forming (100) of the bellows (1) by means of an injection moulding process with a first height (H1), • Reduce (200) of the bellows (1) to a second height (H2) which is less than the first height (H1), and • heat treating (300), preferably annealing (300), bellows (1), wherein the first height (H1) corresponds to an inflated bellows (1) and the second height (H2) to an unloaded bellows (2), characterized in that the step of shaping (100) of the bellows (1) is carried out with an injection moulding tool (2) so that on the inside (11a, 12a) and / or on the outside (11b, 12b) of the bellows (1) at least one elevation (14) and / or at least one depression (15) is formed, at least in sections.

2. The method of claim 1, characterized in that the bellows (1) is formed from a thermoplastic material, preferably a thermoplastic polyurethane.

3. The method of claim 1 or 2, characterized in that the step of reducing (200) the bellows (1) to the second height (H2) is carried out by placing the bellows (1) between at least two boundaryelements (30, 31).

4. The method of claim 3, characterized in that the bellows (1) is arranged between at least two deformation-resistant plates (30, 31).

5. method according to any one of claims 1 to 4, characterised in that the inside (11a, 12a) and / or the outside (11b, 12b) of the bellows (1) has at least one elevation (14) in sections, preferably a plurality of protrusions (14), which is formed as a rib (15), preferably as a radial rib (15).

6. method according to any one of claims 1 to 5, characterised in that the inside (11a, 12a) and / or the outside (11b, 12b) of the bellows (1) has at least one elevation (14) in sections, preferably a plurality of protrusions (14), which is formed as a hemisphere (14).

7. method according to any one of claims 1 to 6, characterised in that which is arranged at least one elevation (14) and / or at least one depression (15) at the annular discs (11) of the bellows (1) and / or at the end surface (12) of the bellows (1).

8. Bellows (1) with low overall height (H2) suitable for use with a seat with massage function and / or with a massage seat support, wherein Bellows (1) moulded by means of an injection moulding process with a first height (H1), to a second height (H2), which is less than the first height (H1) and heat-treated, preferably annealed, became wherein the first height (H1) corresponds to an inflated bellows (1) and the second height (H2) to an unloaded bellows (2), characterized in that the inside (11a, 12a) and / or the outside (11b, 12b) of the bellows (1) has at least one elevation (14) and / or at least one depression (15) at least in sections.

9. Bellows (1) according to claim 8, characterized in that the bellows (1) has been moulded from a thermoplastic material, preferably a thermoplastic polyurethane.

10. bellows (1) according to any one of claims 8 to 9, characterized in that the inside (11a, 12a) and / or the outside (11b, 12b) of the bellows (1) has at least one elevation (14) in sections, preferably a plurality of protrusions (14), which is formed as a rib (14), preferably as a radial rib (14).

11. bellows (1) according to any one of claims 8 to 10, characterised in that the inside (11a, 12a) and / or the outside (11b, 12b) of the bellows (1) has at least one elevation (14) in sections, preferably a plurality of protrusions (14), which is formed as a hemisphere (14).

12. bellows (1) according to any one of claims 8 to 11, characterised in that which is arranged at least one elevation (14) and / or at least one depression (15) at the annular discs (11) of the bellows (1) and / or at the end surface (12) of the bellows (1).