METHOD FOR PRODUCING AN UPHOLSTERY SPRING, UPHOLSTERY SPRING, MATTRESS, AND UPHOLSTERED FURNITURE

Abstract

A method for producing an upholstery spring, such as for upholstered furniture or mattresses includes several steps. One of the steps includes at least regionally applying a heat-sensitive colour indicator to a spring steel wire before, during or after the bending of the spring steel wire. The spring steel wire is heated to at least the changeover temperature of the colour indicator. The upholstery spring is then finished.

Claims

1. A method for producing an upholstery spring for upholstered furniture or mattresses, comprising the following steps: at least regionally applying a heat-sensitive colour indicator to a spring steel wire before, during or after a bending of the spring steel wire; heating the spring steel wire to at least a changeover temperature of the colour indicator; and finishing the upholstery spring.

2. The method according to claim 1, wherein the spring steel wire is heated to above 250 C. for heat treatment and activation of the colour indicator.

3. The method according to claim 1, wherein the spring steel wire is heated to a temperature between 280 C. and 320 C. for heat treatment and activation of the colour indicator.

4. The method according to claim 1, wherein the colour indicator is applied to the spring steel wire by an immersion bath.

5. The method according to claim 1, wherein the colour indicator is applied with a thickness between 0.05 m to 1.5 m.

6. The method according to claim 1, wherein a copper-containing coating is applied as the colour indicator.

7. The method according to claim 1, wherein the colour indicator is applied only in some regions to the spring steel wire.

8. The method according to claim 7, wherein the colour indicator is applied to a central region of the upholstery spring, which central region deforms upon loading.

9. An upholstery spring, produced by a method for producing the upholstery spring for upholstered furniture or mattresses, the method comprising the steps of: at least regionally applying a heat-sensitive colour indicator to a spring steel wire before, during or after a the-bending of the spring steel wire; heating the spring steel wire to at least a the-changeover temperature of the colour indicator; and finishing the upholstery spring.

10. A mattress with an upholstery spring, where the upholstery spring is produced by the method of claim 9.

11. A unit or piece of upholstered furniture formed with an upholstery spring produced by the method of claim 9.

12. The mattress produced according to the method of claim 10, further comprising a step of providing a viewing window on a cover for the upholstery spring or a unit comprising a plurality of upholstery springs.

13. The unit or piece of upholstered furniture produced according to the method of claim 11, further comprising a step of providing a viewing window on a cover for the upholstery spring or a unit comprising a plurality of upholstery springs.

Description

[0010] The invention is explained in more detail below with reference to an exemplary embodiment shown in the attached drawings, wherein:

[0011] FIG. 1 shows a photographic view of an upholstery spring with a coating of a colour indicator according to the invention before and after the heat treatment, and

[0012] FIG. 2 shows a conventional upholstery spring without a colour indicator.

[0013] FIG. 2 shows an upholstery spring without a coating of a heat-sensitive colour indicator.

[0014] It can be seen that the spring steel wire from which the upholstery spring is made has the same colour everywhere and it is not optically apparent whether a heat treatment has been carried out with this upholstery spring in order to make the spring steel wire tougher.

[0015] On the left side in FIG. 1, an upholstery spring according to the present invention is shown. The upholstery spring is helically wound in a middle region between two end rings arranged in parallel and is coated in this central region with a heat-sensitive colour indicator. As can be seen from the view, the central region has a different colour from the two uncoated end rings of the upholstery spring. The middle region is clearly darker, which is caused by the colour change of the heat-sensitive colour indicator as a result of the heat treatment. On the right side, an upholstery spring with colour indicator and without heat treatment is illustrated. It can be seen clearly that the colour is uniform. As a heat-sensitive colour indicator, a copper-containing coating was applied to the wire electrochemically in a thickness of between 0.15 m to 0.75 m. For this purpose, the wire was passed through an immersion bath and a voltage was applied to the spring steel wire, so that the copper-containing material was deposited on the surface. By means of this method, the layer thickness and the coated regions can be adjusted comparatively exactly.

[0016] In this case, the colour indicator can be applied to the still undeformed spring steel wire, so that the latter can be deformed into the shape of an upholstery spring only after coating. Preferably, a complete coating is then applied. However, it is also possible first to form the spring steel wire into an upholstery spring and at least partially coat the already formed spring steel wire.

[0017] After applying the colour indicator, the bent spring steel wire was subjected to a heat treatment, wherein the bent spring steel wire is heated to a temperature between 210 C. to 250 C. By heating to this temperature, the colour indicator was activated so that an optically recognizable colour change was made in the middle region.

[0018] In the exemplary embodiment shown, only the middle region of an upholstery spring is coated with a colour indicator, wherein it is also possible to apply the colour indicator completely to the upholstery spring. Through the coating of the colour indicator in sections, it is easier to visually recognize the colour change by the heat treatment. In addition, it is possible to provide the coating only in the area of the upholstery spring, which deforms upon loading, i.e. in particular the region between the two end rings.

[0019] The upholstery spring can be bent to form different spring types. Thus, the upholstery spring can be used as a Bonell spring, a pocket spring, an open coil or as a different type of spring. The upholstery springs can also be combined into a plurality of upholstery springs and then processed into mattresses or upholstered furniture.

[0020] In order to enable the end customer to check whether high-quality upholstery springs have been used in the mattress or the upholstered furniture, at least one transparent viewing window or one formed by a recess can be provided in the cover so that an optical check is possible as to whether the upholstery spring is heat-treated.