TECHNICAL FIELD

The present invention relates to a welding fixture for fixing a hollow element e.g. a sealing frame during the installation of such in an opening of e.g. a wall or floor.

BACKGROUND

Today different welding fixtures are known and commonly used on

manufacturing sites in order to perform a precise welding process. But what happens when the welding site is not the same as the manufacturing site and instead is a place with limited space, e.g. in a submarine or any other construction site? Welding is often used when e.g. a sealing frame is to be installed in an opening of a wall or a floor. These types of installations are often seen at various construction sites or in other places where electrical wires, pipes or any other objects are to be installed through walls or floors.

Requirements on the installation process and its tolerances when installing e.g. a sealing frame for electrical wires, gets tougher and tougher to achieve due to more strict rules regarding safety and environment.

A type of wedge is often used today when performing welding operations on a sealing frame that is to be installed into an opening of a wall. The wedge is knocked in by a hammer or the like, between the frame and the wall in order to fix the position of the frame. However, during the welding process heat is transferred to the material of the frame causing the frame to deform and often expand in an undesired way. If the inner and outer dimensions of the frame change the sealing both between the frame and the wall and within the frame may be affected and after installation not achieve the requirements set up for the specific purpose. If using a wedge there are also difficulties in removing the wedge after the welding operation and often the installer need to use a hammer or a cutting tool to remove it which could damage the frame, the wall , the weld or the wedge which then could not be used again. Also, the installation of the wedge could cause damages to the frame and the wall and cause disturbance when creating the weld between the frame and the opening.

Other techniques used today meet with difficulties when it comes to preserving the dimensions of the frame and the opening of the wall before, during and after a welding operation which can lead to a deterioration of the important seal both between the installed object and the wall and within the hollow object once all elements are in place in the opening. SUMMARY

An object of the present invention is to provide improvements over prior art. This object is achieved by a technique defined in the appended independent claims; certain embodiments being set forth in the related dependent claims.

In an aspect of the present invention, there is provided a welding fixture for size fixing a hollow element, e.g. a sealing frame, comprising a first fixture member having a first and a second engagement surface and a second fixture member having a first and a second engagement surface. The welding fixture further comprises a compression unit arranged to fixate the first fixture member aligned with and spaced apart from the second fixture member, such that the engagement surfaces of the first fixture member and the engagement members of the second fixture member are facing each other and are configured to exert a clamping effect on said hollow element. Each fixture element comprises a first and a second counter surface defining the maximum expansion of said hollow element during use. The present invention provides a welding fixture which is very advantageous to use before, during and after a welding process when e.g. a sealing frame is to be installed in an opening of a wall or a floor by means of welding. The welding fixture has an easy construction which makes it easy to bring to the installation site and easy to work with for installers with different welding experiences. In fact that the welding fixture only consists of a few components makes it easy to manufacture and assembly.

In an embodiment of the invention each fixture member has an elongated shape extending along a longitudinal axis and comprises a first end portion, a second end portion and an intermediate portion arranged between the first and second end portions. The first end portion comprises a first counter surface and the second end portion comprises a second counter surface, wherein the first and second counter surface are arranged to extend in a direction perpendicular to the longitudinal axis. The features of the welding fixture are designed to withstand the rigors of the welding process so that it can perform its task during a long period of time.

In an alternative embodiment the first end portion further comprises a third counter surface and the second end portion further comprises a fourth counter surface, wherein the area of the third and fourth counter surfaces differs from the area of the first and second counter surfaces. This is advantageous since the welding fixture may be adjusted to perform under different circumstances, e.g. at different depths of frames which are to be installed. In yet another embodiment each fixture member is arranged so that the first and the second counter surfaces are configured to be the counter surfaces in use or wherein one or both fixture members are turned 180° around their longitudinal axis and arranged so that the third and fourth counter surfaces are configured to be the counter surfaces in use. This means that it is very easy to switch between the different alternative appearances of the welding fixture.

In an embodiment each fixture member further comprises a first recess provided in the area where the intermediate portion passes to the first end portion, and a second recess provided in the area where the intermediate portion passes to the second end portion. The recesses are provided instead of otherwise frail corners and are particularly advantageous since they prevent cracks from easily forming in the fixture member due to the tensions and high temperatures used in the installation and welding process. The recesses prolong the length of life of the fixture member considerably. Also, the recesses prevent unnecessary wear on the corners and edges of the frame placed in between the counter surfaces.

In one further embodiment each fixture member comprises fixture arms placed perpendicular to each other, giving a cross form in plan view

In one embodiment the fixture arms are lockable in different position in respect of a center part in the form of a house.

In an alternative embodiment the shape of the first and second fixture member are identical which is beneficial in a manufacturing process.

In another aspect of the present invention there is provided a method of installing a welding fixture which has been described above, comprising the steps:

- providing the first fixture member, having engagement surfaces on one side of the hollow element, e.g. a sealing frame

- providing the second fixture member, having engagement surfaces aligned with the first fixture member and spaced apart, such that the engagement surfaces of the first fixture member face the engagement surfaces of the second fixture member, on the opposite side of said hollow element; and

- tightening the compression unit such that the first and second engagement surfaces of the first fixture member together with the first and second engagement surfaces of the second fixture member are exerting a clamping effect on the hollow element.

In an alternative embodiment the first and/or the second fixture member is tuned 180° around its longitudinal axis before tightening the compression unit. All advantages with the method of the present invention will be clear when reading the following description and studying the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described in the following, reference being made to the appended drawings which illustrate non-limiting examples of how the inventive concept can be reduced into practice.

Fig. 1 shows two welding fixtures according to a first embodiment of the present invention arranged in a sealing frame;

Fig. 2 shows one of the welding fixtures of Fig. 1 ;

Fig. 3 shows the welding fixture of Fig. 2 with an alternative orientation of fixture members of the welding fixture;

Fig. 4 is a front view of the welding fixture in Fig. 2;

Fig. 5 is a top view of the welding fixture in Fig. 2;

Fig. 6 is a bottom view of the welding fixture in Fig. 2;

Fig. 7 is a side view of the welding fixture in Fig. 2;

Fig. 8 shows a welding fixture according to a second embodiment of the present invention arranged in a sealing frame;

Fig. 9 is a perspective view of the welding fixture of Fig. 8;

Fig. 10 shows a welding fixture according to a third embodiment of the present invention arranged in a sealing frame; and

Fig. 11 is a perspective view of the welding fixture of Fig. 10.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to Fig. 1 two welding fixtures 10, arranged in and partly around a hollow element, which in this case is a sealing frame F, are illustrated. The welding fixture 10 is supposed to be used before, during and after a welding process for installing the frame F in an opening of e.g. a wall V or floor in order to retain the size properties of the frame F during the welding process. The welding process involves high temperatures affecting the material of the frame F which can lead to unwanted deformations and size adjustments of the frame F which may be prevented by the welding fixture 10 seen in Figs 1-7. The installation process will be described in more detail later. However, during the installation process often only one welding fixture 10 is used, but if necessary, or if a framework comprising several frames is to be installed, several welding fixtures 10 may be used. Each welding fixture 10 comprises a first fixture member 20a, a second fixture member 20b and a compression unit 40. The first fixture member 20a and the second fixture member 20b are basically identical, apart from one feature, a through hole which in one fixture member 20a is unthreaded and in the other fixture member 20b is threaded. The fixture members 20a, 20b are also referred to as fixture elements. The welding fixture 10 and its components can be seen from different angles and views in Figs 2-7.

Each fixture member 20a, 20b has an elongated shape extending along a longitudinal axis A of the fixture member 20a, 20b which preferably is manufactured, e.g. extruded, casted or cut, as one single piece. The elongated shape has an

intermediate portion 21 with a thickness, seen e.g. from a front view in Fig. 4, which varies along the longitudinal axis A, where a center part 22 of the intermediate portion 21 is the thickest and where the thickness decreases in both directions of the longitudinal axis A from the center part 22. On each side of the center part 22 there is an adjacent part 23a, 23b which, again seen from a front view in Fig 4, has a substantially rectangular shape where the two longer sides of the rectangle extends along the longitudinal axis A. The adjacent part 23a, 23b may serve as an engagement part for the frame F with two possible engagement surfaces 24a, 24b, 24c, 24d, on each side if the center part 22. The engagement surfaces 24a, 24b, 24c, 24d on each side of the center part 22 are arranged opposite each other, i.e. on opposite sides of the rectangular shaped adjacent part 23a, 23b. In another embodiment the adjacent parts 23a, 23b may have another shape, such as square or round.

At each end of the elongated shaped fixture members 20a, 20b, next to the adjacent parts 23a, 23b, there are two identical end portions 26a, 26b arranged. The end portions 26a, 26b have an almost rectangular shape but where its shorter sides 27a, 27b this time are parallel to the longitudinal axis A and its longer sides 28a, 28b are perpendicular to the longitudinal axis A. The end portion 26a, 26b is arranged not centered with respect to the longitudinal axis A but offset from it, which means that the longer sides 28a, 28b of the end portion 26a, 26b extends more in one direction B, away from the longitudinal axis A, than it does in the opposite direction B' . The advantage of this feature can be seen in Fig. 2 and 3 where the same welding fixture 10 is shown in two different appearances. Fig. 2 shows a first example where the extension 29 of the longer side 28a of the end portion 26a, 26b of the first fixture member 20a is greater in the direction B towards the opposite second fixture member 20b and vice versa. Fig. 3 shows a second example, where each fixture member 20a, 20b has been turned 180° around its longitudinal axis A, i.e. where the extension 29 of the longer sides 28a of the first fixture member 20a is greater in the direction B' away from the opposite second fixture member 20b or vice versa.

In a further example, not shown in any figure, the two fixture members may be arranged so that the first fixture member has its longer extension in the direction towards the second fixture member and that the second fixture member has its shorter extension in the direction towards the first fixture member. Depending on the frame type and it size and shape it is desired to be able to choose the extension 29a, 29b of the longer sides 28a, 28b in order to perform the installation of the frame F in the opening of a wall V and the welding process as good as possible.

The inner longer sides 28b of the end portions 26a, 26b, i.e. the side facing the intermediate portion 21 and the opposite end portion, comprises four possible counter surfaces 3 la, 3 lb, 3 lc, 3 Id, two which are larger 3 la, 3 lb than the others 3 lc, 3 Id due to the offset position of the end portion 26a, 26b. This can easier be seen in Fig. 4. In Fig. 2 the two counter surfaces 3 la, 3 lb with the larger area are the active counter surfaces and in Fig. 3 the two counter surfaces 3 lc, 3 Id with the smaller area are active counter surfaces. Each fixture member 20a, 20b may be arranged so that the counter surfaces 3 la, 3 lb with the larger area are configured to be the counter surfaces in use or wherein one or both fixture members 20a, 20b are turned 180° around their longitudinal axis A and arranged so that the counter surfaces 3 lc, 3 Id with smaller area are configured to be the counter surfaces in use.

Each counter surface 3 la, 3 lb, 3 lc, 3 Id is arranged to prevent movements and particularly expansions of the frame F before, during and after a welding process. Due to the high temperatures that are necessary in the welding process most materials would change its properties, and most of them would expand. If the frame F would expand during the welding process or for any reason before or after the welding process, the counter surfaces 3 la, 3 lb, 3 lc, 3 Id form a stop. It is very important to be able to maintain the size properties of the frame F during the installation process in the wall V since pre-determined objects are suppose to fit in the frame F and at the same time create a tight sealing during use, and the tolerances are small. The inner length L of each fixture member 20a, 20b is therefore very important and well thought-out in order to manage the small tolerances that are required. Said inner length L is the distance between the counter surfaces 3 la, 3 lb, 3 lc, 3 Id to be placed at opposite sides of the frame F. The fixture member 20a, 20b may thus be manufactured in every desired length L and width W depending on which type of object that is to be installed. In the area where the adjacent part 23a, 23b meets or pass into the end portion 26a, 26b a recess 32a, 32b, 32c, 32d in the shape of a three-quarter circle is provided, see e.g. Fig. 3. Each recess 32a, 32b, 32c, 32d extends in a transverse direction C with respect to the extension of the longitudinal axis A, along the entire width W of the fixture member 20a, 20b. The recesses 32a, 32b, 32c, 32d are provided instead of otherwise frail corners and are particularly advantageous since it prevents cracks from easily forming in the fixture members 20a, 20b due to the tensions and high

temperatures used in the installation and welding process. The recesses 32a, 32b, 32c, 32d prolongs the length of life of the fixture members 20a, 20b considerably. Also the recesses 32a, 32b, 32c, 32d prevent unnecessary wear on the corners and edges of the frame F placed in between the counter surfaces 3 la, 3 lb, 3 lc, 3 Id. In an alternative embodiment the recesses may have another shape.

In order to connect the two fixture members 20a, 20b a compression unit 40 is used, see e.g. Fig. 3. The compression unit 40 preferably includes a screw 41, at least one washer 42 and a compression spring 43. The screw 41 extends through a center hole 44a of the first fixture member 20a, which in the figures can be seen as the upper fixture member and down to a center hole 44b of the second fixture member 20b, which in the figures can be seen as the lower fixture member. Preferably the center hole 44a of the upper first fixture member 20a is an unthreaded hole and the center hole 44b of the lower second fixture member 20b is a threaded hole in order to be able to adjust the distance D between the two fixture members 20a, 20b. An installer/user may thus easily adjust the distance D between the upper first fixture member 20a and the lower second fixture member 20b in order to fix the position of the frame F there in between. The threaded center hole 44b of the second fixture member 20b is preferably a through hole but may in alternative embodiments not be a through hole, i.e. have a bottom, which prevents the screw from extending all the way through the second fixture member 20b.

The compression spring 43 is arranged around the screw 41 along the part of the screw 41 extending between the first fixture member 20a and the second fixture member 20b. Preferably the compression spring 43 is provided as a protection of the screw 41 against e.g. waste material from the welding process that otherwise would get stuck on the screw which could lead to making the screw unusable. The compression spring 43 prolongs the life of the screw 41 and therefore also the life of the entire welding fixture 10.

The welding fixture 50 of Figs. 8 and 9 comprises a first fixture member 51a, a second fixture member 5 lb and a compression unit. The first fixture member 51 has a first fixture arm 52a, a second fixture arm 52b, a third fixture arm 52c and a fourth fixture arm 52d, wherein all fixture arms 52a-52d extends from a center part. The fixture arms 52a-52d are placed forming a cross as seen in plan view. The first and second fixture arms 52a, 52b are placed on opposite sides of the centre part and the third and fourth fixture arms 52c, 52d are placed on opposite sides of the centre part. The first and second fixture arms 52a, 52b may or may not be of another length than the third and fourth fixture arms 52c, 52d. In the same way as for the first fixture member 51a, the second fixture member 51b comprises a first fixture arm 53a, a second fixture arm 53b, a third fixture arm 53c and a fourth fixture arm 53d. The fixture arms 53a-53d of the second fixture member 5 lb correspond with the fixture arms 52a-52d of the first fixture member 51a and are positioned in a similar way.

The first and second fixture arms 52a, 52b, of each fixture member 51a, 51b are placed in line with each other and form a fixture element together with the center part. In a corresponding way the third and fourth fixture arms 52c, 52d, of each fixture member 51, 51b are placed in line with each other and form a fixture element together with the center part. Thus, the fixture members 51a, 51b as shown in Figs. 8 and 9 can be said to be formed of two fixture elements placed perpendicularly to each other.

Except for the number of fixture arms the welding fixture 50 of Figs. 8 and 9 corresponds with the previously described welding fixture. Thus, each of the fixture arms 52a-53d of the fixture members have engagement surfaces, end portions, counter surfaces of different area and recesses corresponding with the previously described fixture members 20a, 20b. For description of the parts for engagement with the frame F reference is made to the description above, where said parts are described in connection with the previously described welding fixture 10. In the same way as described previously the welding fixture 50 has a compression unit comprising a screw 41 and a spring 43. The first fixture member 51a and/or the second fixture member 51b may be turned 180°, depending on the desired area of the counter surface of respective fixture member 51a, 51b.

The welding fixture 60 of Figs. 10 and 11 comprises a first fixture member 61a, a second fixture member 61b and a compression unit. The first fixture member 61a comprises a first fixture arm 62a, a second fixture arm 62b, a third fixture arm 62c and a fourth fixture arm 62d. The second fixture member 61b comprises a first fixture arm 63a, a second fixture arm 63b, a third fixture arm 63c and a fourth fixture arm 63d. The fixture arms 62a-62d of the first fixture member 61a are received in a house 64a, forming a center part of the first fixture member 61a. In a corresponding way the second fixture member 61b also comprises a house 64b, forming a center part. The fixture arms 62a-63d of the first and second fixture member 61a, 61b, respectively, are placed in a cross form, as seen in plan view. Each fixture arm 62a-63d of the first and second fixture members 61a, 61b has a bent end 65 at an outer free end, which bent end 65 is to be placed on the outside of the frame F. Each fixture arm is received in a through opening of respective house 64a, 64 and is moveable in a longitudinal direction for each fixture arm in relation to the house 64a, 64b. Each fixture arm has one or more notches 67 for locking respective fixture arm in a desired position. In the shown embodiment said locking is accomplished in that an end of a screw 68, shown as an Allen screw in Figs. 10 and 11, goes down into a notch 68 of respective fixture arm. The notches 68 of the fixture arms are placed corresponding to standardized sizes of the frame F. The compression unit of the welding fixture 60 of the shown embodiment corresponds with the compression units of the previously described embodiments. The shown

compression unit of the welding fixture 60 comprises a screw 66. In the shown embodiment there is no spring surrounding the screw 66, but a person skilled in the art realizes that a spring may be arranged in the same way as for the previously described embodiments.

The first and second fixture arm 62a, 62b, 63a, 63b of each fixture member 61a, 61b are placed projecting in opposite directions from the house 64a, 64b. The first and second fixture arms 62a, 62b, 63a, 63b form a fixture element together with the house 64a, 64b of each fixture member 61a, 61b. In a corresponding way the third and fourth fixture arms 62c, 62d, 63c, 63d of each fixture member 61a, 61b are placed projecting in opposite directions from the house 64a, 64b. The third and fourth fixture arms 62c, 62d, 63c, 63d form a fixture element together with the house 64a, 64b of each fixture member 61a, 61b. Thus, the fixture members 61a, 61b as shown in Figs. 10 and 11 can be said to be formed of two fixture elements placed perpendicularly to each other.

For the welding fixture 60 of Figs. 10 and 11 each fixture arm 62a-63d has an engagement surface, which is the surface of respective fixture arm 62a-63d to be facing the frame F. The inner side of the bent end 65 of respective fixture arm 62a-63d forms a counter surface. Said counter surface of respective fixture arm 62a-63d has the same function as the counter surfaces of the previously described welding fixtures 10, 50.

The welding fixture 60 as shown in Figs. 10 and 11 may also be used with only two fixture arms for each fixture member 61a, 61b. If only two fixture arms are used it is normally the third and fourth fixture arms 62c, 62d, 63 c, 63 d of respective fixture member 61a, 61b that are used, i.e. at the shortest extension of the frame F. However, in some instances fixture members 61a, 61b having only two fixture arms are placed at the longest extension of the frame F, in which case it is the first and second fixture arms 62a, 62b, 63a, 63b of respective fixture member 61, 61b that are used. If welding fixtures 60 having only two fixture arms 62c, 62d, 63c, 63d for each fixture member 61a, 61b are used two or more such welding fixtures 60 may be placed on a frame F, in a way corresponding to the welding fixtures of Fig. 1.

The installation process of the frame F may preferably begin with the step of placing the frame F in the opening of a wall V, and then arranging a welding fixture 10, 50, 60 in the frame F but may also begin by arranging the welding fixture 10, 50, 60 in the frame F and then placing the frame F in the opening of a wall V. Either way, the welding fixture 10, 50, 60 is installed in the frame F by providing the two fixture members 20a, 20b and the compression unit 40 connecting the fixture members 20a, 20b together. The members 20a, 20b are provided one on each side of the opening of the frame F in such a way that the edges of the frame F are in contact with the engagement surfaces 24a, 24b, 24c, 24d of the fixture members 20a, 20b. By tightening the screw 41 the welding fixture 10, 50, 60 fixes the position of the frame F in between the fixture members 20a, 20b.

The welding process preferably comprises the following steps:

arranging the frame F in the opening of e.g. a wall V

mounting the welding fixture 10, 50, 60 within and partly around the frame F. The welding fixture 10, 50, 60 will then remain in its position within and around the frame F during the entire welding process until the welding fixture 10, 50, 60 and the frame F has cooled down. As described above the welding fixture prevent the frame F from changing its dimensions due to the added heating during the welding process. Due to the specific application and the dimensions of the frame F and/or the opening the fixture members 20a, 20b may be turned 180° around it own longitudinal axis A in order to provide different areas of counter surfaces 3 la, 3 lb, 3 lc, 3 Id. This means that the desired features of the welding fixture 10, 50, 60 may be achieved by turning the fixture members 20a, 20b before every usage.

for embodiments having moveable fixture arms, said fixture arms are locked in appropriate positions - welding the frame F to the opening of the wall V, preferably by first perform a tacking process around the frame, then perform a fillet welding process and finally perform a seal weld on the backside of the frame F.

The welding fixture 10, 50, 60 is designed to be a flexible and mobile tool which any welder easily can bring on to the welding site and use. Its simple shape and small size makes it easy to understand how it should be installed before an installation process of e.g. a frame begins and no necessary training of how to use the welding fixture should be needed. Due to it design and it specific features the welding fixture 10, 50, 60 is able to perform its task with high precision even though the tolerances are small.

Although the welding fixture 10, 50, 60 is never directly exposed to the heat of the welding the fixture 10, 50, 60 is preferably made of steel that resists heat well.

Finally, although the inventive concept has been described above with reference to specific embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the invention is limited only by the accompanying claims and, other embodiments than the specific above are equally possible within the scope of these appended claims.