Mounting device for a spirit level body

Description

[0001] The invention relates to a device for fastening the vial body of a spirit level, wherein the spirit level comprises a hollow profile with at least one measuring surface to be applied to the surface to be measured and at least one outer surface, the fastening device comprising a vial holder which receives the vial body and which can be snapped into the hollow profile of the spirit level, in particular into a recess of the hollow profile provided on the outer surface, or can be fastened therein in some other way.

[0002] The invention also relates to a spirit level with such a fastening device and to a method for producing such a spirit level.

[0003] A method for manufacturing a spirit level is known from DE 196 50 683 A1. In this method, the vial body, integrated into a vial frame acting as a holder, is first inserted into the hollow body or hollow profile of the spirit level. The vial body is adjusted in the vial frame and then fixed by laser beam welding. In order to weld the vial body directly to the vial frame, the material properties of the vial body, which is made of a translucent and non-reflective plastic, in particular polymethyl methacrylate (PMMA), can be exploited. Starting from a light source, the laser beam is directed towards the vial body. The laser beam continues in the vial body until it strikes the adjacent surface of the vial frame, thus welding the vial body directly to the vial frame.The vial frame is made of an opaque and / or light-absorbing plastic, particularly acrylic butadiene styrene (ABS), in which the energy of the laser beam is converted into heat. A welding zone is created in the area of ​​the incident laser beam, within which the plastic of the vial frame is melted or plasticized. After the plastic has cooled and hardened, a solid bond with the adjacent vial body is created. The disadvantage of laser beam welding is that the translucent plastic of the vial body itself cannot be plasticized by the light energy introduced by the laser beam.

[0004] In addition to laser beam welding, other welding processes are also known for joining plastic parts. One of these is ultrasonic welding, in which the energy input and thus the welded joint are created by high-frequency mechanical vibrations that cause friction between the opposing surfaces or contact or welding surfaces of the plastic parts to be welded, and consequently heat up the material. In ultrasonic welding, an alternating current is generated with the help of a generator, which is converted into mechanical ultrasonic vibrations by a converter. The generated vibrations are transmitted to the sonotrode, and via its working surface, they are transferred under pressure to the plastic parts to be joined.During ultrasonic welding of plastics, the vibrations are introduced vertically to the welding surfaces of the plastic parts, so the working surface of the sonotrode is aligned parallel to it, and the pressure force acts vertically. Compared to laser welding, ultrasonic welding has the advantage that the welding surfaces of both plastic parts to be welded are heated, plasticized, and melted, creating a permanent, integral bond.

[0005] A spirit level whose vial body is also ultrasonically welded directly to the vial frame, here referred to as the vial holder, is known from DE 36 06 774 A1. To weld the vial body to the vial holder, the vial holder is first snapped into the metallic hollow profile of the spirit level using spring-loaded expanding cams. The vial body is then inserted into the vial holder, which is designed as a hollow body, and adjusted therein. The vial body has a flat contact surface on each of its two ends, which, in the installed position, i.e. when the vial body and vial holder are positioned as intended in the hollow profile of the spirit level, rest against respective, complementary opposite contact surfaces of the vial holder.In order to introduce the vibrations generated for ultrasonic welding vertically to the contact surfaces, the sonotrode is guided through the hollow profile of the spirit level, in which the vial holder including the vial body sits in the installed position, so that the working surface of the sonotrode is aligned parallel to the contact surfaces and the mechanical vibrations can be transmitted to the contact surfaces by means of a vertically acting compressive force. To prevent the vial body from being deflected from its already adjusted position and to reduce stresses in the material, it is necessary to weld the respective contact surfaces on both ends of the vial body together at the same time. This requires the simultaneous use of two sonotrodes with their own generators, which significantly increases the energy consumption and consequently the costs of the process. Another disadvantage is that the longer the spirit level orwhose hollow profile is, the length of the sonotrode must also be chosen to be longer so that the working surface guided through the hollow profile acts as directly as possible on the contact surfaces to be welded.

[0006] Patent DE 35 46 816 C2 discloses a method for welding the vial body of a spirit level to a vial holder, which eliminates the need to insert the sonotrodes into the hollow profile of the spirit level. This is achieved by providing the vial holder with tongues on two opposite sides of the vial body that extend through the viewing opening of the hollow profile and are located at the welding points. A disadvantage of this design is that the vial holder and the vial body protrude from the front of the spirit level even after it has been fixed or mounted, making the vial vulnerable to damage. Furthermore, the described method is only suitable for mounting head or vertical vials.

[0007] It is the object of the present invention to eliminate the disadvantages of the prior art and in particular to provide a device for fastening the spirit level body in the hollow profile of a spirit level, which enables a time- and energy-efficient and thus cost-effective production of a spirit level.

[0008] The object is achieved by a device for fastening the spirit level body of a spirit level according to claim 1, by a spirit level according to claim 8 and by a method for producing a spirit level according to claim 9.

[0009] A fastening device according to the invention of the type described in more detail above is characterized by fastening wedges designed as separate components, which are arranged in an installed position between the vial body and the vial holder in such a way that the vial body can be ultrasonically welded to the fastening wedges and / or the fastening wedges can be ultrasonically welded to the vial holder.

[0010] According to the invention, therefore, unlike what is known from the prior art, the vial body is not welded directly to the vial holder, but indirectly via fastening wedges arranged therebetween. The fastening wedges are designed as separate components and can be welded to the vial holder. The respective welded connections can then be created between the fastening wedges and the vial body and / or the fastening wedges and the vial holder using ultrasonic welding. For this purpose, the fastening wedges are preferably arranged longitudinally or end-wise between the vial body and the vial holder in the installed position.

[0011] By using mounting wedges as additional welding partners, it is no longer necessary to bring the sonotrode's working surface through the hollow profile of the spirit level to the surfaces to be welded. Instead, the sonotrode can act from the outside on the mounting wedges, which in particular form part of the outer surface of the spirit level, or the working surface is brought into contact with the mounting wedges, in particular the outer surface of the spirit level. This has the advantage that the length of the sonotrode is independent of the length of the hollow profile of the spirit level, and secondly, two welds can be joined simultaneously without the need for a second generator.

[0012] Advantageous embodiments are claimed in the subclaims and are explained in more detail below.

[0013] Thus, according to an advantageous embodiment of the invention, the vial body and the vial holder have respective contact surfaces that oppose one another in the installed position. The fastening wedges are arranged between the opposing contact surfaces in the installed position. Advantageously, the contact surfaces of the vial body are located on its end faces and lie opposite complementary contact surfaces of the vial holder. The fastening device preferably comprises exactly two fastening wedges, with one fastening wedge being positioned on each end face of the vial body, between its contact surface and the opposing contact surfaces of the vial holder, in the installed position.

[0014] In a further development of this invention, the fastening wedges have welding surfaces corresponding to the opposing contact surfaces, which, in the installed position, rest against the respective contact surfaces and can thus be ultrasonically welded to them. It may be advantageous for a fastening wedge to be provided with a welding surface on each side, so that in the installed position, i.e., when the fastening wedge is arranged between the vial body and the vial holder, one of the welding surfaces rests against a contact surface of the vial body and the other welding surface rests against a contact surface of the vial holder.

[0015] In order to define precise welding points or seams on the surfaces to be welded together, the fastening wedges can, in a particularly advantageous development, be provided with direction indicators defining respective welding zones between the vial body and the fastening wedges and / or between the vial holder and the fastening wedges. Direction indicators, also referred to as energy direction indicators, are generally known from the prior art in connection with ultrasonic welding. As a rule, direction indicators are designed as raised material noses formed along the welding surfaces of a first component, which determine the location of the energy input and thus form a defined contact or welding zone with the flat contact surface of a second component. According to the described development of the invention, for example,Two direction indicators, each shaped like a triangular prism, are molded lengthwise along a welding surface of a mounting wedge. In the installed position, the direction indicators then define precise welding zones between the vial body and the mounting wedges and / or between the mounting wedges and the vial holder.

[0016] Furthermore, an advantageous embodiment of the invention provides that the fastening device has at least one cover surface which is aligned vertically to contact surfaces of the vial body and the vial holder which are opposite one another in the installed position and / or vertically to the welding surfaces of the fastening wedges and is flat for contact with the working surface of a sonotrode of an ultrasonic welding device.

[0017] According to this embodiment, the working surface of the sonotrode can be positioned parallel to the flat top surface of the fastening device to enable optimal energy transfer into the fastening wedges and toward their welding surfaces. In this configuration, the compressive force exerted by the sonotrode acts from the outer surface of the hollow profile of the spirit level, parallel to the respective contact surfaces of the vial body or vial holder, and the welding surfaces of the fastening wedges.

[0018] Particularly advantageously, the cover surface is integrally formed onto the fastening wedges or each fastening wedge has a cover surface that runs vertically to its welding surfaces and is connected in one piece.

[0019] To ensure that the compressive force acting vertically from the working surface of a sonotrode onto the cover surface is optimally transmitted to the welding surfaces of the fastening wedges or redirected in their direction, according to an exemplary embodiment of the invention, the fastening wedges are wedge-shaped, with the material thickness of the welding surfaces decreasing from the outer surface of the hollow profile of the spirit level and / or the cover surface of the fastening device towards the interior of the spirit level. The wedge-shaped design makes it easier to insert the fastening wedges into their intended position between the opposing contact surfaces of the vial body and the vial holder. At the same time, a compressive force is exerted on the contact surfaces via the fastening wedges, thereby (pre-)fixing the vial body in the vial holder and the vial holder in the hollow profile of the spirit level.

[0020] Alternatively or optionally, it is also conceivable to form direction indicators running along the welding surfaces of the fastening wedges with a material thickness decreasing from the cover surface and in this way to realize a wedge-shaped design of the fastening wedges.

[0021] Finally, according to one variant of the invention, it is also conceivable that the contact surfaces of the vial holder are formed on spring-mounted wing elements, which wing elements can be snapped into the hollow profile of the spirit level in the installed position by means of the fastening wedges. The fixation can be achieved in particular by a wedge-shaped design of the fastening wedges and a corresponding compressive force acting on the wing elements. By joining the fastening wedges, for example wedge-shaped, between the contact surfaces of the wing elements of the vial body and the contact surfaces of the vial holder using ultrasonic welding, a compressive force is exerted on the adjacent contact surfaces due to the wedge shape, whereby the wing elements snapped into the hollow profile of the spirit level can be additionally fixed or "wedged". By connecting the vial body and holder via, for example,Two mounting wedges are ultrasonically welded to form a compact unit consisting of four components, fixed in the adjusted position: the vial body, vial holder, and two mounting wedges. At the same time, the mounting wedges act as a securement for the wing elements snapped into the hollow profile by forming a welded connection between each wing element and the corresponding mounting wedge.

[0022] The inventive problem posed at the outset is therefore also solved by a spirit level with a hollow profile, a vial body, and a fastening device with a vial holder and fastening wedges according to one of the previously described embodiments. According to the invention, in such a spirit level, the vial holder is snapped into the hollow profile or otherwise fastened therein, in particular glued or screwed. The fastening wedges are arranged between the vial body and the vial holder, with the vial body being ultrasonically welded to the fastening wedges and / or the fastening wedges being ultrasonically welded to the vial holder.

[0023] Finally, a method for producing a spirit level comprising a hollow profile with at least one measuring surface to be applied to the surface to be measured and at least one outer surface, a vial body and a vial holder, also represents a possible solution to the initially stated inventive problem. In the manufacturing method, in a preferably first method step, the vial holder is snapped into the hollow profile of the spirit level, in particular into a recess provided on an outer surface of the hollow profile, or is otherwise fastened therein, e.g. screwed or glued. In a preferably second method step, the vial body is inserted into the vial holder and adjusted therein.Fastening wedges designed as separate components are placed between the vial body and the vial holder, preferably in a third process step, and then, preferably in a fourth process step, the vial body is ultrasonically welded to the fastening wedges and / or the fastening wedges to the vial holder.

[0024] According to an exemplary variant of this manufacturing process, respective opposing contact surfaces of the vial body and / or the vial holder are ultrasonically welded to complementarily aligned welding surfaces of the mounting wedges placed between them. For this purpose, the working surface of a sonotrode of an ultrasonic welding device lies parallel to an outer surface of the hollow profile and / or parallel to a cover surface of the mounting wedges, which outer surface and / or cover surface in turn runs vertically to the opposing contact surfaces and the welding surfaces. In contrast to the methods known from the prior art for ultrasonic welding of plastics, the vibrations from the sonotrode are therefore not introduced vertically to the surfaces to be welded together (contact surfaces of the vial body or the vial holder with the welding surfaces of the mounting wedges), but rather parallel to their alignment.This significantly increases the accessibility of the sonotrode, as it is no longer necessary to pass it through the hollow profile of the spirit level, thus simplifying the manufacturing process.

[0025] Further details, features, feature (sub)combinations, advantages and effects based on the invention will become apparent from the following description of preferred embodiments of the invention and the drawings. These show in Fig. 1 a perspective view of a spirit level, in whose hollow profile a first exemplary embodiment of a fastening device according to the invention is snapped in, Fig. 2 the spirit level with the first exemplary embodiment of the fastening device according to the invention from Figure 1in a perspective exploded view, Fig. 3 a perspective view of a second exemplary embodiment of the fastening device according to the invention, Fig. 4 a perspective front view of the second exemplary embodiment of the fastening device according to the invention according to Figure 3 with an inserted spirit level body.

[0026] The figures are merely exemplary and serve only to clarify the invention. The same elements are designated by the same reference numerals.

[0027] The Figure 1a perspective view of a spirit level 200 with a hollow profile 220 made of a light metal, in particular aluminum, can be seen. The hollow profile 220 has a substantially rectangular cross-section and forms the shape of an elongated cuboid. The two end faces of the hollow profile 220 are cut off in the illustration and are therefore not visible. At least one of the remaining outer surfaces 222 is designed as a measuring surface 221 and is intended to bear against the surface to be measured with the spirit level. Starting from the outer surface 222 opposite the measuring surface 221, a circular arc-shaped recess 223 is cut out of the hollow profile 220 of the spirit level 200, which serves to accommodate the fastening device 100 including the vial body 210. In the illustration shown here, the vial holder 110 of the fastening device 100 is shown in an installed position snapped into the recess 223.The spirit level body 210 of the spirit level 200 is also shown in the installed position, ie inside the hollow body 113 (see . Figure 2 ) vial holder 110. The fastening device 100 also includes two fastening wedges 120, which are designed as separate components and, like the vial holder 110, are made of injection-molded plastic. Preferably, the vial holder 110 and the fastening wedges 120 are each made of a plasticizable plastic, for example, acrylic butadiene styrene (ABS). In the installed position, the fastening wedges 120 are each positioned on the end face between the vial body 210 and the vial holder 110.

[0028] The Figure 2 shows the spirit level 200 with the first exemplary embodiment of the fastening device 100 according to the invention from Figure 1in a perspective exploded view. Clearly visible here is the essentially circular-arc-shaped recess 223 in the hollow profile 220, into which the vial holder 110 can be snapped. For this purpose, the vial holder 110 has two wing elements 112 arranged on the end faces and designed as integral components with its hollow body 113. The wing elements 112 are spring-mounted so that they are deflected during the insertion of the vial holder 110 into the hollow profile 220 and then return to their original position. The inward-facing sides of the wing elements 112 of the vial holder 110, which is otherwise designed as a hollow body 113, each have a flat contact surface 111, which, in the installed position, lies opposite a respective outer, flat contact surface 211 of the vial body 210.

[0029] InIn the installed position, a fastening wedge 120 is also arranged on the front or longitudinal side between the vial body 210 and the vial holder 110, so that a complementarily formed welding surface 121 of the fastening wedges 120 rests in contact with each of the contact surfaces 211, 111 of the vial body 210 and the vial holder 110. InIn the first exemplary embodiment shown here, in which the contact surfaces 111 of the vial holder 110 are formed on the wing elements 112 integrally formed on the end face of the hollow body 113, the fastening wedges 120 are provided with a corresponding gap-like recess for receiving the end faces of the hollow body 113. Two direction indicators 122, also referred to as energy direction indicators, are integrally formed on the fastening wedges 120, running along the welding surfaces 121. Aligned vertically to the welding surfaces 121 and the contact surfaces 211, 111, the fastening wedges 120 each have a flat cover surface 123, which, in the installed position, is flush with the outer surface 222 of the spirit level 200.

[0030] A perspective view of a second exemplary embodiment of the fastening device 100 according to the invention is shown in Figure 3The fastening device 100 shown here basically corresponds to the first exemplary embodiment. In contrast, the vial holder 110 comprises two separate, identical component halves, which together form the cuboid hollow body 113 for receiving a likewise cuboid vial body of a spirit level (not shown here). Furthermore, the vial holder 110 is provided without the wing elements 112 (see Figure 2 ), which is why the contact surfaces 111 of the vial body 110 are also formed on the inner end faces of the hollow body 113. The vial holder 110 can be screwed, glued, or attached in any other manner known from the prior art into the hollow profile of a spirit level (not shown here). InIn an exemplary variant, the vial holder 110 is inserted obliquely into the recess of the hollow profile of the spirit level, so that its longitudinal ends are positioned ("clamped") below the hollow profile and thus held within the recess. To facilitate insertion, the longitudinal ends can be formed with a quarter-circle-shaped rounding, for example.

[0031] For attaching the spirit level body 210 (see Figure 4), its contact surfaces 211 and the contact surfaces 111 of the vial holder 110 are each ultrasonically welded to the welding surfaces 121 of the fastening wedges 120, which are arranged complementarily opposite one another in the installed position. The energy input required for this is introduced via the working surface of a sonotrode of an ultrasonic welding device, which is applied parallel to the cover surfaces 123 of the fastening wedges 120, which are aligned vertically to the welding surfaces 121. The compressive force P exerted by the sonotrode on the cover surfaces 123 is deflected (obliquely) in the direction of the respective contact surfaces 211, 111 by means of the fastening wedges 120, in particular by means of the direction indicators 122. For this purpose, the direction indicators 122 are designed with a material thickness that decreases starting from the cover surface 123.Also clearly visible in the perspective shown here is that the direction indicators 122 are integrally formed onto the fastening wedges 120 and each have a triangular cross-section or are designed in the shape of a triangular prism. The apex of the triangle determines the specific location of the energy input required for material plasticization and serves to define a linear welding zone or a weld seam. Within these welding zones, the adjacent contact or welding surfaces 211, 111, 121 are plasticized and joined in a material-to-material bond. By defining specific welding zones, stresses occurring in the material during ultrasonic welding can be reduced.

[0032] Finally, in the Figure 4 a perspective front view of the second exemplary embodiment of the fastening device 100 according to the invention according to Figure 3with an inserted spirit level body 210. In the illustration, one of the two component halves of the spirit level holder 110 of the fastening device 100 is hidden. It can be seen that a seat 114 is provided inside the spirit level holder 110, which allows the spirit level body 210 to be adjusted by means of an adjustment device (not shown) through a cradle-like movement with respect to the measuring surface 221 of the spirit level 200 (see Figure 1). The vial body 210 is held in the adjusted position by the adjustment device, while the fastening wedges 120 are inserted into their predetermined position between the vial body 210 and the opposite end-face contact surfaces 111 of the vial holder 110. Due to the wedge-shaped design of the fastening wedges 120, in particular the direction indicators 122, whose material thickness decreases from the cover surfaces 123 towards the measuring surface 221 of the spirit level 200, the vial body 210 is pre-fixed in the desired position before the welding surfaces 121 of the fastening wedges 120 are subsequently ultrasonically welded to the respective contact surfaces 211, 111 of the vial body 210 or the vial holder 110. List of reference symbols

[0033] 100Fastening device / Fastening device 110Bubble holder 111Contact surface of the bubble holder 112Wing elements 113Hollow body 114Seat 120Fastening wedge 121Welding surface 122Direction indicator 123Cover surface 200 spirit level 210Bubble body 211Contact surface of the bubble body 220Hollow profile 221Measuring surface 222Outer surface 223Recess PPressure force

Claims

1. Device (100) for fastening the level element (210) of a spirit level (200), wherein the spirit level (200) comprises a hollow profile (220) with at least one measuring surface (221) to be put on the surface to be measured and at least one outer surface (222), the fastening device (100) having a level holder (110) accommodating the level element (210), which holder can be snapped in place in the hollow profile (220) of the spirit level (200) or fastened therein in another way, characterised in that the fastening device (100) comprises fastening wedges (120) designed as separate components, which wedges, in a mounting position, are arranged between the level element (210) and the level holder (110) such that the level element (210) can be ultrasonically welded to the level holder (110), indirectly or obliquely, via the fastening wedges (120), wherein the level element (210) can be ultrasonically welded to the fastening wedges (120) and / or the fastening wedges (120) can be ultrasonically welded to the level holder (110).

2. Fastening device (100) according to claim 1, characterised in that the level element (210) and the level holder (110) have respective bearing surfaces (211, 111) opposite one another in the mounting position and, in the mounting position, the fastening wedges (120) are arranged between the opposing bearing surfaces (211, 111).

3. Fastening device (100) according to claim 2, characterised in that the fastening wedges (120) have weld contact areas (121) corresponding to the opposing bearing surfaces (211, 111), which weld contact areas abut against the respective bearing surfaces (211, 111) in the mounting position, and can be ultrasonically welded thereto.

4. Fastening device (100) according to one of claims 2 or 3, characterised in that the fastening wedges (120) are provided with energy directors (122) defining respective weld zones between the level element (210) and the fastening wedges (120) and / or between the level holder (110) and the fastening wedges (120).

5. Fastening device (100) according to one of the preceding claims, characterised in that the fastening wedge (120) has at least one cover surface (123) which is aligned vertically to the bearing surfaces (211, 111) of the level element (210) and of the level holder (110) opposite one another in the mounting position and / or vertically to the weld contact areas (121) of the fastening wedges (120), and is designed to abut in planar manner against the working surface of a sonotrode of an ultrasonic welding device.

6. Fastening device (100) according to one of the preceding claims, characterised in that the fastening wedges (120) are designed wedge-shaped, in particular with the material thickness of the weld contact areas (121) decreasing from the outer surface (222) of the hollow profile (220) of the spirit level (200) and / or of the cover surface (123) of the fastening device (100) in the direction of the inside of the spirit level (200).

7. Fastening device (100) according to one of the preceding claims, characterised in that the bearing surfaces (111) of the level holder (110) are formed at wing elements (112) housed in spring-loaded manner, which wing elements (112) can be fixed, snapped into the hollow profile (220) of the spirit level (200), in the mounting position by means of the fastening wedges (120).

8. Spirit level (200) with a hollow profile (220), a level element (210) and a fastening device (100) with a level holder (110) and fastening wedges (120) according to one of the preceding claims, characterised in that the level holder (110) is snapped into the hollow profile (220) of the spirit level (200) or fastened therein in another way, and the fastening wedges (120) are arranged between the level element (210) and the level holder (110), wherein the level element (210) is ultrasonically welded to the fastening wedges (120) and / or the fastening wedges (120) are ultrasonically welded to the level holder (110).

9. Method for producing a spirit level (200), which has a hollow profile (220) with at least one measuring surface (221) to be put on the surface to be measured, and at least one outer surface (222), a level element (210) and a level holder (110), wherein - the level holder (110) is snapped into the hollow profile (220) of the spirit level (200) or fastened therein in another way, and - the level element (210) is inserted into the level holder (110), characterised in that - fastening wedges (120) designed as separate components are placed between the level element (210) and the level holder (110), and - subsequently, the level element (210) is ultrasonically welded to the fastening wedges (120) and / or the fastening wedges (120) are ultrasonically welded to the level holder (110).

10. Production method according to claim 9 characterised in that respective opposing bearing surfaces (211, 111) of the level element (210) and / or of the level holder (110) are ultrasonically welded to weld contact areas (121) of the fastening wedges (120) placed lying therebetween, aligned in complementary manner thereto, wherein the working surface of a sonotrode of an ultrasonic device abuts parallel to an outer surface (222) of the hollow profile (220) and / or parallel to a cover surface (123) of the fastening wedges (120), which outer surface (222) and / or cover surface (123) run(s) vertically to the opposing bearing surfaces (211, 111) and the weld contact areas (121).