Clamp with tensioning screw and torque limiter

Description

[0001] The invention relates to a clamp, in particular a hose clamp, with a clamping device comprising a clamping screw, according to the preamble of claim 1.

[0002] Hose clamps, also known as hose clamps or tension clamps, such as worm-drive clamps, typically consist of a ring-shaped metal band and are used to secure a hose end to a fixed connection or hose connector. Hose clamps are primarily used in plumbing, automotive manufacturing, and mechanical engineering. They are generally manufactured according to DIN 3016 / 3017 and other industry standards and are made of metal.

[0003] To tighten the clamp, it has a tensioning device with an adjusting screw. This screw is positioned so that tightening it reduces the inner diameter of the hose clamp. This presses the hose, which is gripped by the clamp, onto the fitting, creating a radial seal.

[0004] In radial sealing, the hose material or the material of the clamping device is strongly deformed by the clamping force, which is why overtightening the clamping screw or applying too much preload can damage the hose and / or the clamping device.

[0005] Attachable, adapter-like devices for ensuring a predetermined torque when tightening a hose clamp's clamping screw are already known in the prior art. Document DE 42 11 132 C2, for example, describes such a torque-locking device for use with hose clamps with clamping screws in motor vehicles. KR 10 2011 0057873 A also describes a clamp with such a clamping device. Furthermore, DE 42 31 003 A1, for example, describes a so-called shear bolt for a clamp with an inner head section that is accessible to a slotted screwdriver after the outer head section has broken off.

[0006] A disadvantage here is that, in addition to the clamping screw, an additional device or torque cap must be used to ensure a predefined torque, which is also relatively complex to manufacture.

[0007] The aim of the invention is to overcome these and other disadvantages of the prior art and to create a clamp with a clamping device that is cost-effectively constructed with simple means and few components and enables a simplified assurance of a predetermined torque.

[0008] The main features of the invention are specified in the characterizing part of claim 1. Embodiments are the subject of claims 2 to 10.

[0009] In a clamp with a clamp band having two ends that can be connected to each other by a clamping device, the clamping screw having a head section and a shaft section, wherein the shaft section has a threaded area with which the clamping screw can be screwed onto the clamping device, wherein the head section has a clamping head for applying a preload force in a preload direction, wherein the head section has a mounting head for tightening the clamping screw and for ensuring a predefined torque, wherein the clamping head has a shear plane on its upper side, wherein the shear plane is arranged between the clamping head and the mounting head, wherein the mounting head shears off from the clamping head of the clamping screw at the shear plane when a predefined torque is applied or exceeded, it is provided according to the invention that the clamping head has at least two edges.

[0010] Overall, the controlled shearing prevents overstressing of the clamp and the clamping device or the clamped components.

[0011] The term "clamp" generally refers to all types of clamps that have at least one clamping device. The invention relates in particular to the aforementioned hose and tension clamps, worm gear clamps, profile clamps, exhaust clamps and ball zone exhaust clamps, pipe clamps, and mounting clamps with brackets.

[0012] By incorporating a shear plane, which acts as a predetermined breaking point and is positioned between the clamping and mounting heads, the mounting head can be sheared off precisely when a selected torque is reached. Advantageously, the mounting head also serves to tighten the clamping screw. The integral design of the mounting and clamping heads eliminates the need for an additional torque-locking cap. When the predefined torque is applied or exceeded, the shear forces at the shear plane between the mounting and clamping heads are so great that the mounting head shears off the clamping screw at the shear plane. Therefore, the use of a calibrated and regularly tested electric or pneumatic screwdriver is no longer necessary.

[0013] When the mounting head shears off, sharp edges can form at the shear or fracture point. Therefore, the fracture point is susceptible to corrosion. Due to the flat shear plane on the top of the clamping head, deburring of sharp edges after shearing is advantageously facilitated. In another design variant, the shear plane can be coated to achieve corrosion protection (long-range protection effect).

[0014] In an advantageous embodiment, the invention provides that the clamping screw is formed integrally with the clamping head and the mounting head. This allows all sections of the clamping screw to be manufactured from screw blanks with minimal manufacturing effort, for example by turning, pressing, chipless forming, rolling or milling.

[0015] In a preferred embodiment, the mounting head has a conical projection on its underside, with the conical projection being formed between the shear plane and the mounting head. The conical projection facilitates shearing of the mounting head when the predefined torque is exceeded and can, for example, be designed as an acute-angled annular groove. Preferably, the smaller diameter of the conical projection faces the shear plane. When the predetermined torque is applied or exceeded, the mounting head preferably shears completely off at the shear plane. The conical shape of the projection and the targeted positioning of the smaller diameter at the shear plane effectively reduce the shear area. This also promotes clean shearing and reduces sharp edges.

[0016] In another embodiment, the mounting head has a recess on its upper surface for the positive-locking insertion of a tool when tightening the clamping screw, the recess being, for example, cross-shaped. No special tool is then required to tighten the clamping screw. Due to the cross-shaped recess, conventional screwdrivers can be used. Preferably, the mounting head has at least two external edges, in particular parallel to each other, and is preferably designed as a hexagon. This allows the use of Phillips and slotted screwdrivers, as well as wrenches, to apply torque or to tighten the screw. Alternatively, designs that allow the use of an internal Torx, external Torx, or internal hexagon are also conceivable.

[0017] In another important embodiment, the invention provides that the clamping head has a lower contact surface which, when the clamping screw is tightened, establishes a press contact with the clamping device of the clamp, the press contact being established via a circumferential preload lip on the contact surface. Preferably, the clamping head has a disc-shaped base body that extends between the circumferential preload lip and the shear plane and is larger in diameter than the mounting head. The clamping head is particularly preferably hexagonal in design. Due to its multi-sided design, the clamping screw can be manually loosened via the clamping head, even after the mounting head has sheared off. The disc-shaped base body of the clamping head is larger than the mounting head and presses against the component to be fastened or against the clamping device when the screw is tightened.The circumferential preload lip improves the force transmission advantageously in the preload direction.

[0018] It is particularly preferred that the circumferential preload lip of the clamping head projects further in the preload direction than the base body of the clamping head. Due to the projecting, lip-shaped design of the preload lip, the preload force is introduced at the circumferential preload lip in the form of line pressure. This reduces the contact area, and the lower contact surface reacts more rigidly under a load opposite to the preload direction. Overall, due to the reduced circumferential contact via the preload lip, an increased surface pressure is achieved between the clamping head and the clamping device.

[0019] In a further embodiment, the shaft has a conical transition to the base body of the clamping head. This advantageously creates a locking mechanism against unwanted loosening, because the conical shape of the transition increases the frictional and transverse forces acting in the screw shaft when the clamping screw is tightened and, as the screw shaft expands, effectively provides a better metallic seal.

[0020] In a further embodiment, the invention provides that the mounting head is designed as a hollow profile directly at the shear plane of the clamping head. Preferably, the mounting head is also polygonal in this embodiment to allow for subsequent manual loosening. The recess on the top of the mounting head is cylindrical. Due to the mounting head's direct, thin-walled design at the shear plane, the overall manufacturing effort of the clamping screw is reduced. This also saves on material costs because the conical section is eliminated and less raw material is required. These two factors together reduce overall production costs. To further reduce the shear area at the shear plane, the mounting head can preferably be conical.

[0021] In another embodiment, the clamp is a hose clamp for securing a hose end to a fixed connection or hose connector. Especially with hose clamps, which are particularly common in motor vehicles, the use of a tensioning screw according to the invention is particularly advantageous for ensuring a predetermined torque. When tightening hose clamps, there is an increased risk of damaging the hose material by applying excessive torque. This can, in turn, lead to leaks. Furthermore, the tensioning screw according to the invention significantly simplifies tightening the hose clamp without the need for additional components.

[0022] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. The drawings show: Fig. 1a a schematic view of a clamping screw according to the invention; Fig. 1b a schematic side view of a clamping screw according to the invention; Fig. 1c a schematic view of a clamping screw according to the invention without a mounting head; Fig. 1a a detailed view of the head and shaft section of the clamping screw; Fig. 2a a sectional view of an alternative embodiment of the clamping screw; Fig. 2b a detailed view of a head region of the clamping screw made of Fig. 2a Fig. 2 shows a schematic view of the clamping screw. Fig. 2a Fig. 3a a clamping screw according to the invention with a worm gear clamp; Fig. 3b a clamping screw according to the invention with a profile clamp; Fig. 3c a clamping screw according to the invention with an exhaust clamp; Fig. 3a a clamping screw according to the invention with a pipe clamp;

[0023] The in Fig. 1a to Fig. 1dThe clamping screw generally designated by 1 is suitable for being screwed onto the clamping device of a clamp with a clamp band that has two adjacent ends which can be connected to each other by a clamping device, in order to reduce the inner diameter of the clamp and to tighten the clamp (not shown).

[0024] How to find out, especially in Fig. 1d As can be seen, the clamping screw 1 has a head section K and a shaft section S. A mounting head 20 is provided in the area of ​​the head section K for tightening the clamping screw 1 and ensuring a predefined torque M. In addition, the head section K has a clamping head 10 for applying a preload force when tightening the clamping screw 1.

[0025] Furthermore, the shaft section S has a screw shaft 6 and an adjoining threaded area 30, with which the clamping screw 1 can be screwed onto the clamping device (not shown). Furthermore, the following are described in the embodiments according to Fig. 1 and Fig. 2 The clamping screws shown are formed in one piece.

[0026] The clamping head 10 is provided on its upper side with a shear plane 3, which is arranged between the clamping head 10 and the mounting head 20. The mounting head 20 is designed such that, when the predefined torque M is applied or exceeded, it shears off the clamping head 10 of the clamping screw 1 at the shear plane 3 (see in particular [reference]). Fig. 1c ).

[0027] As in the Fig. 1b and 1dAs shown, the mounting head 20 has a conical projection 5 on its underside, the conical projection 5 being formed between the shear plane 3 and the mounting head 20. The conical projection 5 tapers in the preload direction. Thus, the larger diameter of the conical projection 5 faces the mounting head, whereas the smaller diameter of the conical projection 5 faces the shear plane 3 on the top side of the clamping head 10.

[0028] Furthermore, the mounting head is provided on its upper side with a cross-shaped recess 22 for the positive locking insertion of a tool (e.g., screwdriver) when tightening the clamping screw 1 and is designed as an (external) hexagon. One of the six edges is designated with the reference numeral 24.

[0029] The clamping head 10 has a lower contact side 12 which, when the clamping screw 1 is tightened, establishes a press contact on the clamping device of the clamp, the press contact being initiated via a circumferential preload lip 11 on the contact side 12.

[0030] By combining the Fig. 1d , Fig. 2a and Fig. 2b It becomes apparent that the clamping head 10 has a disc-shaped base body that extends between the circumferential preload lip 11 and the shear plane 3 and is larger in diameter than the mounting head 20. The circumferential preload lip 11 of the clamping head 10 projects further in the preload direction X than the disc-shaped base body of the clamping head 10. The shank 6 has a conical transition 7 to the disc-shaped base body of the clamping head 10. Furthermore, the clamping head 10 has at least two edges 2 for manual release.

[0031] Figs. 2a to 2cThese provisions refer to an alternative embodiment of the invention, in which the mounting head 20 is designed as a hollow profile directly adjacent to the shear plane 3 of the clamping head 10. The shear plane 3 can be understood as a separating plane at which the mounting head 20 separates from the clamping head 10 during shearing. The recess 22 is cylindrical on the upper surface of the mounting head 20, and the outer geometry of the mounting head has several edges 24.

[0032] The Figs. 3a to 3d various application examples of the clamping screw 1 according to the invention are illustrated. In these examples, different clamps 100 are clamped or fixed using the clamping screw 1 according to the invention.

[0033] In Fig. 3a The clamping screw 1 is attached to a clamping device of a worm gear clamp 100.

[0034] Fig. 3b Figure 1 shows a profile clamp 100 which is tensioned at its ends via a clamping screw 1.

[0035] In Fig. 3c An exhaust clamp or spherical zone exhaust clamp 100 is shown. The clamping screw 1 according to the invention is passed through openings at the ends of the exhaust clamp 100.

[0036] Fig. 3d Figure 1 shows a pipe clamp 100 having two overlapping legs which are tightened by a clamping screw 1. The clamping screw 1 passes through the legs.

[0037] The clamp with clamping screw according to the invention can generally refer to pipe and clamping clamps where ensuring a predefined torque is required. In particular, the invention relates to applications in the field of automotive engineering, such as hose clamps with clamping heads that are connected via the clamping screw. The clamp can also be designed as a worm-drive clamp with a housing in which the clamping screw is guided. Alternatively, the clamp can also be designed as a profile clamp, mounting clamp, pipe clamp, or clamping clamp for connecting two pipe ends. Reference symbol list

[0038] K Head section screw 10 chuck S Shaft section screw 11 Preload lip X Pre-tension direction 12 Contact page M Predefined torque 20 Mounting head 22 Exclusion 1 Tensioning screw 24 edge 2 edge 30 Thread area 3 Shear plane 100 clamp 5 Conical approach 6 shaft 7 Conical transition

Claims

1. Clip (100) having a clip band which has two ends which are connected to each other by a clamping apparatus which has a clamping screw (1) having a head portion (K) and a shaft portion (S), wherein the shaft portion (S) has a thread region (30) and the head portion (K) has a clamping head (10) for applying a pretensioning force and an assembly head (20) for tightening the clamping screw (1), wherein the clamping head (10) has a shear plane (3) at the upper side thereof, wherein the shear plane (3) is arranged between the clamping head (10) and the assembly head (20), wherein the assembly head (20) shears off from the clamping head (10) of the clamping screw (1) at the shear plane (3) if a predefined torque (M) is applied, characterized in that the clamping head (10) has at least two sides (2).

2. Clip according to Claim 1, characterized in that the clamping screw (1) is configured integrally with the clamping head (10) and the assembly head (20).

3. Clip according to Claim 1 or 2, characterized in that the assembly head (20) has at the lower side thereof a conical attachment (5), wherein the conical attachment (5) is formed between the shear plane (3) and the assembly head (20).

4. Clip according to one of the preceding claims, characterized in that the assembly head (20) has at the upper side thereof a recess (22) for the positive-locking insertion of a tool when the clamping screw (1) is tightened, wherein the recess (22) is in particular cross-like.

5. Clip according to one of the preceding claims, characterized in that the assembly head (20) has at least two sides (24), wherein the assembly head (20) is particularly in the form of a hexagon.

6. Clip according to one of the preceding claims, characterized in that the clamping head (10) has a lower contact side (12) which produces a pressing contact at the clamping apparatus of the clip when the clamping screw (1) is tightened, wherein the pressing contact is produced over a circumferential pretensioning lip (11) at the contact side (12).

7. Clip according to Claim 6, characterized in that the clamping head (10) has a plate-like main body which extends between the circumferential pretensioning lip (11) and the shear plane (3) and which is configured to be greater in diameter than the assembly head (20).

8. Clip according to Claim 7, characterized in that the circumferential pretensioning lip (11) of the clamping head (10) projects further in the pretensioning direction (X) than the main body of the clamping head (10).

9. Clip according to Claim 7 or 8, characterized in that the shaft (6) has a conical transition (7) to the main body of the clamping head (10).

10. Clip according to one of the preceding claims, characterized in that the clip is a hose clip for securing a hose end to a fixed connection or to a hose connector.