WO2001002137A1

WO2001002137A1 - Device for making it easier to loosen screwed connections

Info

Publication number: WO2001002137A1
Application number: PCT/EP2000/005830
Authority: WO
Inventors: Stefan Fenchel
Original assignee: Stefan Fenchel
Priority date: 1999-07-06
Filing date: 2000-06-23
Publication date: 2001-01-11
Also published as: EP1200229A1; WO2001002137B1; DE19930919A1; DE19930919C2

Abstract

The invention relates to a device which makes it easier to loosen a screwed connection. The inventive device comprises an intermediate ring (12) having at least one surface (22) which is located on the first side (18) thereof and is slightly inclined with respect to a plane (E) which is perpendicular to the longitudinal direction (L) of the screwed connection. Said device also comprises a counterpart (14) which has similarly inclined surfaces (33) on the side facing the intermediate ring (12), whereby said inclined surfaces have the same angle of inclination (α) as the surfaces (22) of the intermediate ring (12) . The inclined surfaces (22 and 33) come to rest upon each other when the screwed connection is tightened, whereby the inclination (α) of the inclined surfaces (22 and 33) is located in an opposite direction to the thread pitch of the screwed connection. In order to provide an improved device, enabling a screw connection which has become tightened through use to be loosened in a simple manner requiring only a limited amount of force and dispensing with blows to the thread, whereby the inventive device can be used in a reliable manner for high power machines such as core drills, the inclination of the surfaces (22) of the intermediate rings (12) and the inclination of the surfaces (33) of the counterpart (12) are directed towards the periphery and the intermediate ring (12) is provided with a good grip surface (28) on the second side (26) thereof.

Description

Device for easier loosening of a screw connection

The invention relates to a device for easier loosening of a screw connection.

For screw connections that tighten when used in the direction of rotation, as is the case for example with the connection between an angle grinder and the associated grinding wheel or with a threaded connection of a drill bit tube to a core drilling motor, there is the general problem of this screw connection, for replacing the drill bit or the grinding wheel to loosen again. As a rule, this requires a large force, which often, especially with core drilling machines, can hardly be applied by hand. Heavy hammers are then often used and struck on the threaded connection. This is not only very complex, but can also damage or even destroy the threaded connection.

From angle grinders it is known to actuate a locking button after the motor has been switched off and while the grinding wheel is still rotating, so that a short and correspondingly strong impulse is exerted on the screw connection. This process requires complex technology, which is correspondingly inexpensive. From DE 36 13 987 a device for easier loosening a screw fastening a grinding wheel of an angle grinder is known. This has an inner flange with two or three trapezoidal projections, which are received in recesses of a counterpart. The base of the recesses is beveled in accordance with the trapezoidal shape of the projections. When tightening the screw fastening, the end faces of the projections should come into contact with the base area. The inclination of the base surface is opposite to the thread pitch. When loosening the screw connection, only a slight relative movement between the inner flange and the counterpart is necessary to take the greatest pressure off the tightened thread and to ensure easy loosening of the screw connection, because the relative movement can cause the inner flange and the counterpart to move axially To move towards each other slightly.

This device is intended for angle grinders so that the grinding wheel can be changed without tools. Angle grinders work with a relatively small power of up to about 2kW, and the torques that occur are correspondingly small, namely up to about 200 numbers.

However, this known device cannot be used, for example, for core drilling machines which work with powers of up to 40 kW and with torques of approximately 1000 Nm. The high forces that occur with such machines would easily destroy the projections. This applies in particular if the projections, as described in DE 36 13 987, have a relatively small contact surface. There, only the oblique end face of two or three projections comes into contact with the corresponding base area of the recesses. The force on these surfaces will be correspondingly large.

Furthermore, the projections have a trapezoidal shape, which means that the inclined end faces are flat surfaces. The base areas of the Accordingly, recesses are also formed as flat surfaces. In the event of a rotary movement which occurs when the screw fastening is tightened, the flat surfaces can only come into contact with a very specific, exact angular position of the inner flange with respect to the counterpart. If there are slight deviations from this angular position, the contact between the end face of a projection and the base of a corresponding recess will only be along a line. A flat design of the inclined surfaces is no problem for smaller machines, such as angle grinders, since the screw connection is tightened by hand and the inclined surfaces slide into a suitable position. When operating the angle grinder, only lower torques occur, so that the appropriate angular position of the inner flange and counterpart to one another is not changed. Such protrusions are not practicable for machines with high outputs that apply correspondingly high torques and would be destroyed in use.

With core drilling machines, the screw connections via which the drill bit tubes are screwed onto the machine shaft cannot be loosened after use, even with ordinary tools. Large levers and sledgehammers are then used, with the result that the machine, the drill bit tube or the screw connection are frequently damaged.

Furthermore, special connections are known for core drilling machines, into which special core drills, which no longer have a screw connection, can be inserted by simply plugging them in. These drill chucks contain a complex technology and are therefore very expensive to manufacture. In a disadvantageous manner, the chuck and the core drill have to be adapted to one another.

It is also known to provide copper washers for such tightening screw connections. These copper washers are flexible to a certain extent, so that after use, the tension on the Thread is not so high and, if necessary, easier loosening is possible. The copper disc is destroyed when it is used. Furthermore, easier loosening is only possible if the copper disc has not yet been fully compressed, which is usually not the case after a long period of use. As a rule, there is a very high tension on the tightened thread even when using copper washers, so that the screw connection can only be loosened with very great forces.

Starting from this prior art, it is an object of the invention to avoid the aforementioned disadvantages and to provide a device with which a screw connection which has tightened in use can be released again in the simplest possible manner, and without the use of excessive forces, So in particular without striking the thread, the device should be able to be used reliably for machines with large outputs, such as core drilling machines.

This object is achieved by a device with the features of claim 1.

According to the invention, the inclination of the surfaces of the intermediate ring is now formed in the circumferential direction in a generic device for easier loosening. An inclined surface is then almost a part of a helix. The surface inclined in the circumferential direction is not a flat surface. The surfaces of the counterpart are also inclined (helical) in the circumferential direction. This ensures that the surfaces always come into contact with each other in every angular position and a linear contact, which would lead to the destruction of the intermediate ring immediately with high forces, is excluded.

In machines that work with large forces, such as core drilling machines, the intermediate piece and the counterpart will still rotate against one another during operation, which is in the configuration according to the invention has no effect, since the surfaces still remain in mutual contact, which prevents the intermediate ring or counterpart from being destroyed. It would be different with the device according to DE 36 13 987, because if the inner flange twisted relative to the counterpart during operation, only a linear contact would be provided.

In the configuration according to the invention, the high forces occurring in particular in core drilling machines can also be absorbed by the device for easier loosening without the destruction occurring. Only with the configuration according to the invention is a device created which makes it possible to use it on machines with high forces, such as core drilling machines.

The intermediate ring also has a non-slip surface on its second side. This measure is necessary because during operation of the machine, for example a core drilling machine, enormous torsional forces occur due to the pressure exerted on the intermediate ring and due to the inclined surfaces, which in themselves cause the hissing ring and the counterpart to "slide together" along the inclined surfaces. If the intermediate ring and the counterpart would slide together, however, the device according to the invention would be ineffective, since when the screw connection is loosened, the intermediate ring and the counterpart would not be able to rotate relative to one another, since they are already as close as possible to one another in the axial direction, with the result that the pressure does not drop In order to prevent this collapse, the non-slip surface is provided, which just prevents the intermediate ring from rotating against the direction of thread rotation and from sliding against the counterpart.

The non-slip surface has the further advantage that when the screw connection is loosened, the intermediate ring first reliably faces one another rotates the counterpart and can take the tension off the thread, which is by no means a given the high forces with which the screw connection was tightened in use. This measure is not trivial, because one could initially assume that since the contact surfaces on the second side of the intermediate ring are larger than on the first side, the frictional forces on the second side should also be larger, which would make an additional grip unnecessary. The formation of a non-slip surface significantly increases the reliability of the device.

This relatively simple device, which is very inexpensive, since, for example, existing screw connections can be equipped with the device according to the invention in a very simple manner by the counterpart being formed by a second intermediate ring, tightening screw connections can also be used by core drilling machines, that is to say machines that work with great power can be operated easily and without great effort. Impacts on the thread to take the pressure off it are no longer necessary.

This detaching effect can be adjusted by the angle of inclination of the inclined surfaces. For screw connections that tighten with great forces, larger pitch angles, which are defined as the angle between the surfaces and the plane perpendicular to the longitudinal direction of the screw connection, are used. Smaller pitch angles can be used for screw connections that tighten with smaller forces.

Advantageous embodiments of the invention are the subject of the dependent claims.

In order to have enough leeway when loosening the screw connection, that is, the intermediate ring opposite the counterpart, which virtually interlocks with each other are enough to be able to turn back in the release direction, it can be advantageous to arrange a thin layer of a resilient material between the intermediate ring and the counterpart, which is compressed when tightened and thereby causes the intermediate ring and counterpart to be sufficiently far apart when tightened can be rotated and the steep flanks located between adjacent teeth of the intermediate ring or counterpart can move away from each other, so that it is then possible to turn back when loosening.

The intermediate ring and the counterpart are advantageously held together by holding means. Then they are always in the correct position relative to each other, both when tightening and when loosening the screw connection. The holding means should consist of an elastic, preferably resilient material to allow sufficient rotation of the intermediate ring relative to the counterpart.

In a simple and inexpensive embodiment, the holding means is a non-curing adhesive. In a further embodiment, the holding means is formed by pins made of elastic material, the pins being connected both to the intermediate ring and to the counterpart.

The holding means is particularly advantageously formed by a retaining ring made of elastic material, which is connected both to the intermediate ring and to the counterpart and which is arranged in the region of the circumference of the intermediate ring and the counterpart, because then the gap between the intermediate ring and counterpart is through closed the retaining ring and no dirt can get into the space. The device according to the invention can then function and function properly even under conditions in which a lot of dirt accumulates, as is the case, for example, in particular with core drilling machines, for example when drilling concrete. In a simple embodiment of the invention, the non-slip surface is formed by a rough surface. For example, small elevations, such as ribs or the like, can be provided on the side of the intermediate ring.

If the materials that are screwed together are themselves very hard, e.g. in core drilling machines, the grip of the non-slip surface can be determined by an applied to the surface, e.g. glued on, powder made of a hard material, in particular diamond, silicon carbide or hard metal. When the screw connection is tightened, the diamond grains or the like are then pressed into the surfaces coming into contact, depending on the material hardness, so that when the screw connection is released, the intermediate ring always first rotates relative to the counterpart.

So that the inclined surfaces coming into contact cannot be damaged and it is ensured that the intermediate ring is rotated relative to the counterpart, the intermediate ring advantageously consists of a surface-hardened material.

In order to be able to equip existing screw connections with the device according to the invention, the counterpart is a second intermediate ring which is identical to the first. The two intermediate rings then only have to be screwed, the intermediate rings can be relatively thin and take up little space.

It can also be provided that the counterpart is a screw head, a drilling head, a grinding wheel or another part to be fixed with the screw connection. Then only the additional intermediate ring has to be inserted in order to use the device according to the invention. The intermediate ring could then be held directly on the counterpart, ie the drill head or the like. The device according to the invention can be used with particular advantage for a screw connection with which a drill bit tube can be fixed in a core drilling machine, since particularly great forces occur here and when drilling, the drill bit tube is tightened strongly and was previously only releasable with correspondingly large forces, i.e. hammer blows , With the device according to the invention, the drill bit tube can be unscrewed by hand.

The invention is explained in detail below using exemplary embodiments with reference to the drawing. The drawing shows:

1 shows a device according to the invention;

2 shows an intermediate ring of the device according to the invention from FIG. 1;

3 shows an embodiment of the device according to the invention in cross section along the line IV-IV from FIG. 1;

Fig. 4 shows another embodiment of the invention

Device in cross section along the line IV-IV of Figure 1;

5 shows a screw connection for fastening a core drilling tube to a core drilling machine with the device according to the invention.

A device 10 according to the invention has an intermediate ring 12 and a counterpart 14, which is also an intermediate ring 16 in a first exemplary embodiment (FIG. 1). The device 10 shown is designed for screw connections with a right-hand thread. The intermediate ring 12 shown individually in FIG. 2 has teeth on its first side 18, the teeth 20 of which are formed by surfaces 22 arranged in the circumferential direction, which are slightly inclined in the circumferential direction with respect to a plane E perpendicular to the longitudinal direction L of a screw connection, in such a way that the inclination of the surfaces 22 of the thread pitch is opposite. Due to the formation of the inclination in the circumferential direction, the inclined surfaces 22 are not flat surfaces but are quasi parts of a helix. This becomes particularly clear if only one surface were available, which would also be possible in principle, which would then represent a piece of a spiral that rotates through 360 ° and has a specific pitch angle α.

If the pitch angle of the thread pitch is defined negatively with respect to the plane E and = 0 ° lies in the plane E, then the angle of inclination α, that is to say the angle between the surfaces 22 and the plane E, is positive. The angle of inclination, which could also be referred to as a pitch angle, can be relatively small in magnitude, e.g. a few degrees. The smaller or larger the angle α, the smaller or larger the detaching effect of the device according to the invention. In the limit, if = 0 °, the detachment effect would also not be present and the intermediate ring would have a smooth surface on its first side like an ordinary washer. Steep flanks 24 are arranged between two adjacent teeth 20, which can preferably be rounded (not shown).

On its second side 26, the intermediate ring has a non-slip surface 28, which can be formed by ribs 30 running radially on the side 26 or other geometric elevations. In a preferred embodiment of the invention, not shown, the grip of the surface is realized by a powder, for example glued on, made of a hard material, in particular diamond, silicon carbide or hard metal. The second intermediate ring 16 provided as counterpart 14 in the first exemplary embodiment shown in FIG. 1 is identical to the intermediate ring 12 with teeth 32 with inclined surfaces 33 and non-slip surface 34. In the assembled position (FIG. 1), the second intermediate ring 16 is merely positioned rotated by 180 ° about the plane E with respect to the first intermediate ring 12. The surfaces 33 of the teeth 32 of the second intermediate ring 16 come to bear against the surfaces 22 of the teeth 20 of the first intermediate ring 12. The angles of inclination of the surfaces 33 and the surfaces 22 are identical, so that when the intermediate ring 12 and counterpart 14 lie against one another, the surfaces 22 and 33 can lie on the entire surface. If the intermediate ring and counterpart come to lie on top of one another, as shown in FIG. 1 and as is also realized by holding means described in more detail below, approximately 90% of the total area has come into contact.

In a further development of the invention, a thin layer 36 of a resilient material is arranged at least in some areas between at least some of the surfaces 22 and 33 that come into contact, the function of which is explained below.

In a preferred embodiment of the invention, the intermediate ring 12 and the counterpart 14 are held together by holding means 38. The holding means 38 is preferably formed from an elastic material, so that the intermediate ring 12 and the counterpart 14 are held in the correct position before screwing together a screw connection and can still be rotated relative to one another.

The holding means 38 can comprise one or more pins 40 made of rubber-elastic material, the ends of which are each fixed in the intermediate ring 12 and the counterpart 14 (FIG. 3). Alternatively, the holding means 38 could also be formed by a holding ring 42 which is firmly connected both to the intermediate ring 12 and to the counterpart 14. For this purpose, the intermediate ring 12 has a step 44 on the edge of its first side 18 and the counterpart 14 has one corresponding stage 46 on which the retaining ring 42 is mounted and fixed, for example glued.

The mode of operation of the device according to the invention is described below:

Fig. 5 shows an application example. A drill bit tube 56 can be screwed onto a drive shaft 50 of a motor 52 of a core drilling machine 54. The device 10 according to the invention is arranged between a stop 58 of the drive shaft 50 and the tube 56 and is first plugged onto a threaded rod 60 of the tube 56. When using the core drilling machine 54, the screw connection between the drive shaft 50 and the tube 56 will tighten. The surfaces 22 and 33 of the device 10 come into mutual contact. If tightened further, the intermediate ring 12 and the counterpart 14 cannot rotate further against one another, since the inclined surfaces 22 and 33, the inclination of which counteracts the thread pitch, would push them apart in the axial direction, which is not possible. The grippy surfaces 28 and 34 of the intermediate ring 12 or counterpart 14 press with their elevations 30 into the abutting stop 58 of the drive shaft 50 and the corresponding stop 59 of the tube 56. When using the diamond powder, the diamond granules will press into the surfaces 28 and 34 on the one hand and into the stops 58 and 59 on the other hand, regardless of the degree of hardness of the materials used.

To loosen the screw connection, the tube 56 is now rotated in the direction of the arrow relative to the drive shaft 50. Since the tube 56 with the counterpart 14 and the drive shaft 50 with the intermediate ring 12 are frictionally connected to one another via the non-slip surfaces 28 and 34, initially only the intermediate ring 12 can rotate relative to the counterpart 14. Even with minimal twisting against each other, the pressure on the thread is immediately removed, since the intermediate ring 12 and that Counterpart 14 can move axially towards each other due to the inclined surfaces 22 and 33. When the pressure is removed from the thread, the tube 56 can even be completely unscrewed by hand.

It is clear from this functional description that an essential feature of the device 10 according to the invention is the inclined surfaces 22 and 33. These do not necessarily have to be designed as flanks of teeth. In principle, other shapes are also conceivable as long as inclined surfaces are formed with a corresponding angle of inclination, which can come into mutual contact.

So that the loosening of the screw connection is possible in the manner according to the invention, the flanks 24 of the intermediate ring 12 must have a sufficient distance in the circumferential direction from the corresponding flanks of the counterpart 14 (FIG. 1), so that the counterpart 14 is loosened relative to the intermediate ring 12 can turn back at least a minimal distance. This only needs to be a few degrees or only a fraction of a degree, depending on the size of the angle of inclination α.

The layer 36 and / or the holding means 38 ensure that the intermediate ring 12 and the counterpart 14 are held in such a position relative to one another before the screw connection is tightened that when the surfaces 22 and 33 come into contact when tightening, the latter there is sufficient distance between the flanks.

It is also conceivable that the intermediate ring is made in one piece with a tool, for example a drill bit tube, and the counterpart is made in one piece with a drill connection.

Claims

Patent claims

1. Device for easier loosening of a screw connection with an intermediate ring (12) which on its first side (18) has at least one surface (22) slightly inclined with respect to a plane (E) perpendicular to the longitudinal direction (L) of the screw connection and with a counterpart (14), which on its side facing the intermediate ring (12) also has inclined surfaces (33) which are the same

Inclination angles (α), like the surfaces (22) of the intermediate ring (12) and the inclined surfaces (22 and 33), come into contact with one another when the screw connection is tightened, the inclination (α) of the inclined surfaces (22 and 33) of the thread pitch is opposite to the screw connection, characterized in that the inclination of the surfaces (22) of the intermediate ring (12) and the inclination of the surfaces (33) of the counterpart (14) is formed in the circumferential direction and that the intermediate ring (12) on its second side ( 26) has a non-slip surface (28).

2. Device according to claim 1, characterized in that between the intermediate ring (12) and the counterpart (14) at least in regions a thin layer (36) made of a flexible material is arranged.

3. Apparatus according to claim 1 or 2, characterized in that the intermediate ring (12) and the counterpart (14) are held together by holding means (38).

4. Device according to one of the preceding claims, characterized in that the holding means is a non-curing adhesive.

5. Device according to one of the preceding claims 1 to 3, characterized in that the holding means (38) is formed by pins (40) made of elastic material, which are connected both to the intermediate ring (12) and to the counterpart (14) ,

6. Device according to one of the preceding claims 1 to 3, characterized in that the holding means (38) is formed by a retaining ring (42) made of elastic material, which is connected both to the intermediate ring (12) and to the counterpart (14) and which is arranged in the region of the circumference of the intermediate ring (12) and the counterpart (14).

7. Device according to one of the preceding claims, characterized in that the non-slip surface (28) is formed by a rough surface (28).

8. Device according to one of the preceding claims, characterized in that the grip of the non-slip surface is realized by an applied to the surface, for example glued, powder made of a hard material, in particular diamond, silicon carbide or hard metal.

9. Device according to one of the preceding claims, characterized in that the intermediate ring consists of a surface-hardened material.

10. Device according to one of the preceding claims, characterized in that the counterpart (14) is a second intermediate ring (16) which is identical to the first.

11. Device according to one of the preceding claims 1 to 9, characterized in that the counterpart is a screw head, a drilling head, a grinding wheel or any other part to be determined with the screw connection.

12. Use of a device according to one of the preceding claims for a screw connection with which a drill bit tube is fixed in a core drilling machine.