WO2001066960A1

WO2001066960A1 - Device for the anchorage of a shaft

Info

Publication number: WO2001066960A1
Application number: PCT/SE2001/000333
Authority: WO
Inventors: Evert Svensson; Anders Carlsson
Original assignee: Svenska Expander Ab
Priority date: 2000-03-09
Filing date: 2001-02-16
Publication date: 2001-09-13
Also published as: AU2001236269A1; SE0000790D0; SE0000790L; SE514035C2

Abstract

Device for anchoring a cylindrical shaft end (1b) in a circular through-opening, such as in a fixing lug (2). The shaft end (1b) has at least one plane chamber (3), which forms an acute angle with the centre line of the shaft (1). The anchoring device comprises a wedge element (4) substantially filling a space between the chamfer (3) and the corresponding wall section of the through-opening, the end (4a) of which wedge element is designed to be acted upon by a head (6a) of a screw element (6) arranged on the shaft (1), in order thereby to create the anchorage by pressing in the wedge element (4). The device furthermore comprises a tightening body (7) arranged between the head (6a) and the wedge element (4) and designed, by tighetning of the screw element (6), to brace against, and be capable of turning somewhat about, a support point (9), arranged on the shaft end (1a) and situated on the opposite side of the screw element (6) to the wedge (4).

Description

DEVICE FOR THE ANCHORAGE OF A SHAFT

The present invention relates to a device for anchoring a cylindrical shaft end in a circular through-opening for the shaft end, for example in a fixing lug, as specified in the pre-characterising clause of claim 1.

A known solution according to US-A-5 538 356 shows a shaft, which is provided at its ends with a tapered section and a central threaded section. The tapered section has alternating tapered and plane surfaces. A united collar of alternating internally tapered and plane wedge elements is located around the tapered section and a movement up to the tapered section can be imparted to the said collar by means of a nut on the threaded section, thereby making it possible to fix the shaft end to a surrounding part.

Another known solution WO/9934120 has a shaft, which is locked against the fixing lugs by means of wedges. The wedges are pressed by means of a screw head in order to produce the wedging action between a chamfering of the shaft and the fixing lugs.

An object of the present invention is to produce a device by means of which an improved anchorage of a shaft is achieved.

According to the present invention a device is produced for anchoring a cylindrical shaft end in a circular through-opening for the shaft end according to claim 1.

Preferred embodiments of the device in addition have any one or more of the characteristics specified in the subordinate claims.

The device according to the invention has a number of advantages, including the following:

A torque applied to the screw elements imparts a strong force to the wedge, since none of the constituent parts is subject to plastic deformation to any great extent. The constituent parts can therefore be assembled manually using conventional tightening tools. Dismantling of the device is also simplified for the same reasons. By directing the force that presses in the wedge substantially axially at the maximum force levels a good bearing contact is obtained between the wedge and the shaft throughout the entire tightening sequence.

The part of a tightening body that constitutes a flange will function as a physical stop and prevent the shaft falling out of the fixing lugs. This also means that further locking devices on the end surfaces or the fixing lugs will be superfluous, thereby resulting in a minimal axial projection at the sides and a low manufacturing cost.

The tightening body is designed to give the device increased resistance to vibrations and to reduce the need for readjustments.

Other factors having a positive impact on the cost profile for the device according to the invention include the fact that the device has few constituent parts, and these are easy to manufacture and provide great flexibility.

The invention will be explained in more detail below with the aid of examples of embodiments of the present invention and with reference to drawings attached, in which:

Fig. 1 shows an exploded sketch drawing of a first embodiment of the device according to the invention. Figure 1 also shows an alternative screw element.

Fig. 2 shows a section through a shaft, which is provided with the device according to the invention as in Figure 1 and located in a pair of fixing lugs formed with through-openings for the shaft.

Fig. 3 shows a sketch of an alternative embodiment of the device according to the invention, in which two wedge elements have been arranged with an angle of 120° between them.

Fig. 4 shows the device according to Figure 1 in a position before tightening has been commenced.

Fig. 5 shows the device according to Figure 1 in a position as tightening is being commenced.

Fig. 6 shows the device according to Figure 1 in a tightened position. The same reference numbers for identical or analogous parts are used throughout the description of all figures.

The shaft 1 is designed to be anchored at its ends, preferably in a pair of fixing lugs 2 or the like, formed with through-openings for the shaft, see Figures 1 and 2. At each end of the shaft there is a guide chamfer la, which facilitates introduction of the shaft into the fixing lugs 2. There are two further chamfers 3, 8 at each end lb of the shaft, of which a first chamfer 3 is designed so as to produce a plane, substantially elliptical segment-shaped slide surface between a chord at the end of the shaft and the circumferential surface of the shaft. The slide surface forms an angle α, preferably in the interval 10-30°, with the longitudinal axis of the shaft. Between the first chamfers 3 at the shaft ends there is a cylindrical shaft section. When the shaft 1 is located in the fixing lugs, wedges 4 with a shape corresponding to the plane chamfered part of each shaft end and with a section, axially extended at the shaft end adjacent to the guide chamfer 1 a and terminated at a circular segmental end 4a comprising a chord, are inserted in openings in the said fixing lugs. The wedges 4a are arranged with the tip directed towards the cylindrical middle section of the shaft 1 and are preferably manufactured from a harder material than the shaft. At the shaft end (and in Figure 1 directly under each first chamfer 3) there is a tapped axial bore 5. A screw element 6 is designed to interact with the tapped bore 5, so that when the screw element is screwed in towards the end of the shaft the head 6a of the screw element presses by way of a tightening body 7 against the circular segmental end surface 4a of the wedge, thereby imparting a movement to the wedge 4 in an axial direction towards the cylindrical section. On the opposite side of the screw element 6 and at an interval from the threaded cylindrical part 6b of the screw element there is a support point, around which the tightening body 7 will turn during tightening.

At one of its ends the second chamfer 8 meets the first chamfer 3 and at its other end it meets the distal surface of the shaft 1 and forms a thrust line 9 with this connection. The thrust line 9 is designed to provide guidance for turning of the tightening body 7 and hence also for movement of the wedge 4.

In an alternative embodiment the screw element 6 extends through the entire length of the shaft 1. An example of a full-length screw 6' is shown in Figure 1. In this embodiment there is a through-opening for the screw element 6' throughout the entire shaft, which is achieved, for example, by boring out or by manufacturing the shaft from tubing. The screw element 6' is thus designed to interact with its fixing at the opposite end of the shaft. This embodiment is advantageous in cases where it is desirable to turn the screw connection from one side. The device is preferably identical at each end of the shaft and therefore only one end of the shaft will be described below. At the shaft end lb is the guide chamfer la and first chamfer 3, which foπns the plane slide surface. Figure 2 shows the fixing lug 2 with shaft end and wedge 4 inserted. The tightening body 7 extends radially outside the circumferential surface of the shaft 1 and is designed to form a stop and to prevent the shaft 1 leaving the fixing lugs 2 in an axial direction. The screw element

6 is designed to interact with the tapped bore 5, so that when the screw element 6 is screwed in towards the end of the shaft, the head 6a of the screw element presses by way of the tightening body 7 against the end 4a of the wedge and presses the wedge 4 along the plane slide surface, so that the shaft end is anchored in the fixing lug 2 by wedging action and frictional engagement.

An example of an embodiment with a large shaft diameter has a number of wedges 4 at the end of the shaft, as shown in Figure 3. The said wedges are here arranged in the same way as shown in Figure 1 and Figure 2. The figure shows how two wedges 4 have been arranged at the end of the shaft with an angle of 120° between them, so that the locking force is distributed uniformly around the circumference of the shaft end.

When the screw element 6 is screwed into the shaft end the tightening body 7 is applied to the wedge 4 on a first side of the screw element 6 (that is to say the wedge side) and after screwing in further also on the other side of the screw element 6 (that is to say on the support point side) against the shaft end and in an area on or in proximity to the thrust line 9, as shown in Figures 4 and 5. The space between the tightening body and the second chamfer 8 forms a gap and is designed to give the tightening body room to turn around the thrust line 9 during tightening.

During tightening the tightening body is turned into the correct position, for example from the position in Figure 4 to the position in Figure 5. In Figure 4 the tightening body 7 extends beyond the thrust line 9 and during the initial tightening stage therefore forms a first point of contact with the distal surface of the shaft 1 at a distance from the thrust line 9. During the final tightening stage, however, the tightening body 7 is designed to bear substantially against the thrust line 9 The force on the wedge 4 increases during tightening so that when the wedge 4 has reached its correct position the wedge 4 is pressed with maximum force and the tightening body

7 has attained a position substantially perpendicular to the axis of the screw element 6. In this position, largely the entire head 6a of the screw element rests against the tightening body 7, thereby achieving a straight axial loading in the screw element 6. The highest axial force of the device on the wedge 4 therefore coincides with an advantageous load case for the screw element 6, that is to say axial tensile loading.

The distance between the threaded cylindrical part 6b of the screw element and the thrust line 9 is preferably many times greater than the distance between the cylindrical part 6b and the wedge 4. This means, among other things, that the force from the tightening body 7 will be higher on the edge 4 than on the thrust line 9 and that a slight movement of the wedge 4 in an axial direction does not result in any greater rotation of the tightening body 7. Thus an adjustment of the position of the wedge 4 does not mean that the screw element 6 is exposed to any appreciable oblique loading.

The tightening body 7 is clamped between the thrust line 9, the wedge 4 and the head 6a and is allowed to bend down in the gap between the thrust line 9 and the wedge 4. The device is therefore designed to withstand vibrations, so that any tendency to unscrew is prevented.

It will be obvious to a person skilled in the art that the invention is not confined to the embodiments described above, but can rather lend itself to modifications within the scope of the idea of the invention defined in the following claims. For example, the device may be designed so that certain parts are integrated with one another. In an alternative embodiment, for example, the tightening body 7 and the wedge 4 constitute one unit and in another embodiment the tightening body 7 and the head 6a constitute one unit. In further embodiments the gap is formed, for example, by means of elevations (or recesses) on the tightening body 7, the shaft end or the wedge 4 or a combination of these. The tightening body 7 need not be entirely plane; it may be formed in various ways in alternative embodiments. In another embodiment the chord of the wedge 4 (the line of intersection between the plane surface of the wedge 4 and the circular segmental surface 4a) is interrupted by a recess, designed to accommodate a part of the cylindrical part 6b of the screw element.

In the preferred embodiment the tightening body 7 includes the flange 7b, but in an alternative embodiment the flange comprises a separate unit (not shown).

Claims

1. Device for anchoring a cylindrical shaft end (lb) in a circular through-opening for the shaft end (lb), such as in a fixing lug (2), the shaft end (lb) having at least one plane chamfer (3) which forms an acute angle with the centre line of the shaft (1) and the anchoring device comprising a wedge element (4) substantially filling a space between the chamfer (3) and the corresponding wall section of the through-opening, the end (4a) of which wedge element is designed to be acted upon by a head (6a) of a screw element (6) arranged on the shaft (1), in order thereby to create the anchorage by pressing in the wedge element (4) characterised in that the device further comprises a tightening body (7) arranged between the head (6a) and the wedge element (4) and designed, by tightening of the screw element (6), to brace against, and be capable of turning somewhat about, a support point (9), arranged on the shaft end (lb) and situated on the opposite side of the screw element (6) to the wedge (4).

2. Device according to claim 1, characterised in that there is also an anchoring device according to claim 1 arranged at a second end of the shaft (1).

3. Device according to either of the preceding claims, characterised in that the distance from the cylindrical part (6b) of the screw element to the support point (9) is greater than the distance to the wedge (4).

4. Device according to any of the preceding claims, characterised in that there are a number of support points (9), which are situated along a line substantially parallel to the chord of the wedge (4).

5. Device according to any of the preceding claims, characterised in that the tightening body (7) extends radially outside the periphery of the shaft (1) and forms a flange (7b).

6. Device according to any of the preceding claims, characterised in that each shaft end (lb) has at least two wedges (4).

7. Device according to any of the preceding claims, characterised in that the bearing surface of the tightening body (7) against the head (6a) of the screw element in the clamped position is substantially perpendicular to the axis of the screw element (6). Device according to any of the preceding claims, characterised in that a further chamfer (8) on the shaft end (lb) forms a space between the chamfer (8), the wedge (4) and the tightening body (7).