IE45234B1 - Joint between mechanical elements - Google Patents

Description

The present invention relates to a friction joint, for connecting first and second mechanical elements, at least one of which has a cylindrical, or polygonal outer surface.

In order to accomplish a joint of the above mentioned type, a number of various designs have previously been used. An example of previously known connecting members, intended to be used in connection with elements having a cylindrical outer surface, is a ring which in co-operation with a body member and a nut member is forced into the outer surface of the embraced cylindrical elements so as to press up a collar to form a seat. However plastic and mechanical deformation of the embraced tubular member is unavoidable. A further example of a previously known joint for tubular elements includes a sealing ring with conical cross-section soldered to the tubular element, under the action of a nut member the ring compresses a drawn copper washer against a seat having a conical contact surface. When a tightened joint is loosened, the sealing washer must be replaced by a new and undeformed washer, before the joint is retightened again. As examples of previously known techniques various types of soldered and welded joints can also be mentioned. Finally, as an example of a previously known joint the type may be mentioned which includes a tubular connection having an external screw thread and being welded to a tubular member, said external screw thread being attachable to a flange member arranged with a corresponding internal screw thread, said flange member being attached to a mechanical element by means of a bolt connection with an 0-ring used as a sealing element between the flange member and a cylindrical surface. The examples referred to above as previous techniques are mainly used for connection of tubular elements having a cylindrical outer surface, but similar joining memberv a:. - also used for connection of bars or axles with a cyli.ifrical outer surface.

For connection of elements having a polygonal outer surface, it is previously known to use tubular elements having a through bore, which in cross-section has a shape corresponding to the element to be connected.

In order to accomplish a locking effect between the tubular element and the -rseed element a screw means has often been used, arranged to press the embraced element against at least one internal side surface of the tubular element. The tuoular element has also often been arranged witii u number of grooves and an outer surface arranged to interact with a conical surface, arranged inside a nut member. When the nut member is rotated and thereoy moved axially in relation to the tubular element, the area of the through bore is gradually reduced whereby an embraced element is locked by the tubular member.

A considerable disadvantage in respect of previously known types of joints is that they are not suitable for accomplishing a jcint between e.g. a machinery part and a bar cr tube element which projects close to the base of a machinery part. A further disadvantage is, that previously known types of joints do not allow for ¢1523-1 _ 4 connection with maximum sealing properties, without mechanical deformation or damage on the connected element. A further important disadvantage is, that it previously has been impossible to ascertain the force of connection of the joint, a feature most desirable in order to optimize the properties of the connected element in relation to tensile forces, and internal pressure forces. Finally, previously known joining merabers based on methods of attachment such as welding or mechanical deformation are eminently unsuitable when the joint is made subject to vibration forces, in which case rupture often has been the result.

The object of the joint according to the present invention is to eliminate the disadvantages set forth above, and further advantages are also gained. The joint according to the present invention is arranged to cooperate with a machine element or other means and together form a means of connection, allowing repeated connection and disconnection of an element, without any changes in the connection properties and without changing or deforming the connected element in any way. Furthermore, maximum connection force can be achieved for various applications, since the joint can be adapted easily to the connected element v/ith regard to said element's tensile strength or deformation properties, a feature of vital importance when used for attachment of tubular elements intended for a gas or fluid flow under high pressure. The force acting against the attached tubular member can thus be related to the wall thickness, the material and the internal pressure applied to said member, whereby the desired maximum connection force can be obtained without any deformation of the connected - 5 element. A further advantage is, that the joint according to the present invention also provides for extremely good sealing properties between the connected element and the element or means in which the joint is arranged, and that these sealing properties are maintained even after repeated connection and disconnection of the attached element, and that the joint is extremely resistant against vibration forces. The joint according to the presejit invention makes it also possible to achieve these desired features with an extremely x ?>.stircted movement of a force producing means arranged to influence integral elements of the joint. A resulting advantage is, that the connection and disconnection operation is simplified, since a tool member co-operates with the force producing means only needs to be moved a restricted distance, which makes it possible to utilize the joint in areas with a restricted possibility to move the tool e.g. in a rotary movement, and also a reduced connection and disconnection time.

According to this invention a frictional joint between a first mechnnix al element having a cylindrical or polygonal surface and a second mechanical element having a bore therein for reception of the first element, the joint being characterized by the provision of a sleeve extending co-axially with the first element and having a nose portion having two convex surfaces and a tail portion, and means for imposing a force on the sleeve so that the convex surfaces of the nose portion contact the surface of the first element and a frusto-conical surface in the bore and the tail portion contacts the surface of the first element.

A number of embodiments of joints according to the present invention are more fully described below with reference to the accompanying drawings in which:Figure 1 is a longitudinally extending cross-section of a first embodiment of a joint according to the present invention, arranged in an untightened position, having a tubular element inserted into the joint.

Figure 2 is a cross-sectional viexv corresponding to Figure 1, showing the joint tightened and connected to the tubular element, Figure 3 is a longitudinally extending cross-section of a second embodiment of a joint according to the present invention arranged in an actuated and connected position, preferably used for application in which the joint is arranged attached to a body of a material having low resistance against plastic deformation, Figure 4 is a cross-sectional view corresponding to Figure 3, in which the body used for housing the joint is arranged in a slightly modified way.

Figure 5 is a cross-sectional view in an enlarged scale of a part of a joint according to the present invention, Figure 6 is a cross-sectional view of a modified embodiment of a contact means being an integral part of the joint.

Figure 7 is a cross-sectional view corresponding to Figure 6 of a further modified contact means, Figure 8 is an end view of the contact means shown in Figure 7, Figure 9 is a cross-sectional view of a further embodiment of a joint according to the present invention.

Figure 10 is a perspective view of an application example for a joint arranged within the scope of the present invention, and -/Figure 11 is a cross-sectional view of a further modified embodiment of a joint within the scope of the present invention.

With reference to the shown embodiments, it should be emphasized, that they are not only suitable for connection of tubular elements, since also elements having a solid cross-section can be connected.

The embodiment disclosed in Figures 1 and 2 includes a sleeve generally h'enominafced 1. Said sleeve 1 includes a nose portion 2, a tail portion 3 which is bow shaped in cross-section and an outwardly directed lug 4. The lug 4 is arranged to interact with a spring ring 5 having a frusto-conical cross-section, surrounding the tail portion 3. A tubular nut member 6, arranged with an external screw thread, is arranged wish a tubular edge portion 7 directed from the forward end portion, said end portion being arranged to transfer an axial movement of the tubular nut member δ when rotated to the spring ring 5, whereby the spring ring 5 is flattened, thus causing a radially inwardly d1’ eoted force against the bow tail portion 3. In th,-? embodiment disclosed in Figures 1 and 2 a body or element 8 is also shown, in which the joint is arranged, and a tubular member 9, intended to be connected to tne body or the element 8 by means of the joint.

Said body or element 8, in which the joint is arranged, also has an interna] frusto-conical surface 10, intended to co-operate with the nose means 2, and a screw threaded portion, for reception of the nut member 6.

The bow shaped inside surface of the tail portion 3 is shown slightly curved or concave, in order to obtain contact first at the outer end portions of said member 3, ι- ο 3 A U w J when the spring ring 5 is flattened. A difference in height is thus achieved between the central portion of said surface and the outer edge portions, indicated in Figure 5 and hereinafter denominated bow height.

The nose portion 2 is defined by three radii, a forward nose radius, an upper radius and a lower radius. When the spring ring is flattened due to the axial movement of the nut member 6 in relation to the element or body 8 surrounding the joint, the tail portion 3 takes up contact against the embraced tubular member 9, whereby said member, together with the joint, is slightly moved axially in direction towards the surrounding element or body 8. The nose means 2 is thus moved into contact with the frusto-conical surface lo and the nose means 2 serves with the upper and lower radii as a sealing element, having contact with the frusto-conical surface 10 and the outside surface of the embraced member respectively. The tail portion 3 is pressed by means of the force from the spring ring 5 to a contact position 2o with the outer surface of the embraced element 9, whereby a friction joint is achieved.

The tail portion 3 has a longitudinally varying cross-section, preferably with the central portion having a larger cross-section than the edge portions.

The cross-section of the tail portion, as well as the bow height, can be calculated using similar calculation formula as used for determination of the deflection of a beam supported at two points separated from each other when applying a predetermined load to a predetermined point between the support points. The force applied to the tail portion 3 is decided by a suitable choice of spring ring 5. By utilizing this method, it is - 9 possible to achieve a complete contact along the entire internal surface of the tail portion against an embraced member 9, and.the contact pressure can also be determined and related to tha plastic deformation properties of said member 9.

In the embodiment shown in Figures 1 and 2 it is regarded as a condition that the body or the element 8, in which the joint is arranged, is manufactured from a material having su. \ tensile properties that the nose portion 2 can tiki: up contact with a conical contact surface 10 arranged in the said body or element 8. In view of the fact that a number of materials are deformed easily at the contact point for the nose portion 2, a modified embodiment is shown in Figure 3. According to this embodiment, an additional part 11 is used, having an internal frusto-conical contact surface intended to interact with the nose portion 2 correspondingly to the way described with reference to the frusto-conical surface 10. The body or element 8, in which the joint is arranged, hag ir. this case been arranged with two frusto-conical contact surfaces, having different angular relationship, against which surfaces the additional part 11 has contact with an outwardly convex surface. As a result, the contact pressure is applied to two separated points and the sealing properties between the additional part 11 and the body or element 8 surrounding the joint is also improved.

A variation of the embodiment shown in Figure 3 is also shown in Figure 4. According to Figure 4 only one frusto-conical contact surface is arranged in the body or the element 8 surrounding the joint. Said embodiment is an example of a preferred embodiment when the body or Ζ f-ί «1 <» 1 fi α -Λ - 10 the element 8 is manufactured from a hard material.

In order to obtain an improved sealing effect between the sleeve 1_and the attached element 9, the sleeve 1_ can advantageously be arranged as shown in Figure 6. Accord5 ing to this embodiment, the sleeve 1_ is arranged with two recesses separated from each other adjacent to the nose portion 2 in the surface facing the connected element 9, which gives an improved sealing effect between the sleeve 1. and the connected element 9.

A further modified embodiment of a sleeve 1. is shown in Figures 7 and S. According to this embodiment, the nose portion 2 and the bow tail portion 3 are arranged as two separate elements, and the bow tail portion 3 is arranged with an axially extending groove. The two elements 2, 3 can be joined together by causing the bow tail portion 3 to take up a reduced diameter under the influence of an applied force, whereby the nose portion 2 can be attached to same by means of fixing members or means arranged in the nose portion 2 and the tail portion 3 respectively. The internal surface of the tail portion 3 has also been arranged with surrounding grooves, which, in previously known way, improve contact and sealing properties against a connected element 9. By arranging the nose portion 2 and the bow tail portion 3 as two separate and with each other interconnectable parts is advantageous in a number of ways, mainly from manufacturing point of view. This method also reduces the stock of part components, since nose portions 2 and tail portions 3 with different properties can be combined.

The above described embodiments have all utilized a spring ring 5 with frusto-conical shape as a force transferring element. However, many other solutions can be used for application of necessary force, e.g. as shown in Figure 9.

According to this embodiment, the nose portion 2 and the tail portion 3 are arranged divided from each other, as previously disclosed with reference to Figures 7 and 8. However, the tail portion 3 is arranged with a frustoconical outer surface, against which a spring acting member 12 co-acting with an internal frusto-conical surface of the pressure appl ;,· ing member 6 is acting, whereby an axial movement of tne last mentioned surface causes the spring acting member 12 to introduce a force acting on the tail portion 3.

Figure 10 is intended to show the advantages achieved in a restricted space e.g. when projecting close to the base of a machine, when using a joint according to the present invention. When utilizing conventional joints or connection means for attachment of e.g. hydraulic pipes to a machine part, a certain distance is always necessary from the machine part to a point where e.g. the pipe can be bent. This distance is considerably reduced when utilizing the joint according to the present invention.

Finally, in Figure 11 a further embodiment is disclosed in which the spring acting member 5, e.g. a spring ring, is arranged with the outer peripheral portion in contact with the surrounding element 8, having the inside peripheral portion in contact with the sleeve 1 at a point located forward of an outwardly directed stop member 4. A force applying means 6 is arranged with the forward edge portion in contact with the sleeve 1, whereby an axially directed movement of the force applying means 6 causes a corresponding movement of the sleeve 1., whereby also the spring member 5 is caused to 43234 apply a radially directed force acting on the sleeve 1. The remaining functions of this embodiment correspond to previously discussed embodiments.

The embodiments described and shown can without any difficulties be modified for attachment of elements having a polygonal outer surface. In this case the sleeve 1 is arranged with inwardly directed slightly curved contact surfaces, arranged in such a way that an open area is created between the contact surfaces corres10 ponding to the cross-sectional area of the element to be attached. The sleeve 1. is dimensioned and designed as set forth with respect to principles applicable for attachment of elements having a circular outer surface. *523 -J

Claims (8)

1. CLAIMS;1. A friction joint between a first mechanical element having a cylindrical or polygonal surface and a second mechanical element having a bore therein for reception of the first element, the joint being characterized by the provision of a sleeve extending coaxially with the first element and having a nose portion having two convex surfaces and s tail portion, and means for imposing a force o:. ohe sleeve so that the convex surfaces of the r.ose portion contact the surface of the first element and a frusto-conical surface in the bore and the tail portion contacts the surface of the first element.

2. A joint according to Claim 1, in which the tail portion is bow-shaped in cross-section and in whieh a predetermined force applied at a predetermined point causes the bow-shaped portion to apply a corresponding force against the outer surface of the first element.

3. A joint according to Claim 1 or 2, in which the force imposing means comprises a spring ring, the peripheral surface of which abuts the peripheral surface of the tail portion, the ring being flattened by application of an axial force to cause axial movement of the sleeve and compression of the tail portion into contact with the surface of the first element.

4. A joint according to any preceding claim, in which the sleeve has at least one concave recess between the nose portion and the tail portion.

5. A joint according to'any preceding claim in which the nose portion and the tail portion are separate but interconnectable parts.

6. A joint according to any preceding claim in which the tail portion has at least one axial slot - 14 therein to facilitate compression.

7. A joint according to any preceding claim in which an additional member having a frusto-conical surface is arranged between the frusto-conical surface on the 5 bore and the nose portion.

8. A joint substantially as herein described with reference to and as shown in the accompanying drawings. F. R. KELLY & CO., AGENTS FOR THE APPLICANTS.