WO2010149848A1

WO2010149848A1 - A method for fastening a joint pin to a structural member, a joint pin, and a joint construction

Info

Publication number: WO2010149848A1
Application number: PCT/FI2010/050515
Authority: WO
Inventors: Kalle Pohjola
Original assignee: Rannikon Konetekniikka Oy
Priority date: 2009-06-25
Filing date: 2010-06-16
Publication date: 2010-12-29
Also published as: IN2012DN00584A; FI20095725A0; FI20095725A

Abstract

In the method, a joint pin (10) is fastened in a removable manner to a first structural member (100), such as a shovel or the supporting part of a shovel in loading, mucking or excavating equipment. The structural member is provided with a conical recess (102) and a threaded fastening hole (104) at the bottom of the recess. The joint pin is provided with a conical fixing piece (14) that matches the recess, and a hole (12) extending in the direction of the longitudinal axis of the joint pin. The fixing piece is fitted in the recess of the first structural member and is fastened in its place by a fastening screw (20), wherein the fixing piece is pressed tightly into the recess. The joint pin is provided with a pin part encircled by an annular bearing (30) placed in a bearing hole (202) in a second structural member (200). The hole of the joint pin has an inner threading for engaging an extraction tool. The largest diameter of the fastening part is larger than the diameter of the pin part, wherein the joint pin to be extracted will remove the bearing (30) fitted around the pin part from the bearing hole (202).

Description

A method for fastening a joint pin to a structural member, a joint pin, and a joint construction

The invention relates to a method for fastening a joint pin to a first structural member in a removable manner. The invention further relates to a joint pin having a first end for fastening to a first structural member and a second end with a pin part, around which a bearing can be fitted. Moreover, the invention relates to a joint construction with a joint pin according to the invention.

Loading, mucking and excavating equipment, such as grabs, often comprise a shovel fixed in an articulated manner to the supporting or suspending member bearing the same. The articulation between the members is usually implemented with a structure, where the first member comprises two parallel plate-like brackets with a hole extending through them. The second member comprises one bracket with a hole, in which an annular bearing is placed. The bearing may be, for example, a sleeve-like slide bearing. The bracket of the second member is placed between the brackets of the first member, and the parts are connected with a joint pin extending through the brackets and the bearing.

A problem with the above-described joint construction is its difficult maintenance. In particular, the bearings of loading, mucking and excavating equipment are exposed to water, dust and dirt as well as subjected to heavy mechanical loading during the use of the equipment. The maintenance of the bearings in working condition requires greasing of the bearing surfaces. In spite of the greasing, the bearings tend to be jammed due to corrosion of the bearing surfaces and entrainment of dust and dirt between the bearing surfaces. The disassembling and maintenance of a jammed joint construction is laborious and may require the cutting off of the brackets.

It is an objective of the invention to provide a new method for fastening a joint pin to a structural member, a joint pin, and a join structure, by means of which it is possible to significantly reduce the drawbacks and disadvantages related to the prior art.

The objectives of the invention are achieved by a method, a joint pin and a joint construction characterized in what will be set forth in the independent claims. Some preferred embodiments of the invention will be presented in the dependent claims. In the method according to the invention, a joint pin is fastened to a first structural member in a removable manner. The first structural member, to which the joint pin is attached, may be, for example, a shovel or a supporting part for a shovel of loading, mucking or excavating equipment, such as a grab. Fastening in a removable manner means that the joint pin can be removed from the structural member intact by using conventional tools without cracking the structures. In the method, a recess and a fastening hole at the bottom of the recess is formed to the first structural member. The cross section of the recess increases from the bottom of the recess towards the mouth of the recess. A fixing piece is formed to the joint pin. The shape of the fixing piece matches the shape of the recess and its cross section increases from the first end towards the second end of the joint pin. The matching shape means that the fixing piece can be inserted in the recess from the direction of the mouth of the recess, and the inserted fixing piece fills the recess substantially in full. Advantageously, the recess and the fixing piece are conical in shape. Further, a through hole extending in the direction of its longitudinal axis is formed to the joint pin. After this, the fixing piece of the joint pin is fitted in the recess of the first structural member, and a fastening screw extending to the fastening hole is inserted in the hole of the joint pin. The joint pin is fixed in its place by tightening the fastening screw, wherein the fixing piece is pressed tightly in the recess and locked in its place. Advantageously, the fastening hole is provided with threads, to which the fastening screw is screwed in.

In an advantageous embodiment of the method according to the invention, the joint pin is fixed in its place in the first structural member through a bearing hole in the second structural member. Advantageously, a bearing is fastened to the joint pin before the joint pin is fastened to the first structural member. The joint pin and the bearing fastened to it are thus inserted as a single unit.

The joint pin according to the invention has a first end for fastening to the first structural member and a second end having a pin part. An annular bearing can be fitted around the pin part. The first end of the joint pin comprises a fixing piece whose cross section increases from the first end towards the second end of the joint pin and which is intended to be fitted in a recess in the first structural member and which matches with the shape of the recess. Advantageously, the fixing piece has a conical shape. Furthermore, the joint pin has a through hole extending in the direction of its longitudinal axis, into which hole the fastening screw to be used for fastening the joint pin is fitted.

In an advantageous embodiment of the joint pin according to the invention, the largest diameter of the fixing piece is greater than the diameter of the pin part, and the interface between the fixing piece and the pin part has an annular edge surface encircling the pin part. Advantageously, said edge surface comprises an outer edge surface on its outer periphery and an inner edge surface limited to the outer surface of the pin part, the outer and inner edge surfaces being set on different levels. The edge surface constitutes a supporting surface, against which the first end surface of the bearing to be placed around the pin part is placed.

In another advantageous embodiment of the joint pin according to the invention, the outer surface of the pin part comprises an encircling groove, and the pin part comprises at least one channel extending from the hole to said groove. By means of the groove and the channel, lubricant can be conveyed through the hole in the pin part to the sliding surface of the bearing to be placed around the pin part.

In another advantageous embodiment of the joint pin according to the invention, the hole comprises an inner thread for engaging an extraction tool.

The joint construction according to the invention comprises a first structural member, a joint pin fastened to the first structural member in a removable manner and comprising a pin part, and an annular bearing fitted around the pin part. Advantageously, the bearing is a rocker bearing composed of two annular bearing races within each other, having a curved sliding surface therebetween. The bearing may also be a conventional sleeve-like sliding bearing, roller bearing or ball bearing. The joint pin comprises a fixing piece whose cross section increases from the first end towards the second end of the joint pin, and a hole extending in the direction of the longitudinal axis of the joint pin. The first structural member comprises a recess which matches the shape of the fixing piece and whose bottom is provided with a fastening hole. Advantageously, the fixing piece and the recess are conical in shape. The fixing piece of the joint pin is fitted in the recess, and a fastening screw extending to the fastening hole is fitted in the hole of the joint pin. The fastening screw keeps the fixing piece of the joint pin tightly in the recess.

An advantageous embodiment of the joint construction according to the invention further comprises a second structural member with a bearing hole in which said bearing is placed. The diameter of the bearing hole is larger than the largest diameter of the fixing piece, which makes it possible to insert the joint pin through the bearing hole.

In another advantageous embodiment of the joint construction according to the invention, the largest diameter of the fixing piece is greater than the diameter of the pin part, and the interface between the fixing piece and the pin part has an annular edge surface encircling the pin part. Advantageously, said edge surface comprises an outer edge surface placed on its outer periphery, and an inner edge surface limited to the outer surface of the pin part, the outer and inner edge surfaces being set on different levels. The bearing comprises a first end surface arranged to be pressed against the edge surface, preferably the outer edge surface of the joint pin.

In a third advantageous embodiment of the joint construction according to the invention, a supporting washer is placed at the end of the pin part, and the bearing has a second end surface arranged to be pressed against the surface of the supporting washer. The supporting washer thus secures that the bearing cannot come off the bearing hole.

In a third advantageous embodiment of the joint construction according to the invention, it is a joint construction in loading, mucking or excavating equipment, such as a grab. The invention has the advantage that it facilitates significantly the maintenance and repair of the joint construction. Thanks to the invention, it is easier to grease and seal the bearing of the joint construction, which extends the service life of the joint construction and reduces the need for maintenance.

Further advantages of the invention include a simple structure and low manufacturing costs.

In the following, the invention will be described in detail. In the description, reference will be made to the accompanying drawings, in which:

Fig. 1 shows, as an example, a joint construction according to the invention in a cross-sectional view.

In Fig. 1 , an example of a joint construction according to the invention is shown in a cross-sectional view. The joint construction according to the invention comprises a joint pin 10 with a first end and a second end. The first end of the joint pin comprises a conical fixing piece 14, by means of which the joint pin is fastened to a first structural member 100. The first structural member 100 comprises a conical recess 102 that matches the shape of the fixing piece 14 of the joint pin. At the end of the recess, there is a fastening hole 104 with a threaded surface. At the second end of the joint pin, there is a cylindrical pin part 16, an annular bearing 30 being fitted around the pin part 16. The bearing shown in Fig. 1 is a sleeve-like sliding bearing, but it is also possible to use roller bearings or ball bearings. The bearing is placed in a bearing hole 202 in a second structural member 200. At the edge closer to the fixing piece, the bearing hole is provided with a lip 204, against which the outer race of the first end surface of the bearing is placed.

The diameter of the conical fixing piece increases from the first end towards the second end of the joint pin. The diameter of the fixing piece is the greatest at the location where the pin part begins. The greatest diameter of the fixing piece is clearly greater than the outer diameter of the pin part, wherein an annular edge surface is formed at the interface of the fixing piece and the pin part, encircling the pin part. At the edge surface, there is an outer edge surface 18a placed at the outer periphery of the edge surface, and an inner edge surface 18b limited to the outer surface of the pin part, the edge surfaces being set on different levels. The outer edge surface is closer to the second end of the joint pin than the inner edge surface 18b, seen in the direction of the axis of the joint pin. A hole 12 is provided in the centre of the joint pin, extending in the direction of its longitudinal axis, and a screw 20 for fastening the joint pin is fitted in the hole. At the second end of the pin part, there is a supporting washer 40 having a through hole for the fastening screw. The edges of the supporting washer extend beyond the area limited by the outer edges of the bearing 30 around the pin part 16. At the edge of the supporting washer, there is a collar 42 protruding from its surface, supported to the outer race of the second end surface of the bearing and the surface of the second structural member 200 around the bearing hole 202.

An encircling groove 24 is provided on the outer surface of the pin part 16, and similarly, a groove 25 is provided on the sliding surface of the bearing 30 against the surface of the pin part. These grooves, placed against each other, form an annular cavity encircling the pin part. From the hole 12, radial channels 26 extend into the groove 24. In the centre of the fastening screw, a lubrication hole 28 extends in the direction of its longitudinal axis, the second end of the hole opening into a recess in the head 22 of the fastening screw. The end of the lubrication hole is closed with a removable plug 29. From the first end of the lubrication hole, channels 27 extend radially, opening at the outer surface of the fastening screw. Via the channels 27 of the fastening screw and the channels 26 of the pin part, a flow path is thus opened from the lubrication hole 28 into the groove 24. Via this flow path, lubrication oil can be supplied into the clearance between the outer surface of the pin part and the sliding surface of the bearing placed against it.

The joint construction is assembled by fitting the fixing piece 14 of the joint pin 10 into the recess 102 of the first structural member 100. The largest outer diameter of the fixing piece is smaller than the inner diameter of the bearing hole 202 of the second structural member 200, so the fixing piece can be inserted in the recess through the bearing hole. After this, the bearing 30 is placed around the pin part 16 in such a way that the first end surface of the bearing abuts the lip 204 and the outer edge surface 18a of the fixing piece. The assembly can also be accomplished by first placing the bearing around the pin part of the loose joint pin, after which the fixing piece of the joint pin is inserted through the bearing hole into the recess of the first structural member. At the same time, the bearing is set in its place in the bearing hole. Finally, the supporting washer is fitted in its place against the end surface of the pin part, and the fastening screw is inserted in the hole in the joint pin. When the fastening screw is screwed in, its threaded end is placed in the threads of the fastening hole 104, wherein the head 22 of the fastening screw moves towards the fixing piece. The supporting washer is thus pressed between the head of the fastening screw and the end surface of the pin part. At the same time, the fixing piece is pressed tightly into the recess 102 and locked in its place. Friction effective between the wall of the fixing piece and the wall of the recess prevents the joint pin from rotating in the recess. The joint pin 10 is thus fixed in a stationary manner in the first structural member 100. The stationary fixing means that the joint pin cannot come off the recess and cannot rotate in the recess.

The collar of the supporting washer is pressed against the second end surface of the bearing, preventing the bearing from coming off the bearing hole. In Figure 1 , the supporting washer has such a size that it will cover one bearing under it. The supporting washer may also be so large in size that it will cover two or more bearings under it.

The joint construction is disassembled in a reverse order by removing the fastening screw 20 and the supporting washer 40 supported by it. The joint pin can then be pulled out of the recess 102 through the bearing hole 202. When pulling out the joint pin, the first and second edge surfaces 18a, 18b are pressed against the first end surface of the bearing, pulling out the bearing from the bearing hole 202. To facilitate the removal of the joint pin, an inner threading 32 is provided at the end of the hole 12, where an extraction tool or a so-called extractor can be threaded in. By means of the extractor, the joint pins can be engaged firmly with the extraction tool, so that the bearing and the joint pin, fitted tightly in place, can be easily removed. The fixing piece of the joint pin shown in Fig. 1 , and the recess of the first structural member having a matching shape, are conical. However, the fixing piece and the recess do not need to be conical in shape, but other shapes are possible as well. It is essential for the shape of the fixing piece that its cross section in the direction of the normal of the axis of the joint pin increases from the first end towards the second end of the joint pin. Consequently, the fixing piece may have the shape of, for example, a truncated pyramid or a truncated wedge. By changing the cross section of the fixing piece, it is secured that the fixing piece can be inserted in the recess and removed from the recess without frictional forces effective on the contact surfaces.

In Fig. 1 , the fastening hole 104 at the bottom of the first structural member is provided with threads, in which the fastening screw 20 is engaged. The fastening of the joint pin can also be implemented by extending the fastening hole through the first structural member, the second end of the fastening hole opening at the outer surface of the structural member. A sufficiently long fastening screw is inserted in the fastening hole so that its threaded end will extend via the second end of the fastening hole outside the first structural member. A nut is screwed on this end of the fastening screw. In this advantageous embodiment of the invention, the fastening hole itself may be unthreaded.

In some joint constructions, it is possible to use two joint pins fastened to the same structural member on the same imaginary line in such a way that their pin parts point away from each other. The structural member is thus provided with two recesses for the fixing pieces of the joint pins, and it can be provided with one fastening hole extending through the structural member, to extend from the bottom of the first recess to the bottom of the second recess. Both joint pins can be fastened in their place in the structural member with a single fastening screw or threaded bar fitted in the fastening hole and extending through both of the joint pins.

The joint construction according to the invention may be a joint construction between any two structural members fastened to each other in an articulated manner. Thanks to the easy maintenance of the joint construction, it is particularly suitable for use in such equipment comprising joint constructions which is exposed to moisture, dirt, dust, and heavy mechanical loading during its use, and which is therefore in great need of maintenance. Such joint constructions include, for example, the joint constructions of loading, mucking and excavating equipment, such as grabs. The first and second structural members described in the above description may thus be parts of loading, mucking and excavating equipment, such as grabs, which are fastened to each other in an articulated manner by means of the joint construction according to the invention.

Some advantageous embodiments of the method, the joint pin and the joint construction according the invention have been described above. The invention is not restricted to solutions described above, but the inventive idea can be applied in numerous ways within the scope defined by the claims.

Claims

1. A method for fastening a joint pin (10) to a first structural member (100) in a removable manner, characterized in that the method comprises: - forming to the first structural member a recess (102) whose cross section increases from the bottom of the recess towards the mouth of the recess, and a fastening hole (104) at the bottom of the recess;

- forming to the joint pin a fixing piece (14) which matches the shape of the recess and whose cross section increases from the first end towards the second end of the joint pin, and a through hole (12) extending in the direction of the longitudinal axis of the joint pin;

- fitting the fixing piece of the joint pin in the recess of the first structural member;

- inserting a fastening screw (20) extending to the fastening hole (104) in the hole (12) of the joint pin; and - fastening the joint pin in its place by tightening the fastening screw.

2. The method according to claim 1 , characterized in that a conical recess (102) is formed to the first structural member (100) and a conical fixing piece (14) is formed to the joint pin (10).

3. The method according to claim 1 or 2, characterized in that threads are formed to the fastening hole (104) and the fastening screw (20) is engaged in said threads.

4. The method according to any of the claims 1 to 3, characterized in that the joint pin (10) is inserted in its place in the first structural member (100) through a bearing hole (202) in the second structural member (200).

5. The method according to any of the claims 1 to 4, characterized in that a bearing (30) is fastened to the joint pin (10) before the joint pin is fastened to the first structural member.

6. The method according to any of the claims 1 to 5, characterized in that the joint pin (10) is fastened to the first structural member (100) in a stationary manner.

7. A joint pin (10) having a first end for fastening to a first structural member (100) and a second end with a pin part (16), around which a bearing (30) can be fitted, characterized in that at the first end there is a fixing piece (14) whose cross section increases from the first end towards the second end of the joint pin and which can be fitted in a recess (102) provided in the first structural member and matching with the shape of the fixing piece, and the joint pin comprises a hole (12) extending in the direction of its longitudinal axis, for a fastening screw (20) to go through.

8. The joint pin (10) according to claim 7, characterized in that the fixing piece (14) is conical in shape.

9. The joint pin (10) according to claim 7 or 8, characterized in that the largest diameter of the fixing piece (14) is larger than the diameter of the pin part (16), and the interface between the fixing piece and the pin part is provided with an annular edge surface encircling the pin part.

10. The joint pin (10) according to claim 9, characterized in that said edge surface comprises an outer edge surface (18a) placed on its outer periphery, and an inner edge surface (18b) limited to the outer surface of the pin part (16), the outer and inner edge surfaces being set on different levels.

11. The joint pin (10) according to any of the claims 7 to 10, characterized in that the outer surface of the pin part (16) comprises an encircling groove (24), and the pin part comprises at least one channel (26) from the hole (12) to said groove.

12. The joint pin (10) according to any of the claims 7 to 11 , characterized in that the hole (12) comprises an inner thread (32) for engaging an extraction tool.

13. A joint construction comprising a first structural member (100), a joint pin (10) fastened to the first structural member in a removable manner and having a pin part (16), and an annular bearing (30) fitted around the pin part, characterized in that in the joint pin (10) there is a fixing piece (14) whose cross section increases from the first end towards the second end of the joint pin, and a hole (12) extending in the direction of the longitudinal axis of the joint pin, and in the first structural member there is a recess (102) which matches the shape of the fixing piece and whose bottom is provided with a fastening hole (104), wherein the fixing piece of the joint pin is fitted in the recess, and a fastening screw (20) extending to the fastening hole (12) is fitted in the hole of the joint pin.

14. The joint construction according to claim 13, characterized in that the fixing piece (14) and the recess (102) are conical in shape.

15. The joint construction according to claim 13 or 14, characterized in that it further comprises a second structural member (200) having a bearing hole (202), in which said bearing (30) is placed, the diameter of the bearing hole being larger than the largest diameter of the fixing piece (14).

16. The joint construction according to any of the claims 13 to 15, characterized in that the largest diameter of the fixing piece (14) is larger than the diameter of the pin part (16), and at the interface between the fixing piece and the pin part there is an annular edge surface encircling the pin part.

17. The joint construction according to claim 16, characterized in that said edge surface comprises an outer edge surface (18a) placed on its outer periphery, and an inner edge surface (18b) limited to the outer surface of the pin part (16), the outer and inner edge surfaces being set on different levels.

18. The joint construction according to claim 16 or 17, characterized in that the bearing (30) comprises a first end surface which is arranged to be pressed against the edge surface, preferably the outer edge surface (18a), of the joint pin.

19. The joint construction according to any of the claims 13 to 18, characterized in that a supporting washer (40) is provided at the end of the pin part (16), and the bearing (30) has a second end surface arranged to be pressed against the surface of the supporting washer.

20. The joint construction according to any of the claims 13 to 19, characterized in that said bearing (30) is a rocker bearing.

21. The joint construction according to any of the claims 13 to 19, characterized in that said bearing (30) is a sliding, roller or ball bearing.

22. The joint construction according to any of the claims 13 to 21, characterized in that the joint pin (10) is fastened to the first structural member (100) in a stationary manner.

23. The joint construction according to any of the claims 12 to 20, characterized in that it is a joint construction in loading, mucking, or excavating equipment, such as a grab.