Chain link and method for producing chain link

Abstract

The invention relates to a chain link (1) for a link chain (2), the chain link (1) having two legs (4, 5) which run parallel to one another and which are connected to one another at the ends by means of arches (6, 7). Each of the legs (4, 5) and the arch (6, 7) of the chain link (1) has a circular cross-section (8, 9, 10, 11), the cross-sectional area (8, 9) of the legs (4, 5) being smaller than the cross-sectional area (10, 11) of the arch (6, 7). The invention relates to a method for producing a chain link (1) by means of radial forging, comprising the following steps: providing a profiled bar (18), said profiled bar (18) being made of a steel material; inserting the profiled bar (18) into a radial forging machine (24) and carrying out radial forging by reducing the diameter (D18) of the profiled bar (18) length by length in such a way that the profiled bar (18) is axially stretched over the forging length, the diameter (D18) being reduced at least in the region of the subsequent legs (4, 5); the radially forged chain link semi-finished product (19) is removed and formed into a chain link (1), and the end face (23) of the formed chain link (1) is welded.

Description

Technical Field

[0001] The invention relates to a chain link for an endless chain according to the features of patent claim 1 .

[0002] The invention also relates to a method for producing a chain link for an endless chain according to the features of patent claim 7 . Background Art

[0003] The mentioned endless chains are used in particular in the mining industry, in particular in underground mining. The endless chains need to have a high strength in order to be able to transmit the motion energy to the mining equipment, such as planers or conveyor chains. In such chain drives, the chain is driven by sprockets, in particular on the upper and lower branches.

[0004] For this purpose, the endless chain consists of horizontal segments and vertical segments, wherein the horizontal segments extend substantially horizontally in the installed state and the vertical segments extend substantially vertically in the installed state. The horizontal segments and the vertical segments are each designed individually as chain links, in particular as annular chain links. For this purpose, they each have two parallel legs. These legs are connected at their ends by corresponding arches. The horizontal segments and the vertical segments are locked together in the arches. During use, the chain is subjected to not only the tensile forces to be transmitted but also, in particular, abrasive wear.

[0005] Reducing the cross-sectional area of ​​the legs while keeping the cross-sectional area of ​​the arch unchanged to reduce the deadweight and size of the endless chain is known in the prior art, for example, as disclosed in DE 103 48 491 B3. For this purpose, the chain link in question is implemented as a flat chain link with flat legs by a forging process. Summary of the invention

[0006] The object of the present invention is to provide a chain link which is optimized and improved compared to the prior art with regard to its own weight and the tensile forces to be transmitted.

[0007] The above-mentioned object is achieved by a chain link according to the features of patent claim 1 .

[0008] A further object of the present invention is to disclose a production method with which chain links can be produced with good shaping freedom and improved material organization.

[0009] This object is achieved according to the invention by a method for producing a chain link according to the features of patent claim 7 .

[0010] Advantageous configuration variants of the invention are described in the dependent claims.

[0011] The chain link according to the invention is part of an endless chain, which can also be referred to as a conveyor chain or flat endless chain and is used in particular in the mining industry. The chain link has two legs extending parallel to one another, wherein the legs are connected to one another at the ends by corresponding arches.

[0012] The legs and the arched member of the chain link each have a circular cross section, wherein the cross-sectional area of ​​the legs is smaller than the cross-sectional area of ​​the arched member.

[0013] By making the cross-sectional area of ​​the legs smaller than the cross-sectional area of ​​the arch, it is firstly achieved that the chain link is lighter than a comparable chain link with the same circumferential cross-sectional area.

[0014] The tensile forces to be transmitted are not affected by the reduced cross-sectional area in the legs. The cross-sectional area of ​​the arches therefore makes it possible to provide the entire tensile force to be transmitted. Due to the low deadweight of the chain, the wear of the chain formed by the chain links during operation is also reduced. By making the cross-sectional area smaller, in particular in the region of the legs, the material expenditure required for producing the chain can be saved, which also reduces the material costs.

[0015] According to the invention, the chain links are now distinguished by the fact that they are produced by radial forging (also called rotary forging or longitudinal forging). Radial forging is essentially an open die forging in which the cross section of the workpiece is reduced in the deformation region using usually 3 or 4 counter-rotating forging dies or punches which are arranged radially around the longitudinal axis of the workpiece in a plane perpendicular to the longitudinal axis of the workpiece. In this process, the workpiece is rotated about its own longitudinal axis between the individual punch impacts. Compared to the production of chain links by means of conventional forging processes in which the workpiece is forged between a flat upper forging die and a flat lower forging die, radial forging has two major advantages:

[0016] - Low ductility and difficult to deform steels and alloys can be forged due to the good tension and extension of the metal in the deformation zone.

[0017] - Avoid cracks or breaks on the material surface by radially arranging the punches.

[0018] Furthermore, radial forging reduces the cross-section of the chain link blank, in particular in the region of the legs, which results in a longitudinal deformation of the chain link blank in the deformation region in the longitudinal direction of the chain link blank. This in turn results in a longitudinally oriented material structure in the deformation region. It has been shown that a longitudinally oriented material structure increases the load-bearing capacity of the chain link, in particular the legs in the longitudinal direction of the chain link, when tensile forces are applied to the chain. Furthermore, the rotationally symmetrical shape of the molded chain link blank can avoid errors when inserting the bending device.

[0019] According to the invention, although a semi-finished chain link with a circular cross section is obtained during the manufacturing process, the surface of the semi-finished chain link presents minimal irregularities due to the radial forging process. Therefore, the chain links manufactured by the radial forging process can be clearly distinguished from chain links manufactured by other processes by their material structure and surface characteristics.

[0020] Radial forging is performed during axial feeding of the chain link blank. Thus, during the radial forging process, the chain link blank (preferably a profile rod) is moved in its axial direction relative to the forging die. The forging process itself leads to a reduction in the diameter of the chain link blank, which results in a longitudinal deformation of the chain link blank in its axial direction. Length sections (e.g. the later legs of the chain link) can be formed by axial feeding of the chain link blank. Radial forging during axial feeding results in a uniform and longitudinally oriented material structure in the deformation region of the chain link blank. In particular, a uniform fiber orientation is formed in the axial direction. The fiber orientation is a structural metallographic property, i.e. the row-like arrangement of the grains or the grain boundaries and inclusions contained in the primary structure. This structure has been shown to be beneficial to the load-bearing capacity of the deformation region when subjected to tension in the axial direction, because the fiber orientation is consistent with the main linear flow in the direction of tension.

[0021] If the deformation region is the leg of the chain link after the semi-finished chain link is formed into a chain link, when a tensile force is applied to the chain link in the longitudinal direction of the chain, the load-bearing capacity of the leg oriented in the longitudinal direction of the chain will increase. This material structure is significantly different from the material structure of the known chain link.

[0022] Preferably, the transition region from the cross section of the leg to the cross section of the arch begins at the respective end of the leg. The transition region can also be partially located in the region of the leg. In particular, the cross section of the transition region in its longitudinal direction is implemented as a circle.

[0023] In particular, the diameter of the leg is 5% to 15% smaller than the diameter of the arch, preferably 9% to 11% smaller. It has been shown that with these diameter ratios, the advantageous longitudinally oriented material structure produced by radial forging is formed over the entire cross section of the leg. With other diameter ratios, however, the advantageous material structure can only be formed, for example, at the outer edge of the leg. These diameter ratios therefore represent the optimum load-bearing capacity of the chain link or leg in the longitudinal direction of the chain link.

[0024] Furthermore, in a side view in the plane of the central longitudinal axis, the inner and outer contours of the chain link preferably have a circumferentially continuous ellipse. This ellipse is characterized by two mutually parallel sides and a semicircular configuration of the ends connecting the sides. The ellipse of the inner and outer contours is not interrupted at any point by depressions, lintels, shoulders, stepped shoulders, bevels or the like. This elliptical embodiment has proven to be particularly advantageous for the distribution of tension forces and the flow of forces within the chain link.

[0025] The method according to the invention is used to manufacture a chain link for an endless chain. The chain link has two legs extending parallel to one another, which are connected to one another at the ends by an arch. The legs and the arch of the chain link are each designed to be circular in cross section, wherein the cross-sectional area of ​​the legs is smaller than the cross-sectional area of ​​the arch. The chain link is manufactured by radial forging in the following method steps:

[0026] Providing a profile bar, wherein the profile bar is made of a steel material;

[0027] Inserting the profile rod into a radial forging machine and radially forging it by reducing its diameter lengthwise so that the profile rod is axially stretched over the forging length, wherein the diameter is reduced in the region of the subsequent leg;

[0028] Preferably, the profile rod is fed axially during the radial forging process to form the length section of the later leg;

[0029] The radially forged chain link semi-finished product is taken out, formed into a chain link, and the end faces of the formed chain link are welded.

[0030] One of the basic advantages of the invention is the increased freedom of shaping, since the cross-section at the arch to be produced later and the cross-section at the leg to be produced later can be produced individually, i.e. with a high degree of freedom of shaping. Since no material needs to be removed from the length sections of the produced chain link with a smaller cross-sectional area, the material investment for producing each chain link is lower.

[0031] The reduction in the cross-section of the chain link blank leads to a longitudinal deformation of the chain link blank in the deformation region, which in turn produces a longitudinally oriented material structure. As has been shown, this is a further essential advantage of the invention, since the longitudinally oriented structure increases the load-bearing capacity of the chain link, in particular the legs in the longitudinal direction of the chain. Furthermore, the rotationally symmetrical shape of the molded chain link blank makes it possible to avoid errors when inserting the bending device.

[0032] In radial forging, pressure is repeatedly applied to the workpiece by a plurality of punches arranged around the axis of the workpiece.

[0033] According to the invention, the workpiece is a profile rod made of a steel material. The length of the profile rod is shorter than the continuous length of the chain link to be produced later. The profile rod is designed to be particularly strong and is particularly preferably made of a hardenable steel material. The cross section of the profile rod is preferably circular.

[0034] The provided profile rod is clamped at both ends or one side in a radial forging machine so that the machine can rotate the profile rod along the central longitudinal axis of the profile rod and move the profile rod forward and backward in the axial direction. Then, the punch arranged radially around the profile rod applies pressure to the specified length section of the profile rod. Then, the profile rod rotates around its own axis and the punch applies pressure to the profile rod again. This reduces the cross-sectional area of ​​the profile rod in the forged length section and axially stretches the profile rod in the deformation area. This method is repeated until the relevant length section of the profile rod reaches a predetermined diameter. According to the present invention, at least the cross-sectional area in the subsequent leg area is reduced. The reduction can also be performed for the subsequent arch area. After the radial forging process is completed, a rotationally symmetrical chain link semi-finished product is manufactured from the profile rod by forming. The length of the chain link semi-finished product is basically consistent with the continuous length of the chain link to be manufactured. The length section of the chain link semi-finished product in the subsequent arch area and the length section of the chain link semi-finished product in the subsequent chain link leg area are both designed to be circular.

[0035] The semi-finished chain link is then removed from the radial forging machine and formed into a chain link. The two end faces are pressed together by a forming process and welded. For this purpose, laser welding or resistance welding can be performed, for example. Alternatively, a friction welding process can also be performed.

[0036] The length sections with a smaller cross-sectional area form the legs of the chain link, and the length sections with a relatively larger cross-sectional area form the arches.

[0037] In this case, the cross-sectional area of ​​the at least one arch preferably corresponds to the cross-sectional area of ​​the profile rod.

[0038] Preferably, during the radial forging, a reduction is also carried out on at least one length section of the subsequent arch.

[0039] In particular, the semi-finished chain link has a transition region between the subsequent arch and the length section of the leg. This transition region preferably accounts for 3% to 10%, particularly preferably 4% to 7% of the total length of the semi-finished chain link. These proportions have proven to be particularly advantageous for the force flow and tension force distribution within the chain link.

[0040] It is further preferred that the welding end face of the unformed chain link is located in the leg region. In particular, the profile rod is radially forged in the hot or semi-hot state. Particularly preferably, the chain link semi-finished product can also be formed into the corresponding chain link in the hot state. It is also conceivable to carry out the radial forging in the cold state or at room temperature.

[0041] Optionally, it is also conceivable to temper the formed and welded chain links. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Other advantages, features and characteristics of the present invention are the subject of the following description. Preferred design variants are shown in the drawings. These drawings help to simplify the understanding of the present invention.

[0043] In the attached picture:

[0044] Figure 1 is a top view of a portion of an endless chain having a chain link according to the invention;

[0045] Figure 2 is a top view of a chain link according to the present invention;

[0046] Figure 3 yes Figure 2 A cross-sectional view of a chain link according to the present invention, with section line AA passing through it;

[0047] Figure 4 yes Figure 2 A cross-sectional view of a chain link according to the present invention with section line BB passing through it;

[0048] Figure 5 is a side view of the profile rod;

[0049] Figure 6 It is a side view of the semi-finished chain link;

[0050] Figure 7 is a side view of a radial forging machine with a clamped profile rod;

[0051] Figure 8 Is a radial forging machine based on Figure 7 Section view of the CC section line;

[0052] Fig. 9 is a sectional view of an alternative embodiment variant of a radial forging machine.

[0053] In the drawings, the same reference numerals are used for the same or similar objects even if a repeated description is omitted for the sake of simplicity. DETAILED DESCRIPTION

[0054] Figure 1 A top view of a chain link 1 according to the invention is shown as a partial section of an endless chain 2. The chain link 1 is designed here as a horizontal segment. Vertical segments 3 connect the segments 1, wherein the vertical segments 3 are produced in a different way. Further chain links 1 in the form of horizontal segments to be added to the right and left side of the drawing plane, and further vertical segments 3 thereafter, and so on, are not shown in detail.

[0055] Figure 2 A detailed top view of a chain link 1 according to the invention is shown. The chain link 1 has two legs 4, 5 extending parallel to one another and connected to one another at the ends by arches 6, 7. Figure 4 , the legs 4, 5 have cross sections 8, 9, which are each designed to be circular. Figure 3 , the arches 6, 7 also have cross sections 10, 11, which are also designed to be circular. The cross-sectional areas 8, 9 of the legs 4, 5 are smaller than the cross-sectional areas 10, 11 of the arches 6, 7. At the ends 12, 13 of the legs 4, 5, respectively, transition areas 14, 15 extend toward the arches 6, 7. The transition areas 14, 15 are also designed to extend in a circular shape. The transition areas 14, 15 extend from the ends 12, 13 of the legs 4, 5, respectively, at an angle a greater than 0 degrees to less than 45 degrees, so that the legs 4, 5 merge into the arches 6, 7.

[0056] The inner contour 16 and the outer contour 17 of the chain link 1 are in the form of a continuous ellipse which is not interrupted at any point by depressions, lintels, shoulders, stepped shoulders, chamfers or the like.

[0057] Figure 4 The diameters D4 and D5 of the legs 4 and 5 shown in FIG. Figure 3 The diameter D6, D7 of the arches 6, 7 shown in FIG. 4 is 4 to 6 mm smaller. Furthermore, the diameter D4, D5 of the legs 4, 5 is 9% to 11% smaller than the diameter D6, D7 of the arches 6, 7.

[0058] Figure 5 A circular and rotationally symmetrical profile rod 18 with a diameter D18 is shown.

[0059] Figure 6 A chain link blank 19 is shown, which is made from a radially forged profile rod 18. The chain link blank 19 has two length sections 20, whose diameter D20 corresponds to the diameter D18 of the profile rod 18, but can also be smaller. The length sections 20 form the region of the arches 6, 7 behind the chain link 1. The diameter D20 of the length sections 20 therefore corresponds to the diameters D6, D7 of the arches 6, 7.

[0060] Furthermore, the length section 21 of the chain link blank 19 corresponds to the region of the later legs 4 , 5 . The diameter D21 of the length section 21 is therefore equal to the diameter D4 , D5 of the legs 4 , 5 .

[0061] A transition region 22 is arranged between the length sections 20 and 21 . This corresponds approximately to the transition regions 14 , 15 downstream of the chain link 1 .

[0062] The chain link blanks 19 are connected with their end faces 23 to form the chain link 1 .

[0063] Figure 7 A simplified illustration of a radial forging machine 24 is shown in which a profile rod 18 is arranged. The profile rod 18 is clamped at its ends in the radial forging machine 24 by means of clamps 25. The profile rod 18 can be rotated about its longitudinal axis and can also be moved forward and backward in the axial direction by means of the clamps 25. Counter-rotating punches 26 are arranged radially around the profile rod 18. This is particularly useful in Figure 8 As can be seen in FIG. 1 , the profile rod 18 is pressed by the punch 26 so that it is stretched in the axial direction. Thus, in the area where the punch 26 is working, the cross-sectional area 27 of the profile rod 18 is reduced. Figure 7 By axially moving the profile rod 18 in the left and right directions of the plane of the drawing, the entire profile rod 18 can be clamped by the punch 26 and forged.

[0064] Fig. 9 An alternative embodiment variant of a radial forging machine 24 with three punches 26 is shown.

[0065] Reference numerals list

[0066] 1-Chain link

[0067] 2-chain

[0068] 3-Vertical Segment

[0069] 4- Legs

[0070] 5- Legs

[0071] 6-Arch

[0072] 7-Arch

[0073] Cross section of 8-4

[0074] Cross section of 9-5

[0075] 10-6 cross section

[0076] Cross section of 11-7

[0077] 12-4 end

[0078] 13-5 end

[0079] 14- Transition Area

[0080] 15- Transition Area

[0081] 16-Inner contour line

[0082] 17-Outer contour line

[0083] 18- Profile rod

[0084] 19-Chain link semi-finished product

[0085] 20-Length segment

[0086] 21-Length segment

[0087] 22- Transition Area

[0088] 23-end face

[0089] 24-Radial forging machine

[0090] 25-Clamp

[0091] 26-Punch

[0092] Cross section of 27-18

[0093] D4-4 diameter

[0094] D5-5 diameter

[0095] D6-6 diameter

[0096] D7-7 diameter

[0097] D18-18 diameter

[0098] D20-20 diameter

[0099] D21-21 diameter

[0100] a-14, 15 angle

Claims

1. A chain link (1) for an endless chain (2), wherein: The chain link (1) comprises two legs (4, 5) extending parallel to each other, the legs are connected to each other at the ends by an arch (6, 7), and the legs (4, 5) and the arch (6, 7) of the chain link (1) are both designed to be circular in cross-section (8, 9, 10, 11), wherein the cross-sectional area (8, 9) of the legs (4, 5) is smaller than the cross-sectional area (10, 11) of the arch (6, 7), and the chain link (1) is manufactured by radial forging.

2. The chain link (1) according to claim 1, characterized in that A transition region (14, 15) from the cross section (8, 9) of the legs (4, 5) to the cross section (10, 11) of the arch (6, 7) begins at the respective end (12, 13) of the legs (4, 5).

3. The chain link (1) according to claim 2, characterized in that The transition region (14, 15) is designed to be circular in cross section in its longitudinal direction.

4. The chain link (1) according to any one of claims 1 to 3, characterized in that The diameter (D4, D5) of the legs (4, 5) is 5% to 15% smaller, preferably 9% to 11% smaller, than the diameter (D6, D7) of the arches (6, 7).

5. The chain link (1) according to any one of claims 1 to 4, characterized in that In a side view of the central longitudinal axis plane, the inner contour line (16) and the outer contour line (17) of the chain link (1) are circumferentially continuous ellipses.

6. The chain link (1) according to any one of claims 1 to 5, characterized in that The radial forging is performed during axial feed.

7. A method for producing a chain link (1) according to claim 1, characterized in that The following method steps: A profile bar (18) is provided, wherein the profile bar (18) is made of a steel material, The profile rod (18) is inserted into a radial forging machine (24) and radially forged by reducing the diameter (D18) of the profile rod (18) in sections, so that the profile rod (18) is axially stretched over the forged length, wherein the diameter (D18) is reduced at least in the region of the subsequent legs (4, 5), The radially forged chain link semi-finished product (19) is taken out, formed into a chain link (1), and the end surface (23) of the formed chain link (1) is welded.

8. The method according to claim 7, characterized in that The diameter (D18) of the profile rod (18) corresponds to the diameter (D6, D7) of at least one arch (6, 7).

9. The method according to claim 7 or 8, characterized in that: During radial forging, the diameter (D18) of at least one length section (21) of the subsequent leg (4, 5) is reduced.

10. The method according to any one of claims 7 to 9, characterized in that The transition region (22) between the subsequent arch (6, 7) and the length section (20, 21) of the subsequent leg (4, 5) of the semi-finished chain link (19) accounts for 3% to 10%, preferably 4% to 7% of the total length (L19) of the semi-finished chain link (19).

11. The method according to any one of claims 7 to 10, characterized in that The welded end faces (23) of the formed chain links (1) are located in the region of the legs (4, 5).

12. The method according to any one of claims 7 to 11, characterized in that The profile rod (18) is radially forged in a cold, hot or semi-hot state.

13. The method according to any one of claims 7 to 12, characterized in that The formed and welded chain link (1) undergoes a tempering treatment.

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