CHAIN ​​AND ARRANGEMENT OF A CHAIN ​​WITH A SPROCKET

Description

[0001] The invention relates to a chain having the features of the preamble of claim 1.

[0002] A chain consists of a multitude of interlocking chain links. The chain links have two opposing, usually parallel, legs and a connecting loop, so that each chain link forms a closed loop. These chains are usually made of steel.

[0003] A chain can be used for a wide variety of applications. Chains are subjected to tensile loads and are used, for example, to secure objects or as a drive in a conveyor. A conveyor typically consists of two parallel chains, with stays between the two chains that push and move material resting on a track, such as a conveyor trough. The chains used here are endless chains; the chains are deflected at the ends of the track.

[0004] To apply a tensile force to the chain, a sprocket is used, which has at least one chain pocket. The chain pocket is designed to correspond to a first chain link of the chain, so that there is positive contact in the direction of tension between the chain link and the chain pocket. This contact moves the chain link in the direction of tension, exerting a tensile force on the chain. This first chain link is usually the horizontal link of a chain formed by horizontal and vertical chain links, as is common for conveyors, for example.

[0005] The positive contact between the chain pocket and the chain link usually occurs in the bow area, specifically in the outward-facing area of ​​the front face of the bow facing in the pitch direction (longitudinal direction of the chain link). The force is transferred from the chain pocket to the chain link by a compressive force applied by the chain pocket to the chain link.

[0006] A known design of such a chain link is addressed in DE 196 10 935, DE 198 31 994, and DE 41 24 788. The chain type mentioned in these disclosures is also referred to as an arrow-tooth chain. The bow of an arrow-tooth chain link is designed such that it is divided into three parts along its extension direction, with which it connects the two legs: It has two pressure sections spaced apart from one another in the bow extension—thus essentially in the chain link width direction—and an intermediate section connecting the pressure sections. The pressure sections of the chain link serve as contact surfaces between the chain link and the chain pocket for transmitting the driving forces and can therefore also be referred to as output surfaces. A similar chain is shown in US 5435431 B1.

[0007] The aim of the aforementioned herringbone tooth chains is to make the pressure sections straight, at least in the direction of bow extension, in order to achieve a large-area contact between the chain pocket and the horizontal chain link as a contact surface and thus to keep the surface pressure in this area low.

[0008] For self-centering, the pressure sections are positioned in an arrow-shaped manner relative to the chain link width direction, so that the intermediate section is curved at least in sections.

[0009] The problem with these herringbone chains is that the desired, designed, large-area contact is not actually achieved during operation due to local load-induced deformations. Rather, such chains tend to exhibit edge wear at the edges of the pressure sections, resulting in excessive wear of the chain link and the chain pocket, typically resulting in a ducktail.

[0010] Another type of chain shape is disclosed in DE 10 2010 061 264 A1 and US 2012 / 0065012 A1. These also provide pressure surfaces on the curves of the chain links. However, the arrow shape is less pronounced. The pressure surfaces are straight.

[0011] Against this background, the object of the invention is to further develop a corresponding chain with a described chain link so that it enables safe and long-lasting operation even under load in practice. A further object of the invention is to provide an arrangement of such a chain and a sprocket.

[0012] This object is achieved by a generic chain mentioned at the outset with the features of claim 1. The arrangement-related object is achieved by an arrangement according to claim 11. Advantageous embodiments emerge from the dependent claims and the description.

[0013] The core of the invention is to design the end face of at least one bow, typically both bows, in the pressure sections with a convex curve in the direction of the bow extension. This means that the contact surface is structurally designed as a point load. However, due to the flattening deformation of the pressure section in the chain pocket due to the point load during operation, the actual contact surface is larger than in the unloaded state; the deformation increases the radius of curvature of the pressure sections. The higher the load on the chain, the more the pressure section deforms and thus offers a larger contact surface, which in turn reduces the surface pressure. The pressure section thus provides an adaptive contact surface depending on the load and is no longer a complete contact surface from a structural point of view. Rather, usually only a part of the pressure section is the contact surface.

[0014] In order to provide an optimal load-dependent contact area size while simultaneously maintaining the local surface pressure at an acceptable level, the radius of curvature of the compression sections in the direction of the bow extension is designed to be particularly large. The calculation of an optimal curvature takes into account the assumed load amplitude, the size of the chain link or the chain pocket, particularly in the bow extension direction, and the deformation behavior of the chain link and the chain pocket, which depends in particular on the material used, which is usually steel. Thus, the curvature in the compression section can essentially correspond to a radius of approximately 1.5 to 10 times, preferably 1.6 to 8 times, the outer width of the chain link.

[0015] The corresponding chain pocket also has a pressure section (hereinafter referred to as the drive section) in the area where a positive connection occurs between the pressure section and the chain pocket. This section is equipped with a complementary, usually concave curvature that is smaller than the curvature of the pressure section. The radius of curvature is thus larger; the drive section on the chain pocket side, which interacts with the pressure section of the chain link, can also be designed as a straight line in the bow extension direction. This enables the chain link to be inserted into the chain pocket.

[0016] By providing a curvature in the compression sections, edge wear is prevented because even if the alignment of the chain link in the chain pocket around the vertical axis of the chain link is not optimal, a large contact surface is always provided which adapts variably with regard to its position along the compression section. Since the respective compression section has a greater extension in the bow extension than the respective contact surface intended during design, the compression section around the intended contact surface provides a type of buffer zone to any edges, in which the contact surface can actually be located in practice without there being any risk of edge wear. The ideal, theoretical contact surface is therefore not limited by edges. The contact surface on the compression section is therefore already structurally adaptive to different positions of the chain link and load intensities.

[0017] Against this background, it is also preferable to keep the radius of curvature in the compression section constant; the compression section is then provided with a uniform radius in the direction of the bow extension. This ensures consistent behavior with regard to the resulting size of the contact surface, regardless of whether the chain link is ideally aligned in the chain pocket or slightly misaligned around its vertical axis, which can be considered a tolerable misalignment.

[0018] In order to provide separate, approximately symmetrically opposed, pressure sections, the intermediate section has, at least in some sections, a greater curvature, and thus a smaller radius of curvature, than the pressure sections. Typically, the radius of curvature of the pressure sections is so large that a continuation of the end face with the same curvature of the pressure sections is not reasonably possible. The corresponding curvature of the intermediate section can also be convex, but also concave. In this case, the intermediate section is set back from the contact surfaces of the pressure sections. Thus, it is also possible to equip chain links with straight front end faces with convex pressure sections and an intermediate section in between in order to achieve the advantages according to the invention.The design of the intermediate section, including its transitions to the compression sections (which are assigned to the intermediate section), thus influences the angle of the compression sections relative to the width direction of the chain link. The intermediate section can have a constant radius of curvature; it is also possible for it to transition into the compression sections at a bent or quasi-bent angle on its sides facing the two compression sections. In this case, it usually has a significantly smaller radius of curvature in the area of ​​the bend than the compression sections. It is also possible for the intermediate section to have the aforementioned, approximately constant curvature only in certain sections, with straight sections extending to the compression sections on both sides. These straight sections are preferably tangents to the two curved sections connected by the straight sections.

[0019] Usually, the pressure sections are symmetrical to each other with respect to the pitch axis of the chain link.

[0020] It is preferably provided that the mean tangent of the curvature in the bow extension direction of each pressure section encloses an angle of 7° to 20°, preferably up to 15°, with the chain link width direction. The mean tangent is the mean value of the tangents of the end face of the possible contact surfaces in the pressure section. The minimum value of this angle is preferably determined by the arctan (µ), where µ is the coefficient of friction of the chain link and the corresponding chain pocket in the contact area. In this way, self-centering of the chain link in the chain pocket is simplified, since the friction-induced self-locking is overcome. However, a larger angle worsens the direction of force introduction into the chain link, which is preferably aligned as parallel as possible to the legs. Against this background, it is preferably provided to further limit the aforementioned angle to 15°, preferably to 12°.

[0021] Furthermore, it can be provided that the pressure section and, usually, also the intermediate section are convexly curved transversely to the bow extension. The front side of the bow is thus curved in the vertical direction; overall, the curvatures in and transverse to the bow extension direction aim to create an elliptical, dome-shaped design of the pressure sections. The radius of curvature transversely to the bow extension can preferably be the same for the pressure section and intermediate section. The aim of this convex curvature is also to create a theoretical point load in the respective contact surface with regard to the chain pocket, which increases in line with the load due to deformation and also to be tolerant of potential misalignment about the transverse axis of the chain link. For this purpose, the radius of curvature of the usually convex chain pocket is larger than that of the chain link and can also be straight.

[0022] Typically, the curvature transverse to the bow extension is significantly greater than in the bow extension and can be approximately half the height of the chain link. The location of the contact surface in the vertical direction, with respect to the curvature transverse to the bow extension, is typically at a position where the tangent of the curvature transverse to the bow extension forms an angle of < arctan (µ) with the vertical direction and thus essentially perpendicular to the tension direction of the chain, where µ is the coefficient of friction of the chain link and the chain pocket in the region of the contact surface. This angle is approximately 7°. Against this background, it is preferably proposed to design the chain pocket such that the contact surface extends at least into the region of the equator line of the chain link.

[0023] Preferably, the bow is designed to be rounded overall. Such a bow can also be described as edgeless. It preferably has convex curves in all directions and no corners or cutting or undercutting pockets. This prevents material from becoming stuck. It goes without saying that the entire chain link is preferably designed to be rounded overall.

[0024] Preferably, the position of the contact surfaces in the width direction of the chain link is limited to the alignment of the legs during normal operation. These are thus aligned with the envelope enclosed by the lateral surface of the respective adjoining legs. This enables particularly advantageous force introduction into the chain link. An offset transverse to the longitudinal extension of the legs between the contact surface and the center fiber of the legs is usually acceptable, although introduction into the center fiber is preferred. By accumulating material in the transition from the bow to the leg, so that the cross-section of the chain link in the transition area is larger than the leg diameter, the force introduced into the legs is evened out.

[0025] It is usually intended to provide the pressure sections of the bow up to the outer width of the chain link.

[0026] In this context, the chain can also be provided with anti-kinking protection. Kinking occurs when the second chain link, engaging with the first link, wraps around a leg of the first link and penetrates the inner width of the first link. This can cause the second link to become incorrectly positioned relative to the first link.

[0027] To prevent this, many different designs are known.

[0028] For example, the legs of the first chain link can be D-shaped in cross-section, providing a stop at the edges of the D. The edges of the D prevent the second chain link from penetrating the first chain link. This is typically achieved by the D-shape, which locally causes the diameter transverse to the insertion direction of the second chain link to be so large that the second chain link cannot be aligned with the first chain link in accordance with the insertion direction. This prevents a tangling situation.

[0029] In another embodiment, self-uncoiling can also be provided as anti-kinking protection. Such a device is described in the application, which has the same seniority as the present application and originates from the same applicant. In particular, a functional section arranged in the bow area is described there. The functional section provides an extension in the bow extension, via which a force can be introduced into the end face of the chain link, as proposed in this application. Reference is made in full to the corresponding embodiments and designs at this point. The first chain link is the horizontal chain link in the nomenclature of the other application.

[0030] The invention is explained in more detail with reference to the accompanying figures. They show: Fig. 1: A three-dimensional view of a first chain link, Fig. 2:a top view of a first chain link in a schematically indicated chain bag as well as complemented by some cuts and Fig. 3: a front view of the bow face with contact surfaces marked at different load levels.

[0031] Figure 1 shows a chain link 1 of a chain (not shown in detail). A second chain link (not shown) engages with the chain link 1 to form a chain. The chain link 1 shown in the figures is a horizontal chain link; the chain link engaging with the chain link 1 is usually referred to as a vertical chain link.

[0032] The chain link 1 comprises two legs 2, 2.1, which are spaced apart from each other and aligned parallel to each other. The two legs 2, 2.1 are symmetrical with respect to the longitudinal axis of the chain link 1.

[0033] The two legs 2, 2.1 are connected to each other by brackets 3, 3.1 in the direction of the bracket extension 4, 4.1. The brackets 3, 3.1 are also symmetrical with respect to the longitudinal axis of the chain link 1 and symmetrical with respect to the transverse axis of the chain link 1.

[0034] In Figure 1 the pitch direction 5 of the chain link 1 as well as its width direction 6 and height direction 7 are also shown.

[0035] The end face 8 of the bow 3 pointing outwards in the division direction 5 (the same applies to the opposite bow 3.1, but due to symmetry it is not further referred to by reference numerals, although all explanations also apply to this bow 3.1) has two pressure sections 9, 9.1 spaced apart from one another in the bow extension direction 4 and an intermediate section 10 connecting the pressure sections 9, 9.1. The intermediate section 10 is directly adjacent to the pressure sections 9, 9.1.

[0036] The pressure sections 9, 9.1 are curved in the bow extension direction 4, with a very large radius, which in this embodiment is approximately 1,500 mm. This corresponds to approximately 9 times the outer width of the chain link 1.

[0037] The intermediate section 10 is also curved with a constant radius in the bow extension direction 4, but has a smaller radius of curvature than the pressure sections 9, 9.1 and is therefore more strongly curved. This is also shown in Figure 2 which shows a top view of chain link 1.

[0038] The front surface 8 of the bow 3, which faces outwards in the direction of division 5, is also curved transversely to the bow extension direction 4, and thus in the height direction 7. However, the curvature here is greater than in the bow extension direction 4 in the pressure sections 9, 9.1, and thus the radius of curvature is smaller. This is also well Figure 2 can be seen in sections AA, BB, and CC, representing the cross-sections of the bow 3 along the indicated sections. The radius of curvature in the vertical direction 7 is constant, with a radius of half the height of chain link 1.

[0039] By the end face 8 of the chain link 1 designed in this way, contact surfaces 13 13.1 are provided in the pressure sections 9, 9.1, via which, starting from a corresponding, in Figure 2 A compressive force is introduced into the bow 3 of the chain link 1 by the schematically illustrated chain pocket 11, so that a tensile force is introduced into the chain (not shown in detail). For this purpose, the chain pocket 11 pushes the chain link 1 in a conveying direction 12.

[0040] Depending on the magnitude of the load between the chain pocket 11 and the chain link 1, the curved pressure sections 9, 9.1 provide a smaller or larger contact surface 13, 13.1. For different load intensities, the contact surfaces 13, 13.1 are cross-hatched in Figure 3, where sub-figure a represents the smallest load level, sub-figure b a medium load level and sub-figure c a high load level. The greater the load, the larger the respective contact area 13, 13.1. This is due to the deformation introduced by the load into the end face 8, or into the pressure sections 9, 9.1. The elliptical-spherical shape of the pressure sections 9, 9.1 is deformed at least in sections by the chain pocket 11, or the drive section 14, 14.1 on the chain pocket side, such that the pressure sections 9, 9.1 rest flat against the drive sections 14, 14.1. It is understood that the drive section 14, 14.1 on the chain pocket side is usually also deformed accordingly, but usually less than the pressure section 9, 9.1 on the chain link side. The curvature of the pressure sections 9, 9.1, particularly in the bow extension direction 4, is so small, or the radius of curvature so large, that even a small load-induced deformation of the pressure section 9, 9.1 results in a relatively large contact surface 13, 13.1, thus reducing the surface pressure. The convex curvature in the bow extension direction 4 of the pressure sections 9, 9.1 also ensures that misalignment of the chain link 1 in the chain pocket 11 about the vertical axis is unproblematic; Although the contact surfaces 13, 13.1 may move on the respective pressure sections 9, 9.1 in the bow extension direction 4, the effect of the deformation-related flattening remains the same, so that the contact surfaces 13, 13.1 do not change in size or do not change significantly under the same load, in particular not if the radius of curvature of the pressure sections 9, 9.1 - as here - is constant.

[0041] The contact surfaces 13, 13.1 are aligned with the legs 2, 2.1. For this purpose, the bow 3, or rather the pressure sections 9, 9.1, are designed to be correspondingly wide, namely, in this embodiment, extending beyond the outer width of the legs 2, 2.1. The chain pocket 11 is also designed accordingly. This achieves a large-area force introduction into the end face 8 of the bow 3. At the same time, the pressure sections 9, 9.1 in this area are relatively flat compared to the width direction 6 of the chain link 1, extending beyond the width of the legs 2, 2.1.

[0042] For self-centering of the chain link 1 in the chain pocket 11, the pressure sections 9, 9.1 are arranged relative to the width direction 6 of the chain link 1. In this exemplary embodiment, the mean tangent 15, 15.1 of the pressure sections 9, 9.1 and the width direction 6 form an angle 16, 16.1 of approximately 8°. This angle 16, 16.1 is greater than the arctan (µ), where µ is the coefficient of friction in the area of ​​the pressure sections 9, 9.1 of the chain link 1 and the drive sections 14, 14.1 of the chain pocket 11. By arranging the pressure sections 9, 9.1 at a larger angle 16, 16.1 relative to the width direction 6 than the angle just mentioned, the friction-induced self-locking is overcome.

[0043] At the same time, the angle of attack 16, 16.1 is kept as flat as possible in order to enable the force to be introduced as straight as possible from the chain pocket 11 into the legs 2, 2.1, thus in the pulling direction of the chain.

[0044] In order to adjust the two pressure sections 9, 9.1 accordingly and still provide a large radius of curvature in the pressure sections 9, 9.1, the intermediate section 10 has a smaller radius of curvature than that in the pressure sections 9, 9.1. The intermediate section 10 extends here as a segment over the angular section by which the pressure sections 9, 9.1 are essentially adjusted (due to the curvature in the pressure sections 9, 9.1, slightly less than the angle pointing in the division direction 5 between the central tangents 15, 15.1 of the pressure sections 9, 9.1).

[0045] The invention has been described using an exemplary embodiment. Without departing from the scope of protection defined by the claims, numerous further embodiments will become apparent to those skilled in the art to implement the inventive concept without the need for further explanation within the scope of these statements. List of reference symbols

[0046] 1Chain link 2, 2.1Leg 3, 3.1Bow 4, 4.1Bow extension direction 5Chain link pitch direction 6Chain link width direction 7Chain link height direction 8End face 9, 9.1Pressure section 10Intermediate section 11Chain pocket 12Conveying direction 13, 13.1Contact surface 14, 14.1Drive section 15, 15.1Mean tangent 16, 16.1Angle between width direction and mean tangent

Claims

1. A chain, in particular for a conveyor with a first chain link (1) designed in particular as a horizontal chain link, the chain link (1) having two legs (2, 2.1) and two ends (3, 3.1) connecting the legs (2, 2.1) by their respective extension (4), wherein the end face (8) of at least one end (3, 3.1) facing outwards in the direction of pitch (5) comprises two pressure sections (9, 9.1) spaced apart from one another in the end extension (4, 4.1) and an intermediate section (10) lying there between connecting the pressure sections (9, 9.1), wherein the pressure sections (9, 9.1) each provide a contact surface (13, 13.1) between the chain link (1) and a corresponding chain pocket (11) of a chain wheel for introducing a tensile force into the chain, characterized in that the end face (8) of the end (3, 3.1) is convexly curved in the direction of the end extension (4, 4.1) in its pressure sections (9, 9.1) and in its intermediate section (10) has at least in sections a smaller radius of curvature than in the pressure sections (9, 9.1).

2. The chain according to claim 1, characterized in that the mean tangent (15, 15.1) of the curvature in the end extension (4, 4.1) of each pressure section (9, 9.1) encloses an angle (16, 16.1) of 7° to 20° with the chain link width direction (6).

3. The chain according to any one of claims 1 or 2, characterized in that the radius of curvature in the end extension (4, 4.1) in the pressure sections (9, 9.1) is constant.

4. The chain according to any one of claims 1 to 3, characterized in that the radius of curvature in the end extension (4, 4.1) is constant in the intermediate section (10).

5. The chain according to any one of claims 1 to 4, characterized in that the pressure section (9, 9.1) is also convexly curved transversely to the end extension (4, 4.1).

6. The chain according to claim 5, characterized in that the curvature of the pressure section (9, 9.1) transversely to the end extension (4, 4.1) is constant.

7. The chain according to any one of claims 1 to 6, characterized in that the end (3, 3.1) is designed to be rounded overall.

8. The chain according to any one of claims 1 to 7, characterized in that the pressure sections (9, 9.1) are provided at least up to the outer width of the legs (2, 2.1).

9. The chain according to any one of claims 1 to 8, characterized in that the chain link and / or the engaging chain link are designed in such a way that interlocking of the two chain links is prevented.

10. The chain according to claim 9, characterized in that the legs of the first chain link are D-shaped in cross section, so that a stop is provided at the edges of the D, preventing a second chain link engaging in the first chain link from being able to dip into the first chain link when it engages around a leg of the chain link.

11. An assembly of a chain according to any one of claims 1 to 10 with a chain wheel, the chain wheel having at least one chain pocket (11) corresponding to the first chain link (1) of the chain.

12. The assembly according to claim 11, characterized in that the chain pocket (11) in the region of the pressure sections (9, 9.1) of the chain link (1) has a larger radius of curvature in the chain link width direction (6) than the pressure sections (9, 9.1) of the chain link (1).

13. The assembly according to any one of claims 11 or 12, characterized in that the contact surfaces (13, 13.1) of the chain link (1) are limited in normal operation to the alignment of the respective adjoining leg (2, 2.1).