CONVEYOR PULLEY, PROCESS FOR PRODUCING A ROLLER TUBE AND DEFORMING TOOL

Abstract

According to the present invention, a conveyor pulley for use in a belt conveyor is provided, comprising: a roller tube (1); wherein the roller tube (1) is formed by plastically deforming a central portion of a substantially cylindrical metal tube (2) radially outwardly so as to form a crowned portion (4) having an enlarged outer diameter (OD.sub.ENL) with respect to remaining portions (6) of the metal tube (2).

Claims

1. A conveyor pulley for use in a belt conveyor, comprising: a roller tube (1); wherein the roller tube (1) is formed by plastically deforming a central portion of a substantially cylindrical metal tube (2) radially out so as to form a crowned portion (4) having an enlarged outer diameter (OD.sub.ENL) with respect to remaining portions (6) of the metal tube (2).

2. The conveyor pulley of claim 1, wherein the material thickness (t) of the metal tube (2) at the crowned portion (4) is substantially equal to the material thickness (t) of the metal tube (2) at the remaining portions (6).

3. The conveyor pulley of claim 2, wherein the outer diameter (OD.sub.ENL) of the crowned portion (4) is about 0.5% to about 3% larger than the outer diameter (OD.sub.ORIG) of the remaining portions (6) of the metal tube (2).

4. The conveyor pulley of claim 1, wherein the crowned portion (4) is substantially cylindrical and wherein a tapered portion (10) or stepped portion is formed between the crowned portion (4) and the remaining portions (6) of the metal tube (2).

5. The conveyor pulley of claim 1, further comprising mounting structures for mounting the conveyor pulley to a frame of the belt conveyor.

6. A process for producing a roller tube (1) of a conveyor pulley for use in a belt conveyor, comprising the steps of: providing a substantially cylindrical metal tube (2); inserting a deforming tool (12) into the metal tube (2), the deforming tool (12) having a radially outwardly expandable deforming portion (18); radially outwardly expanding the deforming portion (18) such that a central portion of the metal tube (2) is plastically deformed radially out so as to form a crowned portion (4) having an enlarged outer diameter (OD.sub.ENL) with respect to remaining portions (6) of the metal tube.

7. The process of claim 6, wherein expanding the deforming portion (18) comprises radially outwardly displacing three rolls (24) having rotational axes substantially parallel to the longitudinal axis of the metal tube (2), and rotating the three rolls (24) about the longitudinal axis of the metal tube (2).

8. The process of claim 6, wherein expanding the deforming portion (18) comprises axially compressing a rubber block (36) such that an outer diameter of the rubber block (36) is expanded.

9. The process of claim 6, wherein expanding the deforming portion (18) comprises radially outwardly expanding an expanding mandrel (40) by displacing a tapered expanding bolt (42) within the expanding mandrel (40).

10. The process of claim 6, wherein expanding the deforming portion (18) comprises axially compressing an expanding fluid (48).

11. A deforming tool (12) for forming a crowned portion (4) of a roller tube (1) of a conveyor pulley for use in a belt conveyor, comprising: an actuator (14); a shaft (16); and a radially outwardly expandable deforming portion (18) arranged at an end of the shaft (16); wherein the deforming tool (12) is configured to be inserted into a substantially cylindrical metal tube (2) and plastically deforming a central portion of the metal tube (2) radially outwardly by radially outwardly expanding the deforming portion (18).

12. The deforming tool (12) of claim 11, wherein the deforming portion (18) comprises three arms (20) hingedly connected to the shaft (16) and axially extending forward from a front axial end of the shaft (16) in an initial state, wherein each of the arms (20) comprise a roll (24) arranged at front ends thereof, rotational axes of the rolls (24) being substantially parallel to a longitudinal axis of the shaft (16) in the initial state, wherein the actuator (14) is configured to displace the front ends of the arms (20) radially out from the initial state.

13. The deforming tool (12) of claim 12, further comprising an actuating rod (26) arranged in an axial bore extending through the shaft (16), wherein a front end portion (30) of the actuating rod (26) is tapered such that the diameter thereof decreases toward a front end of the actuating rod (26), wherein each arm (20) comprises a displacing roll (32) rotatably mounted to the respective arm (20), wherein a rotational axis of each displacing roll (32) is perpendicular to a swinging plane of the respective arm (20), wherein the actuator (14) is configured to push the actuating rod (26) forward so that running surfaces of the displacing rolls (32) come into contact with a surface of the tapered front end portion (30) of the actuating rod (26), such that the tapered front end portion (30) transmits force via the displacing rolls (32) to the arms (20) to displace the arms (20) radially outwardly.

14. The deforming tool (12) of claim 12, further comprising a moving device capable of moving the deforming portion (18) along the longitudinal axis of the shaft (16) and rotating the deforming portion (18) about the longitudinal axis of the shaft (16) or rotating the metal tube (2) about the longitudinal axis of the shaft portion (16).

15. The deforming tool (12) of claim 11, wherein the deforming portion (18) comprises a rubber block (36) whose outer diameter is expandable by axially compressing the rubber block (36), the deforming portion (18) further comprising two pressing plates (34) arranged at both axial ends of the rubber block (36), and wherein the actuator (14) is configured to axially compress the rubber block (36) by displacing the two pressing plates (34) toward each other.

16. The deforming tool (12) of claim 11, wherein the deforming portion (18) comprises a slotted expanding mandrel (40) whose outer diameter is expandable by displacing a tapered expanding bolt (42) within the expanding mandrel (40), and wherein the actuator (14) is configured to displace the tapered expanding bolt (42) within the expanding mandrel (40).

17. The deforming tool (12) of claim 11, wherein the deforming portion (18) comprises two sealing plates (44) capable of defining a fluid-tight space (46) within the metal tube (2), the space (46) being filled with an expanding fluid (48), wherein the actuator portion (14) is configured to displace the two sealing plates (44) toward each other so as to radially outwardly displace the expanding fluid (48).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG. 1 shows a perspective view of a roller tube according to an embodiment.

[0045] FIG. 2 shows a cross-sectional view of the roller tube of FIG. 1.

[0046] FIG. 3 shows a perspective view of a deforming tool according to a first embodiment.

[0047] FIG. 4 shows a cross-sectional view of the deforming tool of FIG. 3.

[0048] FIG. 5 shows a cross-sectional view of the deforming tool of FIG. 3 during use.

[0049] FIGS. 6(a) and 6(b) show cross-sectional views of a deforming tool according to a second embodiment during use.

[0050] FIGS. 7(a) and 7(b) show cross-sectional views of a deforming tool according to a third embodiment during use.

[0051] FIGS. 8(a) and 8(b) shows cross-sectional view of a deforming tool according to a fourth embodiment during use.

DETAILED DESCRIPTION

[0052] FIG. 1 shows a perspective view of a roller tube 1 according to an embodiment, and FIG. 2 shows a cross-sectional view of the roller tube 1 of FIG. 1. Further components, such as bearings, brakes and/or drive mechanisms (not shown) may be mounted in the roller tube 1 to form a conveyor pulley according to an embodiment. The conveyor pulley may further comprise mounting structures (not shown) for mounting the conveyor pulley to a frame of the belt conveyor.

[0053] The roller tube 1 is formed of a metal tube 2 that is substantially cylindrical prior to the forming of the crowned portion 4 by plastic deformation. The remaining portions 6 of the roller tube 1 that are not plastically deformed remain substantially cylindrical and maintain the original outer diameter of the metal tube 2. The crowned portion 4 is arranged in a central portion of the metal tube 2 in the axial direction and comprises a substantially cylindrical or flat portion 8 and tapered portions 10 forming the transitions between the cylindrical portion 8 and the remaining portions 6 at both axial ends of the cylindrical portion 8. The crowned portion 4, particularly the cylindrical portion 8 thereof, has an enlarged outer diameter OD.sub.ENL as compared to the outer diameter OD.sub.ORIG of the remaining portions 6, wherein OD.sub.ORIG is also the original outer diameter of the original metal tube 2 prior to the forming of the crowned portion 4. For example, the remaining portions 6 can have an outer diameter OD.sub.ORIG of about 80 mm, whereas the crowned portion 4 can have an outer diameter OD.sub.ENL of about 81.5 mm. According to a different example, the remaining portions 6 can have an outer diameter OD.sub.ORIG of about 113 mm, whereas the crowned portion 4 can have an outer diameter OD.sub.ENL of about 114.5 mm.

[0054] It is noted that the material thickness t of the steel material of the metal tube 2 is substantially constant along the axial length of the roller tube 1. Therefore, the crowned portion 4, particularly the cylindrical portion 8 thereof, also has an enlarged inner diameter as compared to the inner diameter of the remaining portions 6, which is also the original inner diameter of the original metal tube 2 prior to the forming of the crowned portion 4.

[0055] FIG. 3 shows a perspective view of a deforming tool 12 according to a first embodiment, and FIG. 4 shows a cross-sectional view of the deforming tool 12 of FIG. 3, wherein the cut is made along the central longitudinal axis of the deforming tool 12. The deforming tool 12 according to the first embodiment comprises an actuator 14, a shaft 16 and a radially outwardly expandable deforming portion 18 arranged at an end of the shaft 16. The deforming portion 18 comprises three arms 20 hingedly connected to the front end of the shaft 16 and evenly spaced along the circumference of the end of the shaft 16. The front end or distal end of the deforming tool 12 refers to the end of the deforming tool 12 with which the deforming tool 12 is inserted into the metal tube. The hinged connections allow the distal ends of the arms 20 to hingedly displace radially out. FIGS. 3 and 4 show the deforming tool 12 in the initial state, where the arms 20 are not displaced radially out. In the initial state, the arms 20 are fit snugly in slots 22 (not shown in FIG. 3) formed at the end of the shaft 16 so that the distal front end portions of the arms 20 protrude from the front end of the shaft 16. The arms 20 are connected hingedly to the shaft at the back ends of the arms 20. At each of the front faces of the arms 20, a roll 24 is mounted rotatably. The rotational axis of each roll 24 coincides with or is parallel to the longitudinal axis of the respective arm 20. The rotational axis of each roll 24 is also parallel to the longitudinal axis of the deforming tool 12 or the shaft 16 thereof in the initial state. The rolls 24 are the parts of the deforming tool 12 that come into contact with the metal tube to plastically deform the metal tube.

[0056] As shown in FIG. 4, the deforming tool 12 comprises an actuating rod 26 connected to a piston rod (not shown) of the actuator 14. The actuating rod 26 is arranged in an axial bore extending through the center of the shaft 16. In other words, the actuating rod 26 extends through the shaft 16. A front end portion 30 of the actuating rod 26 is tapered such that the diameter thereof decreases towards the front end. In the initial state, i.e. when the piston rod and the actuating rod 26 are not pushed forward but are retracted, the front end portion 30 of the actuating rod 26 does not protrude or only partly protrudes from the front end of the shaft 16. In order to displace the arms 20 radially out, the piston rod is pushed hydraulically forward to push the actuating rod 26 forward while the actuating rod 26 is being guided by the axial bore of the shaft 16. Each arm 20 comprises a displacing roll 32 rotatably mounted to the respective arm 20. The rotational axis of each displacing roll 32 is perpendicular to the longitudinal axis of the respective arm 20 and also perpendicular to the swinging direction or plane of the respective arm 20. In other words, the rotational axis of each displacing roll 32 is parallel to the rotational axis of the hingedly arranged arm 20, respectively. The displacing rolls 32 are arranged such that the running surfaces of the displacing rolls 32 come into contact with the surface of the tapered front end portion 30 of the actuating rod 26 when the actuating rod 26 is pushed and displaced forward to gradually protrude forward from the front end of the shaft 16. When displaced forward, the tapered front end portion 30 transmits force via the displacing rolls 32 to the arms 20 and gradually pushes the arms 20 radially outwardly.

[0057] FIG. 5 is a cross-sectional view of the deforming tool 12 of FIG. 3. The deforming tool 12 is inserted into the metal tube 2 with its front end to form the crowned portion 4 in the central portion of the metal tube 2. In the state shown in FIG. 5, the crowned portion 4 has already been formed by the rolls 24 of the arms 20. When the three arms 20 are spread apart by the actuating rod 26, each roll 24 of the respective arms 20 comes into contact with the inner wall of the metal tube 2 and plastically deforms the metal tube 2 radially outward. Good centering of the deforming tool 12 and/or the metal tube 2 is provided due to the three-point contact. In order to form the crowned portion 4, the deforming tool 12 and/or the metal tube 2 is rotated about the longitudinal axis of the deforming tool 12 and the deforming tool 12 and/or the metal tube 2 is moved along the longitudinal axis of the deforming tool 12 or metal tube 2 by means of a moving device (not shown).

[0058] FIGS. 6(a) and 6(b) show cross-sectional views of a deforming tool 12 according to a second embodiment, once in a state before forming the crowned portion 4 (FIG. 6(a)) and once in a state after forming the crowned portion 4 (FIG. 6(b)). The deforming tool 12 comprises two shafts 16 each having a pressing plate 34 arranged at the front end thereof. The pressing plates 34 sandwich a rubber block 36 having a cylindrical outer contour corresponding to the inner contour of the metal tube 2 before the forming of the crowned portion 4. The pressing plates 34 and the rubber block 36 form the deforming portion of the deforming tool 12. The shafts 16 and the pressing plates 34 can be displaced toward each other by means of a single actuator (not shown) or actuators provided for each shaft 16, respectively.

[0059] By displacing the pressing plates 34 toward each other, the rubber block 36 is compressed in the axial direction and thereby expands in the radial direction, so that the outer circumferential surface of the rubber block 36 presses against the inner surface of the metal tube 2 and deforms the metal tube 2 from the inside radially outwardly. Thereby, the crowned portion 4 is formed. The axial length of the rubber block 36 before compression substantially corresponds to the axial length of the crowned portion 4 to be formed. The deforming tool 12 comprises an outer forming tool 38 into which the metal tube 2 is placed or inserted prior to the forming of the crowned portion 4. The inner contour of the outer forming tool 38 substantially corresponds to the desired outer contour of the roller tube 1 having the crowned portion 4. That is, the central portion of the outer forming tool 38 has a cylindrically formed inner surface having an enlarged inner diameter as compared to the cylindrically formed inner surface of the remaining portions of the outer forming tool 38. The enlarged inner diameter of the central portion of the outer forming tool 38 substantially corresponds to the enlarged outer diameter OD.sub.ENL of the crowned portion 4 of the roller tube 1. Due to the outer forming tool 38, the metal tube 2 is allowed to be deformed radially out at the center portion of the metal tube 2 and the outer forming tool 38, whereas the metal tube 2 is prevented from being deformed at the remaining portions of the metal tube 2 and the outer forming tool 38. Thus, the outer contour of the finished roller tube 1 can be controlled precisely in a simple manner.

[0060] FIGS. 7(a) and 7(b) show cross-sectional views of a deforming tool 12 according to a third embodiment, once in a state before forming the crowned portion 4 (FIG. 7(a)) and once in a state after forming the crowned portion 4 (FIG. 7(b)). The deforming tool 12 according to the third embodiment is a modification of the deforming tool 12 according to the second embodiment. Explanations about identical parts, such as the metal tube 2, the actuator, the shafts 16 and the outer forming tool 38 are, therefore, omitted. The deforming tool 12 of the third embodiment comprises a slotted expanding mandrel 40 and two tapered expanding bolts 42 as the deforming portion. The tapered expanding bolts 42 are formed or arranged at the front ends of the shafts 16. When the shafts 16 and the expanding bolts 42 are displaced toward each other by the actuator, the outer surface of the expanding bolts 42 come into contact with a tapered inner surface of the expanding mandrel 40 to expand the expanding mandrel 40 radially outwardly so as to form the crowned portion 4. The axial length of the expanding mandrel 40 substantially corresponds to the axial length of the crowned portion 4 to be formed.

[0061] FIGS. 8(a) and 8(b) show cross-sectional views of a deforming tool 12 according to a fourth embodiment, once in a state before forming the crowned portion 4 (FIG. 8(a)) and once in a state after forming the crowned portion 4 (FIG. 8(b)). The deforming tool 12 according to the fourth embodiment is also a modification of the deforming tool 12 according to the second embodiment. Explanations about identical parts, such as the metal tube 2, the actuator, the shafts 16 and the outer forming tool 38 are, therefore, omitted. The deforming tool 12 of the fourth embodiment comprises two sealing plates 44 defining a fluid-tight space 46 within the metal tube 2, and the space 46 is filled with an expanding fluid 48 such as water or oil, as the deforming portion. The sealing plates 44 are formed or arranged at the front ends of the shafts 16. A fluid-channel 50 extends through the shafts 16 and the sealing plates 44, so that the fluid-tight space 46 can be filled with the expanding fluid 48 through the fluid-channel 50. When the shafts 16 and the sealing plates 44 are displaced toward each other by the actuator, pressure is built up in the expanding fluid 48 so that the expanding fluid 48 expands radially out at the center portion of the metal tube 2 where a radially outward deformation of the metal tube 2 is permitted by the outer forming tool 38, so as to form the crowned portion 4. A splitted outer forming tool 38 comprising two or more parts can be provided for easy withdrawal of the metal tube 2 with the crowned portion 4.

LIST OF REFERENCE SIGNS

[0062] 1 roller tube [0063] 2 metal tube [0064] 4 crowned portion [0065] 6 remaining portion [0066] 8 cylindrical portion [0067] 10 tapered portion [0068] 12 deforming tool [0069] 14 actuator [0070] 16 shaft [0071] 18 deforming portion [0072] 20 arm [0073] 22 slot [0074] 24 roll [0075] 26 actuating rod [0076] 30 front end [0077] 32 displacing roll [0078] 34 pressing plate [0079] 36 rubber block [0080] 38 outer forming tool [0081] 40 expanding mandrel [0082] 42 expanding bolt [0083] 44 sealing plate [0084] 46 fluid-tight space [0085] 48 expanding fluid [0086] 50 fluid-channel [0087] OD.sub.ENL enlarged outer diameter [0088] OD.sub.ORIG original outer diameter