MXPA98006197A - Tensioning device for a belt scraper - Google Patents

Abstract

A tensioning device (20) for adjusting the contacting/cleaning force of a scraper blade (16) on the surface of an endless conveyor belt (19) is provided for use on a shaft (18) supporting the scraper blade (16). The tensioning device (20) allows the shaft (18) to be rotated and locked in a position which is very close to its optimum cleaning position, thereby increasing the efficiency of the scraper assembly (10). The disclosed tensioning device has three collars (22, 24, and 28) with a spring (26) located in between the rotatable collar (28) and adjusting collar (24). Sequences of axially-directed apertures on the adjusting collar (24) and the stationary collar (22) move into and out of registry with each other as the adjusting collar (24) is rotated. A locking pin (58) is through the aligned holes in adjusting collar (24) and stationary collar (22) when the desired amount of torsion is applied to the shaft (18).

Description

TENSION DEVICE FOR A BAND SCRAPER FIELD OF THE INVENTION The present invention relates to a tensioning device for adjusting the force with which the blade of a conveyor belt scraper makes contact with the surface of the conveyor belt.

BACKGROUND OF THE INVENTION U.S. Patent No. 5,201,402 assigned to ASGCO Manufacturing, Inc., assignee of the present application, discloses a tension device for adjusting the contact force of a scraper blade on an endless conveyor belt. The tensioning device described herein is a rotary tensioner that adjusts the contact force of the scraper blade on the surface of the conveyor belt by controlling the torque or torque exerted on a rotating shaft supporting the scraper blade. To that end, a tension collar and an adjustment collar are disposed or located adjacent to each other on the support shaft. The adjustment collar is fixed to the support shaft and rotates with it. The tension collar is connected to one end of a torsion thrust mechanism such as a coil spring. The other end of the mechanism P1473 / 98MX thrust is fixed to the conveyor belt frame. Each collar has a series of holes formed therethrough, the holes are arranged at a selected radial distance from the axis of the support shaft. As the collars rotate with respect to each other, the torsional thrust on the supporting shaft increases or decreases and the holes in one collet move towards an axial housing and out of it with the holes in the other collet. Each series of holes has different spacing between the respective holes, so that the torsion thrust can be adjusted in very small increments. The collars are secured in the relative position by inserting a safety bolt through two aligned holes. Although the known device works well, in practice it was found that the adjustment of the torsion thrust of the tensioning device requires the effort of two people. In the arrangement described in the aforementioned patent, a hand is needed to rotate the tension collar and a second hand is necessary to hold the scraper blade in engagement with the surface of the conveyor belt, rotating the support shaft . The last operation is usually done by turning the adjustment collar in the opposite direction to that of the tension collar. Then it is P1473 / 98MX requires a third hand to insert the safety pin through the aligned holes in the collars, because the first two hands must be used to keep the two collars in proper alignment.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a tensioning device for adjusting the contact force of a scraper blade on an endless conveyor belt. The tensioning device adjusts the contact force of the scraper blade on the surface of the conveyor belt by controlling the torque or torque exerted on the rotating shaft by the torsion thrust mechanism. The tensioning device is designed to be operated by a single person with very little difficulty. The tensioning device has a supporting arrow with an axis parallel to the conveyor belt. The tensioning device comprises three collars and a torsion thrust mechanism located on the support shaft. A rotating collar is fixed to the free end of the arrow. An adjustment collar is rotatable about the axis of the arrow and has a sequence of circumferentially spaced openings around the adjustment collar.

P1473 / 98MX equal increments. A torsion thrust mechanism, arranged or located between the rotary collar and the stationary collar, is connected at one end to the adjusting collar and connected at the other end to the rotary collar. A stationary collar, located adjacent to the adjustment collar, is fixed to the conveyor frame and has a sequence of circumferentially spaced openings around the stationary collar at equal increments. As the adjustment collar rotates, the holes in the adjustment collar and the stationary collar move to register and out of register with each other. The tensioning device is secured or locked by inserting a safety bolt into a pair of holes in the register. The thrust placed on the torsion thrust mechanism by the rotation of the adjustment collar causes the arrow to rotate and maintain a tension in the scraper blade against the band. A single person can both rotate the adjustment collar and insert the safety bolt through the openings in the adjustment collar and the stationary collar.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a conveyor belt scraper unit having a P1473 / 98MX rotating tensor device in accordance with the present invention; Figure 2 is a perspective view of the rotating tensor device shown in Figure 1; Figure 3 is a front elevational view of the rotating tensor device of Figure 2 as seen along the line 3-3 therein; and Figure 4 is a front elevational view in partial section of the rotating tension device of Figure 2, as viewed along line 4-4 therein; and Figures 5a-5f are diagrammatic illustrations of the rotation and alignment of the openings in the stationary collar 22 and in the adjustment collar 24 used in the rotating tensioning device of Figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings and, in particular, to Figure 1, there is shown a conveyor belt scraper unit 10 which is disposed or located adjacent to the head roller 12 of an endless conveyor belt 19 moving in the direction indicated by the arrow "A". The conveyor belt scraper unit includes at least one scraper blade 16 which is mounted on a rotating support shaft 18.

P1473 / 98MX A tensioning device, generally denoted by the reference numeral 20, is located at one end of the supporting arrow 18. The tensioning device 20 is constructed and arranged to exert a torque or torque on the arrow 18 which pushes the scraper blade 16 toward a tight or tight engagement with the surface of the conveyor belt 19. Referring now to Figures 2, 3 and 4, the tension device 20 is shown in greater detail. The tensioning device 20 includes a stationary collar 22, an adjustment collar 24, a helical spring 26 and a rotating collar 28, all of which surround the support shaft 18 and are aligned coaxially with it. The stationary collar 22 is fixed to a mounting bracket 30 by means of a spacer sleeve 31. The mounting bracket 30 is constructed for connection to a fixed support structure such as the frame 14 of the conveyor. A bearing spacer 32 has a ring-shaped portion 33 located between the stationary collar 22 and the adjustment collar 24. The bearing spacer 32 also has a first barrel-shaped portion 34a extending from the shaped portion 33 of a ring through a central bore in the stationary collar 22 and through a central bore in the spacer sleeve 31. A second barrel-shaped portion 34b of the P1473 / 98 X bearing spacer 32 s extends from the ring-shaped portion through a central bore in the adjustment collar 24. The bearing spacer 32 is formed of a synthetic plastic material such as nylon, to provide a protective and low friction bearing surface between the adjusting collar 24 and the stationary collar 22 and between the arrow 18, the spacer sleeve 31 and the adjustment collar 24. The presence of the bearing spacer 32 is particularly effective in corrosive environments to avoid corrosion welding between the stationary collar 22 and the adjustment collar 24. The ring portion 33 also functions to maintain a fixed space between the stationary collar 22 and the adjustment collar 24, which facilitates the visual alignment of the openings in the respective collars. The adjustment collar 24 has a central bore therethrough which is dimensioned in such a way that the adjustment collar 24 is free to rotate around the support arrow 18. A first end 44 of the coil spring 26 is secured in a first opening formed in the adjusting collar 24 and held in place by a set screw 46. The other end 48 of the coil spring 26 is disposed or located in an aperture formed through the rotary collar 28 and holds in its P1473 / 98MX instead by means of a fixing screw 54. The rotary collar 28 is fixed to the supporting shaft 18 by means of fixing screws 52 located at selected positions around the circumference of the rotary collar 28. When the supporting shaft 18 the desired amount of torque has been applied by aligning an opening 56 in the adjustment collar 24 with an opening 62 in the stationary collar 22, a securing bolt 58 is inserted through the aligned openings to prevent relative rotation between the two collars 22 and 24. The arrangement and use of the openings is described more fully below. The adjustment collar 24 also has a plurality of tool engagement holes 60 located radially at selected intervals around the periphery thereof, for receiving a tool or adjustment lever to assist in the rotation of the adjustment collar 24 with the spring of thrust 26 to the appropriate torsional tension. It is contemplated that instead of a coil spring, the torsional thrust device may take the form of a piece of resilient elastomeric material having sufficient elasticity and strength to allow for the controlled torsional deformation that is necessary to adjust the torque. applied to arrow 18. The P1473 / 98MX suitable materials and their relevant properties are known to those skilled in the art. When these materials are used, they are preferably formed in the form of a straight cylinder which is arranged around the supporting arrow 18. One end of the cylinder is connected to the adjusting collar 24 and the other end is connected to the rotary collar 28. Referring now to Figures 5a-5f, the adjustment collar 24 has a preselected number of equally spaced and axially directed apertures 56 located radially on a circle having a radius "r" measured from the axis of rotation of the adjustment collar 24. The openings 56 are arranged circumferentially and spaced apart by a preselected angular distance "a". In a preferred embodiment, the adjustment collar 24 has fifteen openings 56 spaced apart consecutively from each other in a sequence at 22.5 degrees of arc. The separation between the first and the last opening of the sequence is twice the spacing within the sequence, because a different opening is needed near that location to secure the end 44 of the torsion spring 26. Referring back to Figures 2-4, the adjustment collar 24 cooperates with a third stationary collar or collar 22 mounted adjacently to P1473 / 98MX adjust the torque exerted on the arrow 18 by the torsion spring 26. The stationary collar 22 is welded or fixed in some other way to the mounting bracket 30. The stationary collar 22 is preferably of smaller diameter than the adjustment collar 24 but can be of equal or greater diameter compared to the adjustment collar 24 or with the rotary collar 28. The stationary collar 22 preferably has a preselected number of equally spaced and axially directed apertures 62 located radially on a circle having a radius "r" measured from the axis of rotation of the adjustment collar 24 as indicated in Figures 5a-5f. The openings 62 are circumferentially spaced apart by an angular distance "b". In the embodiment shown, the stationary collar 22 has five openings spaced consecutively at 18 degrees from each other. The angular separation between the openings is 80% of the spacing between the openings 56 of the adjustment collar 24. The radius "r" of the arc of the openings 62 in the stationary collar 22 is the same radius as the series of openings 56 in the adjustment collar 24. However, for purposes of clarity in the illustration, the circle of openings 62 is shown in a larger radius in Figures 5a-5f. The openings in the adjustment collar 24 and in the P1473 / 98MX stationary collar 22 preferably have the same diameter size to receive the securing bolt 58 when a pair of holes (one of each of the adjusting collar 24 and the stationary collar 22) are properly aligned. The position of the securing bolt 58 is represented by the shaded openings 58a-58f. Since the circumferential spacing between the openings 62 of the stationary collar and the openings 56 of the adjusting collar is different, only a pair of holes 56, 62 are properly aligned at the same time. As the adjusting collar 24 rotates, a different pair of openings is aligned, thereby changing the magnitude of the torque exerted by the spring 26. The sequential registration of the openings in the stationary collar 22 and in the adjusting collar 24 is illustrated diagrammatically in Figures 5a-5f for a tensioner having an adjustment increment "c" of 4.5 arc degrees. As shown in Figure 5a, two holes 56, 62 are aligned in the position 58a and are capable of receiving a common securing bolt to prevent movement of the adjustment collar 24 and the stationary collar 22 with respect to each other. In the modality, starting from the 12:00 position in the circle defined by the openings 56, the fifth opening P1473 / 98MX 62 is in register with the tenth aperture 56. To adjust or tighten the scraper blade, the securing bolt 58 is removed and the adjustment collar 24 is rotated an angular increment c, ie, 4.5 degrees until the next pair of holes 56, 62 are suitable for receiving the securing bolt as illustrated in 58b of Figure 5b. In this case, the fourth opening 62 is in register with the ninety opening 56. If the tension in the scraper blade is still insufficient, the adjustment collar can be rotated an additional increment until another set of openings is aligned as illustrated in FIG. 58c of Figure 5c. Here, the third opening 62 is in register with the eighth aperture 56. Figures 5a-5f illustrate the registration sequence of the apertures as the adjustment is rotated through additional increments, at which point, the fifth aperture 62 is again in register or is aligned with an opening in the adjustment collar 24 as illustrated at 58f of Figure 5f, in this case, the ninety opening of the sequence 56. The sensitivity of the present tensioning device is not limited by the minimum separation between the openings in any collar. The minimum adjustment increment of the present tensioning device is much smaller than the minimum distance between the openings in either the P1473 / 98MX adjustment collar or stationary collar. This increase in sensitivity allows the scraper blades to be adjusted much closer to their optimal cleaning position and, thus, increase the efficiency of the scraper blade unit. The preferred embodiment of the tensioning device allows the adjustment in increments of 20% of the spacing between the openings 56, ie, 4.5 degrees. In additional embodiments, the tensioner may be designed for adjustment in even smaller increments by changing the number and spacing of the openings in the stationary collar 22. The number of openings in the stationary collar, Y, is calculated by dividing the desired adjustment increment in degrees, c, between the relative spacing of the openings in the adjustment collar in degrees, a, Y = a / c The relative spacing of the openings in the stationary collar in degrees, "b", is calculated by subtracting the increase in desired setting in degrees, "c", of the relative separation in degrees "a". of the openings in the adjustment collar b = a-c For example, a tensioner that has an adjustment increment of 1.5 degrees and that has openings in the collar P1473 / 98MX adjustment equidistantly separated every 22.5 degrees, requires fifteen openings (Y = 22.5 / 1.5) in the stationary collar. The relative separation of the openings in the stationary collar is 21 degrees (b = 22.5 ° -l / 5 °). it should be noted that 15 openings are spaced about 315 degrees from the circle in the stationary collar. Using the aforementioned equations, the specific design parameters of the present tensioning device can be adjusted to admit or accept several applications. In an additional embodiment illustrated in Figures 5a-5f, at least one of the openings in the stationary collar 22 is displaced from the consecutive series of openings as previously illustrated. The location and separation of the respective openings is calculated in the same manner as in the first illustrated embodiment. However, the openings that are displaced from the consecutive sequence must be displaced by the distance or by an integral factor of the distance, between the openings of the adjustment collar. For example, the stationary collar 22 has an adjustment of 4.5 degrees, has a consecutive sequence of openings 62 located at 0 °, 18, 36 °, 54 ° and 72 °. In this additional embodiment, the second and fourth openings 62 are offset a distance (N x a) from their original location, where "N" is an integer that is P1473 / 98MX selects to locate the openings displaced in the desired location and "a", as previously mentioned, is the arc distance between the openings 56 in the adjustment collar 24. Thus, the location of any of the Decentral openings with respect to the first reference opening or opening of the series are determined by the ratio. [(n - 1) X (a - c)] + (N X a), where n is the order of the opening in the sequence before displacement. In each of the aforementioned embodiments, it is preferred that the total arc required for the holes in the adjustment collar be less than 360 °. Thus, Y x b, must be less than 360 ° to avoid overlap of the openings in the adjustment collar. Referring again to Figure 1, the axially directed openings 56, 62 in the adjusting collar 24 and in the stationary collar 22, respectively, are aligned normal to the direction of the falling debris which is scraped from the web 19. to that orientation, the openings resist to the contamination coming from the falling waste which could cover the openings and hinder the insertion of the securing bolt 58. It will be appreciated from the description P1473 / 98MX that when using the previously described tensioner, only one hand is needed to rotate the blade towards the coupling with the band and the tension of the spring, thus leaving the other hand of the operator free to insert the bolt. securement 58 through the aligned adjustment holes or remove it from them. In this way, the tension operation can be performed by a single person with very little difficulty, if any. Those skilled in the art will recognize that changes or modifications can be made to the embodiments described above without deviating from the broad concept of the invention. Therefore, it should be understood that this invention is not limited to the particular embodiments described herein but is intended to include all changes and modifications that are within the scope and spirit of the invention as set forth in the following claims .

P1473 / 98MX

Claims (9)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property:

1. A tension device for adjusting the contact force of a scraper blade on the surface of an endless conveyor belt mounted on a support structure, the tension device comprises: an arrow having an axis parallel to the conveyor belt; a first collar connected or attached to the arrow; a second collar having a hole for receiving the arrow and rotating around the arrow, the second collar having at least one opening at a preselected distance from the axis of the arrow; a torsion thrust mechanism for applying torsion to push the arrow and causing the blade to rest against the conveyor belt, the torsion thrust mechanism is located between the second collar and the first collar and has one end connected to the second collar and the other end connected to the first collar; a third collar connected to the support structure and arranged adjacent to the second collar P1473 / 98MX along the arrow, the third collar has at least one opening at the preselected distance from the axis of the arrow, the third collar also has a central hole to receive the arrow therethrough; and a securing bolt adapted to engage with an opening of the second collar and an opening of the third collar when the openings are in register with each other. The tension device according to claim 1, further comprising a spacer sleeve extending laterally from the support surface and being fixed to the third collar to fix the third collar to the support structure, the spacer sleeve has a borehole central aligned coaxially with the central bore of the third collar. The tension device according to claim 1, wherein the second collar has a sequence of openings that are circumferentially spaced around the second collar at the preselected distance from the axis of the arrow. The tension device according to claim 1, wherein the third collar has a sequence of openings that are circumferentially spaced around the third collar at a distance P1473 / 98 X preselected from the axis of the arrow. The tension device according to claim 1, wherein the torsion thrust mechanism comprises a helical spring. The tension device according to claim 1, wherein the second adjustment collar has at least one opening radially directed on the external surface of the element for receiving a tool for rotating the second adjustment collar about the axis of the arrow. The tension device according to claim 1, further comprising a non-corrosive bearing spacer located between the second collar and the third collar and formed to maintain a fixed space between the second collar and the third collar. The tension device according to claim 7, wherein the bearing spacer is formed of an antifriction material to reduce the friction between the second collar and the third collar. The tension device according to claim 7, wherein the bearing spacer comprises a first barrel-shaped portion disposed between the second collar and the arrow and a second barrel-shaped portion disposed between the third collar and the arrow. P1473 / 98MX