Background of the Invention

The invention relates to conveyor belt systems and in particular to a tool for removing the worn lagging strips on a conveyor belt drum.

A common problem in conveyor belt systems where the belt is used to transport heavy materials, for example coal, is slippage of the conveyor belt on the pulley drums which drive the belt. A recent development has been the use on the drums of what are referred to "lagging strips". Lagging strips are long, rectangular,, rubber strips which are secured to the circumference of the drum parallel to the axis of rotation. They have a thick central rubber portion which contacts the conveyor belt, and a thin border strip which secures the lagging strip to the drum by means of metal strips which are welded to the drum and are provided with clips to secure the edges of the lagging strips. This configuration has been found to give much better friction between the drum and the conveyor belt than would a continuous coating of rubber on the drum. The strips are typically 5 5/8 inches wide and 11/16 inches thick.

As the lagging strips become worn it is necessary to replace them. This has been a difficult task as the metal clips become rusted and the lagging strips fused to the surface of the pulley. In the past, the method of removing the lagging has been to utilize a torch to loosen the lagging, use a hammer and chisel to loosen the metal clips from the lagging strips, and then use a tool such as a "come-along", hammers and chisels and torches to strip and remove the lagging from the,pulley. This is a diffi¬ cult and time consuming procedure. In the past up to four hours have been necessary to remove a single lagging strip, and it is also then difficult to install a new lagging strip as the metal clips have been bent out of shape and

damaged. Further, in order to carry out this procedure it is necessary to shut the machine down, remove the pulley from the machine and transport it to a shop where the various tools are available. This results in the machine being out of commission for an extended period of time, resulting in substantial economic loss, unless the facility maintains replacement drive pulleys. As a typical drive pulley has about twelve lagging strips, it is apparent that the previous method was extremely time consuming.

The present invention provides a tool for quickly and effectively removing lagging strips from drive pulley drums. The present invention also leaves the metal clip in a condition after removal of the lagging strip such that the replacement strip may be easily installed. The present invention may be mounted directly on the pulley drum while the drum is still in place in the machine and accordingly it is not necessary to remove and transport the pulley drum. In contrast to prior methods, the present method allows the lagging strips from an entire drum to be removed much more quickly. Further, the procedure leaves the metal clips in a condition whereby the replacement lagging strip can be easily installed.

Summary of the Invention

The present invention provides an apparatus for removing lagging strips from a conveyor belt pulley drum which comprises:

(a) a tool head having a lower surface having a circumference conforming to the outer circumfer¬ ence of the pulley drum whereby the tool head is adapted to slide in close contact with the outer circumference of the pulley drum, and lower forward edges which are adapted to simultaneously

slide under and raise the metal clips which secure the lagging strips;

(b) guide means adapted to be secured to the drum and to guide the tool head across the surface of the drum; and,

(c) power activated means for moving the tool head across the drum against the lagging strip in order to remove the lagging strip.

The guide means may comprise parallel, tubes between which the tool head is guided. The power activated means may comprise a hydraulic cylinder to push the tool head, or winching means to pull the tool head across the surface of the drum.

The invention further provides a method for removing lagging strips from the surface of the conveyor belt pulley drum comprising the steps of installing guide means for guiding a tool head across the surface of the drum in alignment with the lagging strips, and driving or pulling a tool head against the lagging strip using power- activated means in order to push or pull the lagging strip from under its securing metal strips.

Brief Description of the Drawings

In drawings which illustrate an embodiment of the invention:

Figure 1 is a perspective view showing the lag¬ ging strip removing apparatus pf the invention prior to mounting on the pulley drum;

Figure 2 is a perspective view of the invention mounted on a pulley drum and viewed from one end;

Figure 3 is a partial cross-sectional view along the lines III-III of Figure 2 showing the lagging strips and metal clip strips;

Figure 4 is a partial top view showing the tool guide assembly;

Figure 5 is a top view showing the hydraulic cylinder assembly of the invention;

Figure 6 is a cross-sectional view taken along line VI-VI of Figure 5;

Figure 7 is a cross-sectional view of. the tool head assembly mounted on the pulley drum taken along lines VII-VII of Figure 2;

Figure 8 is a top view of the tool head;

Figure 9 is a side view of the tool head;

Figure 10 is a cross-sectional view taken along lines X-X in Figure 2;

Figure 11 is a cross-sectional view taken along lines XI-XI of Figure 5;

Figure 12 is a cross-sectional view taken along lines XII-XII of Figure 5;

Figures 13a, 13b and 13c are side and end views of a coupling used in the invention;

Figure 14 is a top view of a second embodiment of the invention using a hydraulic winch rather than a hydrau¬ lic cylinder; and.

Figure 15 is a side view of the embodiment shown in Figure 14, partially cut away to reveal the structure.

Detailed Description of an Embodiment of the Invention

With reference to Figures 1 through 3, the lag¬ ging strip removal apparatus of the invention is referred to generally as 1. It is shown in Figures 2 and 3 mounted on pulley drum 3. Drum 3 has secured to its outer circum¬ ference lagging strips 5. Such strips are manufactured specifically for improving traction on the conveyor belt driven by the pulley drum and are of an extremely tough rubber. They are provided with treads to increase the traction. They are secured to the outer surface of the drum by metal clip strips 7. Such clip strips are welded to the surface of the drum, and have flanges 9 which bear against edges 11 of the lagging strips. The size of drum 3 will vary according to the particular conveyor belt system.

The lagging remover 1 has two parallel guides 15 formed of two inch diameter stainless steel tubing. Guides 15 are maintained in parallel relationship by cross-pieces 17 and cylinder guide assembly 18. Also secured to either end of each guide are height guides 19 and 20 which permit the device to be mounted on pulley drums of varying diameters using adjustable screws 21 and 22. Height guides 19 and 20 rotate freely on guides 15 to allow them to form different angles to the vertical and thus adapt to various curvatures of the drum. Cross-piece 17 is notched to allow the lagging strip to pass under it. Cross-piece 17 is mounted on sleeves 16 (see Figure 10) which slide on guides 15. Bolts 29 secure sleeves 16 in position on the guide bars by means of holes in the ends of the bars.

Height guides 20 are similarly free to rotate on guides 15 to permit mounting on drums of various diameters. They are provided with adjustment screws 22 to allow secur¬ ing to the edge of the drum. The inner portion of the height guides 19 and 20 are half-sleeves to permit the tool head assembly to pass over top of them.

Mounted on cylinder guide assembly 18 is hydrau¬ lic cylinder 23. Hydraulic cylinder 23 has cylinder rod 24 which extends or retracts in response to the entrance or removal of pressurized hydraulic fluid into the hydraulic cylinder. The cylinder is mounted on cylinder mount 25, shown in further detail in Figure 6. The height of cylin¬ der mount 25 with respect to the guide bars can be adjusted by adjustable bolt 26. Guide assembly 18 consists of cross-piece 27 through which passes bolt 26, vertical extensions 28 which are secured to cross-piece 27, and slotted blocks 33 in which the cylinder mount slides. The blocks 33 are in turn secured to sleeves 11 which slide on guide bars 15 and are secured by bolts 29 which pass through holes in the end of the bars. Guide bar 55 is secured to the lower cross-piece of mount 25.

Mounted for longitudinal movement on guides 15 is tool head assembly 30 shown in Figure 4. It consists of two pipe sections 32 having an interior diameter slightly greater than the diameter of guides 15 and provided with a sleeve bearing to allow easy movement along the guides. Cross-piece 34 is welded to the two pipes 32. In turn bolted to cross-piece 34 by bolt 35 is the tool 36 (see Figures 7-9) . Tool 36 has a curved lower edge 37 to match the outer circumference of the pulley drum. The tool 36 also has outside edges 38 which, are tapered or pointed to slide under the edges 9 of metal clips 7.

Bolted to tool 36 by bolt 39 is a push bar 40, and bolted in turn to push bar 40 is a saddle 42 which

receives the push rod. A clevis pin 44 is provided to hold the push rod in place.

A coupling unit 50 shown in Figures 13a, 13b and 13c is utilized to connect the end of the cylinder rod 24 to the various extension rods as described further below. The coupling nut has a socket 52 which receives the end of the cylinder rod, and a U-shaped receptacle 54 on the other end of the unit which receives the end of the extension rod. A clevis pin 56 can be inserted to retain the exten¬ sion rod 58 in place.

Guide bars 15 of different lengths are required for drums of different widths. Prior to installing the device the guide bars of appropriate length are selected and the tool head having the appropriate curvature to match the pulley drum is selected and installed on the tool head assembly 30. To mount the apparatus on the pulley drum, the guide bars 15 are laid loosely in parallel position on either side of the lagging strip to be removed. The tool head assembly 30 is mounted on the guide bars at an inter¬ mediate position. The height guide assemblies 19 and 20 may then be slipped in either end of the guide bars and tightened against the drum. Cross-pieces 17 and cylinder guide assembly 18 are then installed and bolted to the ends of the guide bars.

The height of the tool head is then adjusted to the appropriate level by adjustment bolt 35 so that the tool will just scrape along the surface of the drum and the tool edges 38 will slide under the edges 9 of the metal clips and lift them slightly as the tool is pushed down the length of the lagging. The cur ed edge of the tool head will contact the base of the lagging just above where it contacts the surface of the pulley drum. The height of the cylinder mount is adjusted by sliding in blocks 33 so that the top of the guide bar 55 is aligned with the surface of

the drum and the cylinder rod will contact the tool head assembly in the appropriate location. This is done by ad¬ justing the two nuts 57 on bolt 26. Adjustment screw 56 may then be tightened against the drum.

The hydraulic cylinder may then be activated to drive the end of the cylinder rod and tool head assembly against the end of lagging strip 5. On the order of 5,000 pounds of pressure will be required to initiate the move- ment. Once the cylinder rod has been fully extended, which is approximately 13 1/8 inches in a standard case, the cylinder rod is retracted, coupling nut 50 is inserted over the end of cylinder rod 24, and an extension rod approxi¬ mately 12 3/4 inches in length is inserted into the other end 54 of the coupling nut. The cylinder is again extended to contact the head assembly and drive the end of the extension rod against the tool head assembly through the full stroke of the hydraulic cylinder. This process is repeated, replacing the extension rod with extension rods of 25 1/5 inches, 38 1/4 inches and 51 inches in length until the tool nut assembly has been driven across the entire 66-inch width of the drum.

It will be seen that the tool head assembly in this way not only drives the lagging from the surface of the drum, but slides under and raises the metal clips which are then ready to receive the new lagging. This is facili¬ tated by the rounded forward edge of the tool head edges 38 as shown in top view in Figure 8. Also as previously indicated, the curvature of the lower surface of the tool head will vary according to the outside diameter of the pulley drum, and the length of guide bars 15 will be se¬ lected according to the width of the drums. The tool head r will preferably be formed of hardened tool steel.

As shown in Figures 14 and 15, rather than util¬ izing a hydraulic cylinder to drive the tool head, a

hydraulic winch 60 having a free-spooling clutch may be connected to the tool head assembly by a cable 62 to pull the tool assembly rather than using a hydraulic cylinder to push it. In other respects, this embodiment operates identically to the embodiment using the hydraulic cylinder.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope there¬ of. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.