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Excel Expertise: Eliminate Excessive Bowl Movement in Your HP700™ Cone Crusher

Excel’s resident Expert, Service Manager Ken Olson, recently visited a concentrator plant in South America where he witnessed the bowl assembly of an HP700™cone crusher dancing (moving about) in the adjustment ring assembly during normal crushing operations. A check of the hydraulic power unit showed that the clamping circuit was at the proper pressure, though it was showing cyclic fluctuations. Ken concluded that this was a classic example of the bowl clamping system not functioning properly due to excessively worn bowl and adjustment ring buttress threads. The following is Ken’s synopsis of the situation and how to avoid it in your operation.

Over time, the threads of the bowl and adjustment Ring of this type of crusher wear, with the wear typically most pronounced in the bottom two thread turns of the bowl and the top two thread turns of the adjustment ring. This progressive wear requires more vertical travel of the clamp ring to lock the bowl in the adjustment ring, particularly with a new set of liners. Eventually, the clamp ring is physically limited in vertical travel by the capscrews that retain it to the adjustment ring. When this happens, it is no longer possible to jam the bowl threads to the adjustment ring threads on the 45 degree surfaces and lock the bowl assembly tight to the adjustment ring assembly.

The vertical travel of the clamp ring is also limited by the stroke of the clamping cylinder. The physical limit of vertical travel for the clamp ring is defined by a washer and capscrew that are drawing up tight to a tube spacer that projects above the clamp ring.

EBlast Tube Spacers Call Out2 Excel Expertise: Eliminate Excessive Bowl Movement in Your HP700™ Cone Crusher

What’s more, the initiation of the bowl movement during crushing will accelerate thread wear; that is, the problem will rapidly become worse. This can also lead to sections of thread breaking out of the bowl and the adjustment ring, particularly at the thread starts. This problem is most pronounced after a liner change, when the actual thread engagement between the bowl and the adjustment ring are at a minimum. Bowl movement is usually associated with bowl creep as the crushing forces overcome the clamping forces, another serious issue for these crushers.

Standard maintenance practice dictates that it will be necessary to rebuild the bowl threads and/or the adjustment ring threads. However, there is an interim step that can buy additional service time. Shim spacers of equal thickness, something in the range of 4 to 4.5 mm, or 3/16 inch, can be tack welded to the top of the adjustment ring, under the location each clamping cylinder. It is then necessary to source and install correspondingly longer tube spacers. This will allow increased vertical travel that will take up the additional clearance between the worn bowl and adjustment ring threads, and thus reestablish a proper bowl lock.

Eblast Shims Call Out Excel Expertise: Eliminate Excessive Bowl Movement in Your HP700™ Cone Crusher

Due to the progressive wear to the bowl threads (less wear the higher up the bowl) and adjustment ring threads (less wear the further into the adjustment ring), it is not possible to compensate for the maximum thread wear of the initially engaged threads. That is, using too much shim spacer could result in a lack of clearance between the less worn threads, causing the bowl and adjustment rings to potentially lock together. The amount of shim spacer used will depend upon the size of the crusher and the design travel of the clamping ring. Please contact Excel for additional instructions before attempting this procedure.

The Excel supplied aftermarket clamping cylinder (9307-0001-XLHS) has 10 millimeters of piston travel more than the OEM supplied clamping cylinder. With the HP700™ (and HP800™) crusher, it is possible to replace the original 16 clamping cylinders with the Excel clamping cylinders and add four, approximately 7.5 mm longer tube spacers. With this arrangement, it will not be necessary to add shims under the clamping cylinder. The longer tube spacers will provide more travel than would ever be possible without the bowl and adjustment threads starting to break up; however, this additional travel will ensure that full clamping forces are available up until the time the bowl and/or adjustment ring is sent out for thread repair.

There are other possible causes of bowl movement besides worn bowl and adjustment ring threads. Inadequate locking of the bowl can be caused by air trapped in the clamping hydraulic circuit and clamping cylinders. The cyclic crushing forces can cause the clamping pressure to fluctuate due to the compressibility of the air. Bowl movement may also be related to using thicker liners (mantle and bowl liner) than what the crusher was originally designed for. Thicker liners will usually require a different bowl with more thread turns, and a change in dust shell. Of course, all of these issues are made worse by excessive ring bounce.

-Ken Olson, Excel Service Manager

Ken Olson200 Excel Expertise: Eliminate Excessive Bowl Movement in Your HP700™ Cone Crusher

With over 30 years of experience in the mining industry and a degree in mining engineering, Ken Olson is a leader in the field. He helped develop the Raptor Cone Crusher line after joining Excel Crusher Technologies in 2004, and after joining Excel Foundry & Machine in 2012, he has been using his vast experience to greatly help the Excel team ever since.

Excel provides premium aftermarket components for more than a dozen different OEM brands. At Excel, we believe in delivering our distributors and customers quality products along with providing the very best in service and experience from industry experts.

HP® is a mark of Metso Corporation or its affiliates. Excel Foundry & Machine is not an authorized repair facility nor does it have an affiliation with Metso. These terms are used for identification purposes only and are not intended to indicate affiliation with or approval by Metso of Excel. All parts are manufactured by, for and warranted by Excel Foundry & Machine and are not manufactured by, purchased from or warranted by the original equipment manufacturer.

 
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