Tool driving or impacting – Impacting devices – With impact cushioning means
Reexamination Certificate
1999-11-06
2001-07-10
Smith, Scott A. (Department: 3721)
Tool driving or impacting
Impacting devices
With impact cushioning means
C173S089000
Reexamination Certificate
active
06257352
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is drawn to a device for breaking rocks. More specifically, the present invention is drawn to a device for breaking rocks which has a recoil assembly and a cushioned tool holding structure. For the purposes of this application, the term “rock ” may be taken to include, rocks, stones, ores, construction materials, or the like.
OBJECTS OF THE INVENTION
Most devices for breaking rocks utilize a massive weight that is allowed to fall under the influence of gravity to impact a tool that is driven into the rock to break it. The forces imparted by repeated heavy blows from a weight being used to drive a tool can easily exceed the maximum allowed stresses in the materials from which typical rock breaking devices are made, e.g. steel and cast iron. In an effort to alleviate this problem, elastomeric cushions or buffers of rubber, leather, and even wood are placed around a rock breaking tool to cushion the blow of the weight on the tool. However, there is a problem with simply placing an elastomeric cushion or buffer between a falling weight and a tool. When a weight vertically compresses a buffer or cushion, the buffer or cushion responds by expanding laterally. Where this lateral expansion comes into contact with the side walls of a rock breaker, the force exerted upon the side walls of the rock breaker by the cushion or buffer may deform and even break the side walls of the rock breaking device. Furthermore, it often happens that a weight is allowed to drop within a device for breaking rocks when there is no object beneath the tool or where there is no support for the tool itself. In this case the entire force of the falling weight will impact sharply against the tool and the lower end of the rock breaking device in a destructive manner. This situation is called “bottoming out” in that the weight strikes the bottom of the rock breaking device rather than the force of the impact being transferred through the tool to a rock. Bottoming out a rock breaking device even once can cause severe damage to not only the rock breaking device but to a vehicle or stand to which the device is attached.
Therefore, its an objective of the present invention to provide a recoil buffer that is located outside of the main guide column or mast within which the weight or ram travels. In this manner, the force imparted to the rock breaking device may be cushioned and any damage to the rock breaking device will be directed to a component of the device that may be readily replaced rather than to the guide column or mast which is often the back bone of a rock breaking device.
Another object of the present invention is to provide a resilient isolating structure which will prevent damage to the rock breaking device and especially to the mast or guide column of the device when the weight is allowed to bottom out.
SUMMARY OF THE INVENTION
The device for breaking rocks of the present inventions comprises a hollow tubular mast having a top end and a bottom end and a channel formed therethrough from the top end to the bottom end. A weight for delivering an impact travels through the channel of the mast between the top and bottom ends thereof. A weight raising mechanism is coupled to the weight so as to raise the weight from the bottom end of the mast to the top end of the mast. The weight raising mechanism is further capable of releasing the weight so that the weight may fall under the influence of gravity to the bottom end of the mast. An attachment structure is welded to the mast to secure the rock breaking device to a vehicle, or alternatively, a stationary rock breaking structure.
In one embodiment of the present invention, a recoil assembly is mounted to the bottom end of the mast which comprises a plurality of isolator structures secured to the mast at a predetermined distance from the bottom end of the mast. The isolator structures support a recoil tube in resilient telescoping relation to the mast with the recoil tube being received over the mast. A tool holding structure comprising a nose block having a tool for striking rock slidably received in a bore formed therethrough is mounted to the lower end of the recoil tube. The tool received in the nose block is generally cylindrical and has a flat formed into a side thereof so that a retaining pin passing through the nose block will intersect the bore in the nose block. The pin also intersects the flat formed into the tool and thereby limits the travel of the tool within the nose block. An upper surface of the tool may extend above an upper surface of said nose block into a space that is bounded by the bottom end of the mast, the upper surface of the nose block, and by the inner walls of the recoil tube. A lower surface of the tool extends below a lower surface of the nose block and is free to be placed in contact with a rock that is to be broken. The lower end of the tool may be shaped in any desirable manner including but not limited to flat, rounded, pointed, and chisel shaped.
In this first embodiment, a recoil buffer is disposed within the space bounded by the bottom end of the mast, the upper surface of the nose block, and by the inner walls of the recoil tube. The recoil buffer has a bore formed therethrough in registration with the bore of the nose block such that the tool may slidably pass through both bores, with the upper surface of the tool being capable of being positioned above the upper surface of the recoil buffer. In this manner the weight delivers an impact to the upper surface of the tool when the weight is released to fall to the bottom end of the mast. The impact of the weight upon the tool will drive the upper surface of the tool downward and below the upper surface of the recoil buffer such that the weight will then come into contact with the recoil buffer. The elastomeric recoil buffer then absorbs and dissipates the impact forces of the weight that have not been transferred to the tool by elastically deforming in a known manner.
A reinforcing structure may be disposed within and affixed to the inner surface of the recoil tube around the recoil buffer. The recoil buffer and the reinforcing structure are sized so as to create a gap between the periphery of the recoil buffer and the reinforcing structure. In one embodiment of the present invention the gap is approximately ⅜″.
The isolator structures in one embodiment comprise a bracket which opens towards the top end of the mast. The bracket has substantially parallel side plates affixed to the mast and a bottom plate affixed to the mast and to a bottom edge of the side plates. The bracket is sized to receive and retain an elastomeric isolator buffer with a cover plate arranged to be placed over the isolator buffer in the bracket. The cover plate, the isolator buffer and the bottom plate all have at least one bolt hole bored therethrough to permit at least one connecting bolt to be passed through each of the plurality of isolator structures. The connecting bolts are passed through bolt holes bored through an upper flange affixed to an upper end of the recoil tube and preferably secured with a nut. The upper flange of the recoil assembly is resiliently biased into contact with a lower surface of the plurality of isolator structures by the connecting bolts such that when impact forces are applied to the recoil tube so as to force the recoil tube downward with respect to the mast, the connecting bolts bear down on the cover plates which in turn compress the isolator buffers in a resilient manner. The isolator buffers regain their original dimensions when the impact forces have been dissipated.
The recoil assembly further comprises a lower flange that is affixed to the lower end of the recoil tube. This lower flange is provided with a plurality of bolt holes for securing the nose block to the recoil tube. In addition, the recoil assembly further comprises a plurality of plate shaped reinforcing gussets that are affixed to the outer surface of the recoil tube and to the upper and lower flanges so as to increase the stiffness of the
Moore & Hansen
Smith Scott A.
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