In the past there has been a considerable need for a drilling machine which provides the capability of drilling accurately positioned and straight large diameter holes in a horizontal direction in vehicle chassis frames and other objects. This has been especially true in construction-type vehicles or equipment which has a number of pivoting or articulated joints which need to be repaired or replaced at various times. In order to be able to drill, tap or ream these holes it is necessary to provide a stable platform for the electric or air driven drill motor so that the desired accurate results can be obtained.
In the drilling of large diameter holes common in industrial or construction-type applications, the large size drill motor which is required is too heavy and cumbersome to be handled manually and supported by one or two operators during the drilling process. Because of this it is mandatory that a drill motor of this size be suitably supported by an auxiliary device for holding the drill motor during the drilling operation. One of the devices which has been provided in the past is a magnetic support or base upon which the drill motor is mounted. This mount assembly includes a rack and pinion feed arrangement for moving the drill in relation to the surface which is being bored.
The magnetic base support is usually of the electromagnetic type so that the base and drill can be properly positioned before the magnets are energized to lock the base in position. When the drilling operation is complete, the removal of the electric current from the electromagnet releases the base allowing the drill to be repositioned or moved. In the past there have been some problems with the holding strength of the electromagnet in a device of this nature because of size and weight limitations. Usually a safety chain is attached to some structure above the device so that if the drill should come loose it will not fall and injure the operator.
Another of the problems with a magnetic drill support of this type is its inability to securely attach to a surface which has some irregularities, corrosion or curvature. Another critical limitation is the inability of the base to attach to a nonferrous material such as plastic, aluminum or copper. Thus, when drilling through these types of materials it is impossible to utilize this type of support.
Another type of drill support which has been utilized in the past is a clamp base. With this type of drill base, a clamp such as a "C" type having an extended screw or lever is positioned to grip the flange or beam upon which the drilling is to be accomplished. After positioning the drill base in the proper location the lead screw or lever is tightened to clamp the base in this position. Again, similar to the magnetic type base, it is time consuming to hand support and maneuver the drill base into proper position and tighten the clamp and then reverse the process after the drilling operation has been completed.
Where it is necessary to line bore loader bucket arms or dump bed hinges it has been found that because of the distance between the hinge points which can be as much as three to five feet it is extremely difficult to accurately drill and ream these apertures by hand. For this reason, in many cases the eye or hinge points have to be cut off of the vehicle or equipment and line bored on a separate lathe or vertical mill. Even after this process has been completed it is difficult to reweld these parts to the vehicle and again provide the necessary alignment. This repair process is naturally very expensive and is accomplished with even a greater cost when considering the down time for the equipment itself during this process.
The present invention is intended to eliminate many of the problems which have been described herein. It has been found that any time it is necessary to drill a number of precisely positioned or aligned holes in a vehicle or object which is relatively close to the ground, it is desirable to be able to support the drill from the floor or adjacent support surface. By making the drill mobile and supported on this surface, it is easy to shift the drill and perform a number of drilling operations in a short time. In addition, it is easy for a single operator to manage the drilling operation without fatigue since the weight of the drill is supported for him. Thus, the heavy lifting and maneuvering of the drill motor during a number of drilling operations can be completely eliminated with the applicant's invention.
The portable or mobile horizontal drill press described herein is ideally suited for drilling a number of precisely positioned holes in the side of a truck chassis for installation of a quick change coupling arrangement. The quick change coupling kit is the subject of my copending patent application, Ser. No. 344,833, which describes a new and novel arrangement for securely attaching a truck body or other equipment to the chassis of a truck vehicle. To accomplish the installation of this coupling kit, it is necessary to precisely drill a number of large diameter holes in the vertical side surface of the chassis beams. To perform this installation a portable horizontal drill having a long reach and span is extremely useful. By the same token this same portable drill can be used for drilling or boring apertures in all types of large equipment, vehicles or accessories such as axle housings, battery boxes and fuel tanks.