EP0234066B1

EP0234066B1 - Apparatus for hand drilling

Info

Publication number: EP0234066B1
Application number: EP19860300361
Authority: EP
Inventors: Karl Arne Karlsson
Original assignee: Individual
Current assignee: Karlsson Karl Arne
Priority date: 1986-01-20
Filing date: 1986-01-20
Publication date: 1989-11-23
Also published as: DE3667034D1; EP0234066A1

Description

The present invention relates to an apparatus for use with a portable hand-drill, according to the precharacterizing part of claim 1. Such an apparatus is known from US-A 4 082 474.
Portable hand-drilling operations in the field, for example at a construction site, have been known to suffer certain drawbacks stemming from difficulty in controlling the drill, particularly heavy drills, and difficulty in holding the workpieces. These problems not only can affect accuracy, quality and rate of production but they also seriously risk the safety of the drill operator.
During drilling operations with a portable hand-drill, a reaction torque is generated in the drill and it is thus necessary for the drill operator to resist this torque with his body in order to hold the drill steady and to prevent rotation of the workpiece. This problem becomes acute with heavy or large hand drills because the reaction torque can be great enough to strain the operator's hands, arms, shoulders or back. Moreover, if the drill cannot be steadied by the operator, the workpiece can rotate out of control causing a safety hazard while frustrating the drilling operation.
In order to combat the aforementioned problem, it is often necessary to drill holes at the same location in successively larger sizes (until the desired size is reached) in order to reduce the generated reaction torques. This, of course, seriously slows the rate of production and increases costs.
Other attempts to overcome the problem utilize magnetic devices for holding the drill in the proper position. However, such devices are heavy, cumbersome and costly and therefore are not readily available at job sites.
US-A 4 082 474 refers to a drill attachment device including a frame for mounting on a drill motor, guide sleeves on said frame, and guide rods mounted on a base plate. The base plate is placed on a workpiece to be drilled. The object of this device is to aid in accurately locating and drilling desired openings and holes in a workpiece and especially at different angles. According to one embodiment of this prior art device it also has "free ends" protruding underneath the base plate. The object of these are to allow for an exact centering of a hole in the workpiece. The guide rods might be used without the base plate, provided that a rigid type of frame is used for securing the guide sleeves on the drill motor. The distance between the guide rods is fixed.
US-A 2 990 732 refers to a drill guide and hole setter for hand drills comprising an elongated shaft spaced in parallel relation with respect to the drilling element and being insertable in a drilled hole, a gauging element supported from the body of the hand drill, a support means comprising an elbow-shaped housing with two arms, in which the gauging element resp. the shaft are slideably supported.
To avoid the problem caused by a rotating workpiece, vices have been used. However, the problem of torque stress exerted on the operator's body still persists which can cause serious injury. Moreover, the use of vices seriously slows operations because for each drilling operation, the vice must be loosened, relocated and reset.
It is a primary object of the present invention to provide an apparatus for conducting hand-drilling operations with ease, accuracy and safety and which overcome the aforementioned problems. Included herein is such an apparatus which diverts stress from the drill away from the operator's body, while holding the workpiece in fixed position without a vice, for safe and efficient drilling.
A further object of the present invention is to provide such apparatus that may be manufactured either as a portable attachment for conventional or new hand drills of various designs or as part of the hand drill itself. Included herein is the provision of such apparatus that possesses relatively few parts that may be economically mass produced for retail at relatively low cost and yet will be reliable over long periods of repeated use without breakdown to improve hand drilling performance and safety.
According to the present invention there is provided an apparatus for use with a portable hand drill having a body, comprising an elongate rigid load transfer member having a free end and means, affixable to the body of the hand drill for mounting the hand drill on said load transfer member such that the free end of the load transfer member may be placed against a workpiece to be drilled during a drilling operation to transfer torque through the load transfer member to the workpiece without attaching the load transfer member to the workpiece, characterised in that the means for mounting the hand drill on said load transfer member comprises a holder formed by a tubular steel member having a rectangular cross section and an arm formed by a steel bar of rectangular cross section, corresponding to that of the internal passage of holder to be slidable therein into any desired position, the arm at one end being fixedly mounted on the hand drill body and the load transfer member being slideably but lockably received in a sleeve member, forming part of holder.
In accordance with the present invention, a hand drill is held in a holder which may be mounted for movement along a load transfer member which may be termed a "jack". Where the workpieces to be drilled are of a discrete size, the jack is located to extend alongside of the workpiece so that the torque generated in the workpiece will tend to cause the workpiece to rotate against the jack while the equal but oppositely directed reaction torque will be transferred from the drill through the jack and into the workpiece, thus tending to rotate the jack against the workpiece. Since these torques are equal in magnitude but oppositely directed, the result will be that the workpiece is held stationary against the jack and vice versa. In addition, the reaction torque is diverted from the operator's body and transferred back to the workpiece.
If the object to be drilled is of very large size or indiscriminate in dimension, the jack may be anchored against another object or against the foot of the operator to divert stress from the upper part of the operator's body.
in cases where the jack is not grounded on a surface during drilling the holder may be tightly fastened to the jack so that they move together as a unit with advancement of the drill.
The holder may be made as a portable attachment to the hand drill or as a part of the body of the hand drill. For large hand drills, two holders and jacks may be employed respectively on diametrically opposite sides of the hand drill.
By way of example only, specific embodiments of the present invention will now be described, with reference to the accompanying drawings, in which:

Fig.1 is a side elevational view of apparatus, constituting one preferred embodiment of the present invention, as seen with a workpiece, shown in fragment, and as seen partly in dotted lines illustrating another position into which the apparatus may be adjusted;
Fig.2 is a view generally similar to Fig.1 except with the positions of certain parts of the apparatus interchanged to accommodate a workpiece of smaller length and with upper portions of the hand drill removed;
Fig.3 is a cross-sectional, plan view taken along lines 3-3 of Fig.1;
Fig.4 is a view generally similar to Fig.3 with parts removed, illustrating oppositely directed torque forces encountered during a drilling operation;
Fig.5 is a side, elevational view of apparatus constituting another preferred embodiment of the invention as seen with another, smaller type of hand drill than that illustrated in Fig.1;
Fig.6 is a plan view of the apparatus of Fig.5 but excluding the hand drill; and
Fig.7 is a view similar to Fig.6 but with a portion of the apparatus reversed in position for accommodating a workpiece (not shown) of greater length.

Referring now to the drawings in detail there is shown in Figs. 1 to 4, a first preferred embodiment of the invention that may be applied to a portable hand drill designated 10 in Fig.1. Hand drill 10 itself may be any conventional hand drill for drilling holes in a workpiece W as shown in Fig.1 resting on a surface 11. Hand drill 10 typically includes a chuck 14 for holding a rotary cutting tool or bit 12. The chuck 14 is rotatable by a motor in the drill housing, driven by power fed through a power cord 16 and controlled by a trigger 17 lying below a handle 18. Additional handles 20 and 22 are also incorporated. In conventional drilling operations the operator grasps handles 18 and 20. However, due to the reaction torque generated in the drill 10, the operator must often exert great effort to prevent the drill 10 from rotating, which torque may also cause rotation of the workpiece W. This can cause serious injury to the operator and at the same time, impede or frustrate the efficiency of the drilling operation.
In accordance with the present invention, a method and apparatus are provided to overcome the aforementioned problems in a manner that is easily applicable to conventional hand drills. The apparatus includes at least one load transfer member designated 30, and means for mounting or connecting the hand drill 10 to the load transfer member 30 as will be described in greater detail below. In the preferred embodiment of Fig.1, there are two load transfer members 30 (which may also be termed "jacks") each in the form of a sturdy, rigid pipe or rod of steel or other suitable material located laterally of the drill 10 at diametrically opposed locations. The means for mounting the drill 10 to each jack 30 in the specific embodiment shown in Fig.1 comprises a holder designated 40, and an arm 50 fixed to the hand drill 10 and received by the holder 40. Although it is possible to form the arm 50 as an inseparable part of the drill 10 itself, it is preferred to form the arm 50 as part of a yoke 52 or other similar means that may be releasably secured to the body of drill 10 as shown in Fig.1.
In the preferred embodiment, shown in Fig.3, holder 40 is formed by a tubular steel member having a rectangular cross section and having a through passage 46 extending to opposite, open ends of the holder 40. Arm 50 is formed by a steel bar of rectangular cross section, corresponding to that of the internal passage 46 of holder 40, to be slidable therein into any desired position. Arm 50 may be formed as an integral part of yoke 52 or may be welded thereto so that it rigidly projects laterally therefrom. Yoke 50 may take any desired form that will enable fixation to the body of the drill 10. In the specific form shown, yoke 52 is in the nature of a C clamp or shackle which is dimensioned to encircle the pertinent portion of the body of the drill 10 which portion is shown as cylindrical in shape and located in the region above the chuck 14. Yoke 52 terminates in apertured flanges 56 secured together by a nut and bolt assembly 57,58. It will be obvious that other yokes and yoke shapes may be employed depending on the size and shape of the associated drill body. Moreover, other types of methods and means may be employed to interconnect the drill body to the associated jacks 30.
In order to secure arm 50 to the holder 40 in any desired position therein, any suitable releasable fastening device or means may be employed. One simple method is to utilize a thumb screw or set screw such as 60 (Fig.3) threaded through the wall of holder 40 so that its internal extremity engages against the arm 50. A wrench may be applied to the head of screw 60 to sufficiently tighten it against arm 50.
In order to mount holder 40 to the associated jack 30, the preferred embodiment includes a sleeve-like member 42 fixed, such as by welding to one side of the holder 40. Sleeve-like member 42 has a vertical through passage for slidably receiving jack 30 to permit the holder 40 to slide downwardly along the jack 30 as the drill 10 advances during a drilling operation, in cases where the lower end of the jack 30 is engaged or grounded against a surface such as 11. In order to control the position and movement of holder 40 along jack 30, a releasable fastening device is employed to exert a desired degree of pressure against the jack 30. Here again, a simple set screw or thumb screw 44 is utilized in the wall of the sleeve-like member 44 to be engageable with jack 30 to control the movement of holder 40 along jack 30 during a drilling operation where the end of the jack 30 is grounded against a support surface. However, in some uses, the extremity of jack 30 adjacent of the workpiece W will not be grounded on a support surface such as 11 in which case the screw 44 may be tightly fastened against the jack 30 so that the holder 40 and jack 30 will move together as a unit with the drill 10 as the latter advances during drilling. To assist in retaining the jack 30 in the sleeve member 42 against accidental removal, the jack 30 is provided with a cap 32 larger in diameter or cross dimension than that of the internal passage of sleeve member 42.
Both of the jacks 30 and holders 40 utilized in the embodiment of Fig.1 are identical. Moreover, their positions may be changed, for example, from that of Fig.1 to that of Fig.2, in order to reduce the distance between the jacks 30 and so to accommodate workpieces of smaller length such as W1 shown in Fig.2. The open opposite ends of the holders 40 allow the arms 50 to be inserted through either end of the holder as may be required. The dotted lines in Fig. 1 illustrate a position of jacks 30 that may be used for a larger workpiece.
In use of the apparatus, and with reference to Fig.3, the holders 40 with their jacks 30, are positioned on the arms 50 with jacks 30 located on opposite sides of arms 50. Holders 40 are then slid along arms 50 into the desired position depending on the length of the workpiece W and with jacks 30 equidistant from the centre of the drill or bit 12. Once the holders are adjusted into proper position, screws 60 are then fastened against arms 50 to secure the latter in holders 40. The drill 10 may then be positioned to place the jacks 30 on opposite sides of the workpiece W as shown in Fig.3. The operator may then grasp handles 18 and 20 or 18 and 22 and commence drilling.
Referring now to Fig.4, arrow 70 illustrates the direction of rotation of drill bit 12. A torque will be generated in the workpiece W in a direction indicated by arrows Ti. A reaction torque will be generated in drill 10 but this torque will be transferred from drill 10 through jacks 30 and into the workpiece. The reaction torque is indicated by the arrow T₂ in Fig.4. As the torques T₁ and Tε are equal and oppositely directed, the workpiece will be held stationary against the sides of jacks 30 and vice versa. Moreover, the torque generated in drill 10 will be diverted away from the operator and back into the workpiece W. The result is a smooth and efficient drilling operation with no harmful torque stress received by the operator.
Referring now to Figs. 5 to 7, there is illustrated another preferred embodiment of apparatus of the invention which may be applied to a conventional hand drill 80 that is of a smaller size than hand drill 10 of Figs. 1 to 4. Hand drill 80 itself may be conventional and includes a handle 81 and a control button or trigger 83 for controlling the motor which is housed within the drill 80. The apparatus of the present invention in the embodiment of Figs. 5 to 7 includes a holder 82 similar to holder 40 described above and including a through passage 84 and a sleeve 86 for receiving a jack 30. In the specific embodiment, sleeve 80 is fixed to the side wall of holder 82 by a bracket 87 which may be welded to holder 82. A thumb screw 88 is provided through the bracket 87 and sleeve 86 to be engageable with jack 30 to fix or control its position.
Slidably recieved in holder 82 is an arm 90 which is held in any desired position by thumb screw 91. In the specific embodiment, holder 82 is provided with another threaded opening at 92 (see Fig.5) for receiving thumb screw 91.
Arm 90 is fixed to a yoke 94 which in the specific form includes a continuous polygonal enclosure made from any suitable sturdy material and shaped to correspond to the external shape of the drill 80 above the chuck 79. Specifically, yoke 94 includes a front wall 95, a rear wall 96 generally parallel to the front wall 95 and opposite side walls 97 defining a cavity for receiving the drill 80. Arm 90 projects laterally from front wall 95 at the centre thereof where it may be integrally joined or welded.
In order to secure the drill 80 within yoke 94, the front wall 95 has a flange 98 projecting upwardly therefrom to extend along the casing of the drill 80 as shown in Fig. 5. A bolt 99 is received through a threaded aperture in flange 98 for engagement against the housing of the drill 80 as shown in Fig.5. Advancement of bolt 99 will secure the drill 80 within the yoke 94. Even though only a single jack 30 is used in the embodiment of Figs. 5 to 7, the principle of operation is the same as described above. That is, the torque generated in the drill will be transferred to the jack 30 and back to the workpiece which is held in place against the side of the jack 30.
In drilling large workpieces where the side of the jack 30 cannot be placed against the workpiece, another support (not shown) may be used to anchor the jack 30 to transmit reaction torque to the support. In some cases, the operator may take place the jack 30 against his foot to steady the drill and divert stress away from his arms. In cases wherein the end of the jack 30 is not grounded against a support but still engages the side of the workpiece, the jacks 30 are secured within the sleeves 42 so that they will advance with the drill as the drilling proceeds.
It can be seen that the presnt invention may be used in drilling large or small workpieces without subjecting the operator to harmful torque stress.

Claims

1. Apparatus for use with a portable hand drill (10) having a body, comprising an elongate rigid load transfer member (30) having a free end and means, affixable to the body of the hand drill (10) for mounting the hand drill on said load transfer member (3) such that the free end of the load member may be placed against a workpiece (W) to be drilled during a drilling operation to transfer torque through the load transfer member (30) to the workpiece (W) without attaching the load transfer member (30) to the workpiece (W), characterised in that the means for mounting the hand drill (10) on said load transfer member (30) comprises a holder (40) formed by a tubular steel member having a rectangular cross section, a yoke (52) to be fixed around the hand drill body, and an arm (50) formed by a steel bar of rectangular cross section, corresponding to that of the internal passage (46) of holder (40) and being slidably received therein in a desired position, the arm (5) at one end being fixedly mounted on the yoke (52) such that it projects laterally from the hand drill body and the load transfer member (30) being slideably but lockably received in a sleeve member (42), forming part of holder (40).