This invention relates to a hand tool having a handle, such as screwdrivers and other hand tools which may have replaceable tool-bits.
A large variety of fastening screws of various sizes, with different head types, e.g. slotted, Phillips, and Posidriv, are in use nowadays. These require a corresponding variety of screwdrivers or screwdriver bits. Bits may be selected from a storage unit and transferred to the chuck of a hand tool such as a cordless motorized screwdriver. The user has to remember to return the bits to the storage unit. It is inconvenient to use a succession of different bits at a location remote from the storage unit.
There are a large number of multi-bit screwdrivers on the market. Many of these store the bits loosely in a compartment in the handle, in which the bits may rattle noisily. In order to locate a particular bit it is usually necessary to removal all the bits from the compartment and to sort through them. Other multi-bit screwdrivers have the bits attached releasably to the front of the handle, in which case they are easily dislodged inadvertently.
US-A- 4 273 173 discloses a hand tool in accordance with the pre-characterising part of claim 1. The hand tool disclosed has a tool-bit magazine with a body, integral with a handle, a sleeve rotatable to a position in which an aperture in the sleeve is in register with a recess in the body and thereby permits a tool-bit to be removed from or inserted into that recess.
The present invention provides a hand tool as set forth in claim 1.
The invention will be described further, by way of example only, with reference to the accompanying drawings, in which:
The screwdriver has a steel bar or shaft 1 which extends from one end of a composite plastics handle 2 having a hard polypropylene core. The bar is press formed with two longitudinal ribs (not visible) which retain the shaft 1 in the handle after the shaft has been pressed into the handle. The distal end of the shaft has a hexagonal recess 3 for receiving the hexagonal stub of a conventional tool-bit. A permanent magnet 4 is fixed in the base of the hexagonal recess 3 in order to retain the bit in use.
A tool-bit magazine 6 is mounted on the proximal end of the shaft 1. It has a body 7 with peripheral elongate recesses 8 for accommodating tool bits 9, one of which is visible in Figure 1. The recesses 8 are spaced around the common axis 11 of the shaft 1 and the body 7 and they extend generally in the axial direction.
The body 7 has an axial bore 12 which is a sliding fit on the shaft 1. A radially inwardly projecting portion 13 of the body 7 engages in a circumferential groove 14 machined in the shaft 1, in order to retain the body 7 on the shaft 1. A bevel 13a on the inside edge of the projecting portion 13 allows the body 7 to be pushed on to the shaft 1. The rear end surface 16 of the body abuts against the front end surface 17 of the handle. The front end of each recess 8 is defined by a wall surface 8a sloping outwards away from the other end, which is open and which is covered by the front end surface 17 of the handle.
A sleeve 18 prevents escape of the bits 9 from the recesses 8. The sleeve 18 is mounted in a circumferential recess 19 in the body 7 so as to be rotatable to respective positions in which an aperture constituted by an open-ended slot 21 in the sleeve 18 is in register with a respective one of the recesses 8, thereby permitting a bit 9 to be inserted into that recess or removed from that recess (by allowing it to fall out under gravity). Since both the body 7 and the sleeve 18 are rotatable relative to the rest of the tool, it is necessary to hold one of them with one hand while the other hand rotates the other of them. For facilitate this, the body 7 and the sleeve 18 are provided with external ribs 7a and 18a respectively. Since the whole magazine 6 is rotatable, the shaft 1 can be guided firmly by one hand while the other hand rotates the handle 2, without any risk of the sleeve 18 being turned independently of the body 7 and inadvertently freeing the bits during use of the screwdriver.
As can be seen from Figure 1 particularly, the sleeve 18 only covers about half of the length of the recesses 8, with the result that the front ends of the bits 9 are visible so that they can be easily identified and selected. The rear end of the bit 9 rests against the front end surface 17 of the handle 2 and its tip rests against the sloping surface 8a. Rattling of the bits 9 in the recess 8 is prevented by flanges 22 which are formed integral with the body 7 and which are resiliently deformed by the bits 9 so that the bits are retained between the flanges 22 and the sleeve 18. As shown in Figure 3, the hexagonal stub of the bit 9 is able to adopt different angular positions, two of which are indicated in solid line and chain line respectively.
In order to enable the sleeve 18 to be indexed and located in the respective positions in which the slot 21 registers with the respective recesses 8, a spring loaded ball 23 mounted in a radial bore in the body 7 cooperates with a circumferential series of part-spherical notches 24 in the sleeve 18.
Various modifications may be made within the scope of the invention. For example, a reversible ratchet mechanism for transmitting rotation from the handle 2 to the shaft 1 may be interposed between the magazine 6 and the handle 2.
Figures 4 to 6 show a preferred embodiment of the screwdriver, in which parts similar to those described above are given the same reference numerals. The screwdriver has a tool-bit magazine 6 with a body 7 having recesses 8 accommodating tool bits 9. The body 7 has an axial bore which is a sliding fit on the shaft 1. A portion 13 of the body 7 engages in a circumferential groove 14 machined in the shaft 1. A sleeve 18 is mounted in a circumferential recess 19 in the body 7 so as to be rotatable to respective positions in which a slot 21 is in register with a respective recess 8, to permit insertion or removal of a bit 9. A spring loaded ball 23 mounted on the body 7 engages in a circumferential series of notches in the sleeve 18
The screwdriver shown in Figures 4 to 6 also has a ratchet mechanism 51 between the magazine 6 and the handle 2. The ratchet mechanism has a body 62 with a bore 56 receiving the shaft 1 which is formed with a spur gear 57 engageable by pawls 58a and 58b which are tiltable about axes parallel to the shaft axis 11. A control sleeve 64 is linked to a control member 66 carrying a leaf spring 76 with legs 76a and 76b which bear on the pawls 58a and 58b respectively. The control sleeve 64 is movable clockwise and anticlockwise from the intermediate position shown in Figure 6, in which both pawls 58a and 58b and engaged with the gear 57, to respective ratcheting positions in which only one or the other of the pawls is engaged with the gear 57.
The rear end surface 16 of the magazine body 7 abuts against the front surface of the body 62, against which the rear ends of the bits 9 rest. The tips of the bits 9 rest against sloping front end surfaces 8a of the recesses 8.
The ratchet mechanism 51 is described in more detail in our U.K. Patent Application No. 9816878.4 filed 3 August 1998, published as GB-A- 2 340199 on 16 Feb 2000.