Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING OR HOLDING
  • B25B15/00—Screwdrivers
  • B25B15/001—Screwdrivers characterised by material or shape of the tool bit
  • B25B15/004—Screwdrivers characterised by material or shape of the tool bit characterised by cross-section
  • B25B15/005—Screwdrivers characterised by material or shape of the tool bit characterised by cross-section with cross- or star-shaped cross-section

Definitions

• the invention relates to a screwdriver according to the preamble of claim 1.
• Cross slots for screws have been standardized in the form of the so-called Philips cross slots for several decades (DIN 7962 from 1959; ASA B 18 from 1958 and BS 450 from 1958). More recently, so-called Pozidrive cross slots have also become established. It has become common for screws whose cross recess to be spoiled when tightened to be loosened and, if necessary, tightened again. Screws with a cross recess, for example in accordance with DIN 7962, are additionally provided with a diametral slot, for example in accordance with DIN 84.
• Screws with such slot arrangements which are known under the name "plus-minus cross recess" are normally tightened with a cross recess screwdriver with a cross recess screwdriver and, if necessary, also loosened again; in the event of the cross slot being destroyed, a screwdriver with a simple bridge is used.
• Cross slots for screws are divided into five size classes with the designations 0 to 4 according to DIN 7962.
• the torque that a screwdriver has on an axial Can transmit pressure of 4N to a Phillips screw depends on the size class of the Phillips and is, for example, 1.2 Nm for the Phillips size 1, which is common for screws with thread sizes M3.5 and M4.
• the torque which can be transmitted with conventional Phillips screwdrivers can only be increased within narrow limits by increasing the axial contact force, with the Phillips size 1 at best to 1.6 to 1.7 Nm; Even then, damage to the cross slots of the screws increases and the service life of the screw drivers decreases accordingly.
• a screwdriver for screws which has a diametrical slot with a centrally arranged funnel-shaped extension.
• the screwdriver has a cross-shaped profile with a longer and a shorter pair of legs.
• the longer one Pair of legs forms a diametral bar for engaging in the diametrical slot of a screw; the shorter pair of legs, being receding from the center of the diametral web, is sloping in the shape of a roof and provided for engaging in the funnel-shaped enlargement of the diametrical slot.
• the shorter pair of legs engaging in the funnel-shaped expansion of the diametrical slot prevents the longer pair of legs from slipping in the diametral slot.
• the shorter pair of legs cannot contribute to centering either. There is therefore a risk that the screwdriver will slip off the head of the screw.
• the invention has for its object to develop a screwdriver for screws with a cross recess and an additional diametral slot - so-called plus-minus cross recess - in such a way that it achieves a satisfactory service life even when loaded with the largest torque permissible for screws of the appropriate size.
• the screwdriver according to the invention is expediently developed according to claim 2.
• the base level facilitates the tilt-free placement of the screwdriver on a screw.
• the base plane is preferably arranged in such a way that after the screwdriver has been placed on a screw, it has a distance of approximately 0.05 to 0.15 mm from the end face of the screw and is therefore not subject to the transmission of axial forces from the screwdriver to a screwdriver Screw is involved, the plus-minus cross slot is within the usual tolerance ranges.
• the invention is suitable for screwdrivers which are provided with a handle for manual operation, in the same way as for screwdrivers in the form of an insert (bits) for electrically or pneumatically driven screwdrivers.
• each of the two screwdrivers shown has a cylindrical shaft 10, the axis of which is designated A.
• the shaft 10 ends in a base plane 12 normal to the axis; from this rises a diametrical web 14, the length of which, measured at right angles to the axis A, corresponds to the diameter of the base plane 12.
• the thickness of the diametral web 14 steadily decreases with increasing distance from the base plane 12; the two longitudinal flanks of the diametral web 14 facing away from each other are inclined at an angle of 5 ° to the axis A.
• a longitudinal web 16 adjoins the diametral web 14 in the central region of its total length, which forms a continuation of the diametral web and has longitudinal flanks, each with one of the longitudinal flanks of the diametral web 14 inclined by 5 ° with respect to the axis A in one Level.
• the longitudinal web 16, measured from the base plane 12 is approximately half the height of the diameter web 14 higher than this.
• the diametral web 14 has a height of 1.6 mm, measured from the base plane 12, while the longitudinal web 16, likewise measured from the base plane 12, has a height of 2.5 mm.
• a transverse web 18 extends at right angles to the longitudinal web 16 and, together with the longitudinal web 16, forms a cross-shaped elevation 20.
• the transverse web 18 begins at the base plane 12, measured from this, has the same height as the longitudinal web 16 and has a thickness which, in the same way as that of the longitudinal web, increases with increasing distance from the base plane 12 at an angle of 5 ° the axis A decreases.
• the two webs 16 and 18 of the cross-shaped elevation 20 are both rounded in the same way; they are delimited by a common spherical surface, the center M of which is also the center of the base plane 12.
• the two webs 16 and 18 of the cross-shaped elevation 20 have trapezoidal profiles which, in agreement with one another, have an end face 22 or 24 parallel to the base plane 12.
• the length of each of the end faces 22 and 24 is approximately 45 ° of the length of the diametral web 14.
• Radially outward, the two webs 16 and 18 of the cross-shaped elevation 20 according to FIGS. 4 to 6 are delimited by inclined surfaces which are directed against the axis are inclined at an angle of 22 °.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Details Of Spanners, Wrenches, And Screw Drivers And Accessories (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6399812

Family Applications (1)

Country Status (2)

Cited By (2)

Families Citing this family (4)

Citations (3)

Family Cites Families (1)

• 1990
  • 1990-02-09 DE DE19904004007 patent/DE4004007C1/de not_active Expired - Lifetime
• 1991
  • 1991-02-08 WO PCT/EP1991/000250 patent/WO1991012115A1/de not_active Ceased

Patent Citations (3)

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