Hand tool step drive mechanism and crimping method

A pair of crimping pliers (100) in order to crimp two parts together, characterized in that said pliers include, with reference to the normal position of use and to the direction of drive:

• a hollow body (101) which has a rear end (101a) and a front end (101b);
• a fixed handle (102) which is an integral part of the hollow body (101);
• a rack (103) which is mounted in the hollow body (101) so as to slide between a starting position (Pr) and a crimping position (PF) and which has:
• a first toothing (104) having rearwardly angled teeth (104a) which is arranged on an upper edge (103a);
• a second toothing (105) having rearwardly angled teeth (105a) which is arranged on a lower edge (103b);
• a front end (103c) which is provided with a punch (106);
• a handle (107), acting as a lever, which is mounted so as to pivot in the hollow body (101) between a maximum tightening position (PSM) and a stripping position (PDEV), said handle (107) comprising a hollow upper end (107a) which receives a torsion spring (108) which bears against said hollow upper end (107a) and bears against a drive ratchet (109), which is mounted so as to pivot in the hollow body (101), in front of the hollow upper end (107a), and is provided with a crossbar (109a) which engages between the teeth (104a) of the first toothing (104);
• a locking ratchet (110) which is mounted so as to pivot in the hollow body (101) and is provided with a crossbar (110a) which engages between the teeth (105a) of the second toothing (105), a compression spring (111) being arranged bearing against the locking ratchet (110) and bearing against a stop (103d) which is situated on a rear end (103e) of the rack (103).

A crimping method for crimping two parts together which includes:

• a) supplying the two parts;
• b) positioning the two parts in a crimping position;
• c) supplying a pair of crimping pliers, the pair of crimping pliers further comprising, with reference to the normal position of use and to the direction of drive:
• a hollow body (101) which has a rear end (101a) and a front end (101b);
• a fixed handle (102) which is an integral part of the hollow body (101);
• a rack (103) which is mounted in the hollow body (101) so as to slide between a starting position (Pi) and a crimping position (PF) and which has:
• a first toothing (104) having rearwardly angled teeth (104a) which is arranged on an upper edge (103a);
• a second toothing (105) having rearwardly angled teeth (105a) which is arranged on a lower edge (103b);
• a front end (103c) which is provided with a punch (106);
• a handle (107), acting as a lever, which is mounted so as to pivot in the hollow body (101) between a maximum tightening position (PSM) and a stripping position (PDEV) said handle (107) comprising a hollow upper end (107a) which receives a torsion spring (108) which bears against said hollow upper end (107a) and bears against a drive ratchet (109), which is mounted so as to pivot in the hollow body (101), in front of the hollow upper end (107a), and is provided with a crossbar (109a) which engages between the teeth (104a) of the first toothing (104);
• a locking ratchet (110) which is mounted so as to pivot in the hollow body (101) and is provided with a crossbar (110a) which engages between the teeth (105a) of the second toothing (105), a compression spring (111) being arranged bearing against the locking ratchet (110) and bearing against a stop (103d) which is situated on a rear end (103e) of the rack (103);
• d) positioning the front end of the hollow body behind the parts with reference to the direction of drive of the rack, said rack being in a starting position (Pi);
• e) step driving the rack toward the two parts by successively tightening the handle toward the fixed handle, at a tightening force which is less than a tightening force necessary for the punch to pierce the parts, until the punch is in a contact position (PC) with a first of the two parts;
• f) applying a tightening force sufficient to pierce the two parts with the punch;
• g) step driving the rack through the two parts as a result of successively tightening the pivotable handle toward the fixed handle, at a tightening force which is less than a tightening force necessary for the punch to pierce the parts, until the crimping of the two parts is obtained.