Punch for crimping tool and crimping tool provided with such a punch

Abstract

The present invention proposes a crimping punch making it possible to obtain a crimping that is resistant to pulling out. To this end, the punch (20) for a crimping tool comprises a fixing part (21) for fixing to the tool and a punching part (22) consisting of a spike (23) connected to the fixing part by two crimping faces (24) that each exhibit a rectilinear primary profile (241), each crimping face also comprising a secondary profile (242), provided with four notches (243) having a radius of between 1 mm and 2.5 mm, preferably between 1.2 mm and 2 mm, advantageously 1.5 mm.

Claims

1. A punch (20) for a crimping tool, comprising a part (21) for fixing to the tool and a punching part (22) consisting of a spike (23) connected to the fixing part by two crimping faces (24) each having a primary rectilinear profile (241), each crimping face furthermore comprising a secondary profile (242) provided with four notches (243) having a radius of between 1 mm and 2.5 mm.

2. The punch as claimed in claim 1, wherein the notches (243) in each crimping face have a same radius.

3. The punch as claimed in claim 1, wherein the notches (243) in each crimping face have different radii.

4. The punch as claimed in claim 1, wherein each notch has a depth (P), taken between the primary profile (241) and a point of the notch furthest from the primary profile, the depth being between 0.15 mm and 0.33 mm.

5. The punch as claimed in claim 4, wherein the notches (243) in each crimping face have a same depth.

6. The punch as claimed in claim 4, wherein the notches (243) in each crimping face have different depths.

7. The punch as claimed in claim 1, wherein the punching part (22) has a height (H.sub.22) of between 0.9 cm and 1.5 cm and a width (L.sub.22) of between 0.7 cm and 0.9 cm.

8. The punch as claimed in claim 1, wherein the radius is between 1.2 mm and 2 mm.

9. The punch as claimed in claim 8, wherein the radius is 1.5 mm.

10. A crimping tool for crimping two pieces together, comprising two jaws mounted in translation relative to one another, between an open position in order to be positioned on either side of the pieces to be crimped and a closed position at the end of crimping, characterized in that one of the jaws carries a punch as claimed in claim 1 and the other jaw has a die for receiving the punch when the two jaws are in the closed position.

11. The punch as claimed in claim 10, wherein the height (H.sub.22) is between 1 cm.

12. The punch as claimed in claim 10, wherein the width (L.sub.22) is 0.83 cm.

13. A crimping tool for crimping two pieces together, comprising a first and a second jaw spaced apart and mounted fixedly relative to one another, characterized in that the first jaw carries a punch as claimed in claim 1 mounted movably in translation between an open position in which the punch is retracted into the first jaw in order to allow the positioning of the jaws on either side of the pieces to be crimped and a crimping position in which the punch extends from the first jaw as far as the second jaw, the second jaw having a die for receiving the punch when the punch is in the crimping position.

14. A crimping tool for crimping two pieces together, comprising two jaws mounted pivotably and in translation relative to one another between an open position in order to be positioned on either side of the pieces to be crimped and a closed position, characterized in that one of the jaws carries a punch as claimed in claim 1 mounted movably in translation between a cleared position in which the punch is retracted into the first jaw and a crimping position in which the punch extends from the first jaw as far as the second jaw, and the second jaw has a die for receiving the punch when the two jaws are in the closed position.

Description

(1) Further features of the invention will be described in the following detailed description given with reference to the appended drawings, which show, respectively:

(2) FIG. 1: a schematic plan view of a prior art punch;

(3) FIG. 2: a schematic plan view of a first embodiment of a punch according to the invention;

(4) FIG. 3: a schematic plan view of a second embodiment of a punch according to the invention, with manufacturing settings;

(5) FIG. 4: a photograph of prior art crimping pliers provided with a punch according to the invention;

(6) FIGS. 5 and 6: photographs, respectively, front-on and in profile, of an assembly for measuring the resistance to pulling-out of crimpings achieved using a punch according to the invention; and

(7) FIG. 7: a front-on photograph of an assembly for measuring the force required for crimping implemented with the aid of a punch according to the invention.

(8) As FIG. 1 shows, a prior art punch 10 comprises a part 1 for fixing to a crimping tool (not shown) and a punching part 2 consisting of a spike 3 connected to the fixing part 1 by two crimping faces 4 having a primary rectilinear profile and a secondary smooth profile.

(9) FIG. 2 illustrates a first embodiment of a punch according to the invention. This punch 20 comprises a part 21 for fixing to a crimping tool and a punching part 22 consisting of a spike 23 connected to the fixing part 21 by two crimping faces 24.

(10) According to the invention, each crimping face 24 comprises a primary rectilinear profile 241 and a secondary toothed profile 242. More particularly, the secondary profile comprises four notches 243 defining three teeth 244 between them.

(11) The transition from zero teeth to one tooth and from one tooth to two teeth per crimping face considerably increases the crimping force necessary.

(12) It was found, surprisingly, that the number of three teeth separated by four notches of a radius between 1 mm and 2.5 mm made it possible to increase the resistance to a pulling-out of the crimping while limiting the mean force necessary for crimping.

(13) With a radius of 2.5 mm, the mean crimping force increases by barely 7% as compared to a smooth punch, whereas crimping resistance increases by almost 32%.

(14) Preferably, the radius of the notches is between 1.2 mm and 2 mm.

(15) With a radius of 2.5 mm, the mean crimping force increases by barely 7% as compared to a smooth punch, whereas the crimping resistance increases by almost 132%.

(16) Advantageously, the radius of the notches is between 1 mm and 1.5 mm.

(17) Within this range, the mean crimping force is substantially identical to that of a smooth punch, while crimping resistance increases by almost 140%.

(18) All the notches in the same crimping face may have the same radius. Preferably, the notches in the same crimping face have different radii, it being understood that these radii are within the range of 1 mm to 2.5 mm, preferably 1.2 mm to 2 mm, advantageously 1.5 mm.

(19) The preferred embodiment is a punch comprising, on each crimping face, a first notch of 1 mm radius (first notch 243a, starting from the spike) and three notches of 2 mm radius (last three notches 243b, 243c, and 243d). This punch architecture is particularly effective since such a punch has a mean force necessary for crimping that is slightly (1.6%) less than that of a smooth prior art punch and a pulling-out resistance of 49 DaN, which is more than 150% greater than that obtained with a smooth prior art punch (19.8 DaN).

(20) Likewise, all the notches 243 in the same crimping face may either have the same depth or have different depths.

(21) The depth P is the distance taken between the primary profile 241 and the point of the notch furthest from the primary profile.

(22) Preferably, the depth of the notches of the punch according to the invention is between 0.15 mm and 0.33 mm.

(23) For example, the punch illustrated in FIG. 3 has notches of different depths. The first notch 243a, starting from the spike 23, has a depth P1 of 0.176 mm, while the last three notches 243b, 243c, and 243d, starting from the spike 23 have a depth P3 of 0.318 mm.

(24) The first notch 243a starting from the spike 23 is advantageously placed on each face 24 such that the spike 23 has a maximum width L.sub.23, taken between the primary profile and the junction with the first two notches, and is between 2.4 and 2.6 mm.

(25) For example, the punch illustrated in FIG. 3 has a spike width L.sub.23 of 2.55 mm.

(26) In the embodiment illustrated, the punching part 22 has a height H.sub.22 of between 0.9 cm and 1.5.

(27) For example, the punch illustrated in FIG. 3 has a height H.sub.22 of 1 cm approximately.

(28) The punching part 22 likewise has a width L.sub.22, taken at the level of the junction between the punching part and the fixing part, of between 0.7 cm and 0.9 cm.

(29) For example, the punch illustrated in FIG. 3 has a width L.sub.22 equal to 8.31 mm approximately.

(30) In the embodiments illustrated, machining has removed the material from the punch such that the apexes of the teeth of the faces 24 are tangential to the virtual rectilinear planes constituted by the primary profiles 241 of the faces 24.

(31) Material is removed in such a manner as to begin cutting the crimping faces in accordance with the concave slots 243 of specific radius of concavity.

(32) According to the invention, a bit of a radius between 1 mm and 2.5 mm, preferably between 1.2 mm and 2 mm, advantageously 1.5 mm, is used to remove the material from the punch.

(33) This removal of material is effected in such a manner that the spike of the teeth is slightly curved in order to allow the rolling of the material during crimping. If the spike of the teeth is too sharp, i.e. If the spike of each tooth is too pointed, there is a risk of cutting away material during crimping, thereby weakening the resistance to pulling-out of the crimping.

(34) Alternately, in embodiments that are not illustrated, the virtual straight planes of the faces 24 intersect the teeth of the crimping faces. The height of the teeth of each crimping face may thus be modulated while preserving a general straight form of said virtual faces 24.

(35) In the two embodiments of FIGS. 2 and 3, the spike 23 is centered relative to the first and second crimping faces. In other words, the longitudinal axis XX of the punch passing through the spike 23 is located at an equal distance d from the crimping faces at the level of the junction between the crimping part 22 and the fixing part 21.

(36) The fixing part 21 comprises two orifices: an oblong orifice 211 for guidance in translation and a circular, fixing orifice 212 for the passage of a screw for fixing to the mechanism for moving the crimping tool in translation.

(37) Such a crimping tool may, for example, be crimping pliers as described in patent FR2741830 and illustrated in FIG. 4.

(38) FIG. 4 illustrates a crimping tool 30 according to the invention for crimping two pieces together. This tool comprises two jaws M.sub.1 and M.sub.2 fixed relative to one another and spaced apart in order to be able to be positioned on either side of the pieces to be crimped.

(39) One M.sub.2 of the jaws carries a punch 20 according to the invention, mounted slidably in translation in the jaw M.sub.2 between an open position in which the punch is retracted into the first jaw and a crimping position in which the punch extends from the first jaw as far as the second jaw. The second jaw M.sub.1 has a die 31 for receiving the punch when the punch is in the crimping position.

(40) The punch is moved in translation by a knuckle mechanism (not visible in the figure) actuated by the relative movement of the handles 32 and 33 of the tool, in the direction of the arrow F1.

(41) A further subject of the invention is a crimping tool, which is not shown, comprising two jaws mounted pivotably and in translation relative to one another between an open position in order to be positioned on either side of the pieces to be crimped and a closed position in which one of the jaws carries a punch according to the invention, mounted movably in translation between a cleared position in which the punch is retracted into the first jaw and a crimping position in which the punch extends from the first jaw as far as the second jaw, and the second jaw has a die for receiving the punch when the two jaws are in the closed position.

(42) Such a tool is described in document FR2969951, except for the punch according to the invention.

(43) A further subject of the invention is a crimping tool, which is not shown, comprising two jaws mounted in translation relative to one another between an open position in order to be positioned on either side of the pieces to be crimped and a closed position at the end of crimping, in which one of the jaws carries a punch according to the invention and the other jaw has a die for receiving the punch when the two jaws are in the closed position.

(44) The six teeth of the punch according to the invention (three per crimping face 24) allow crimpings that are much more resistant to pulling-out to be obtained.

(45) Tests were performed with: E1: a punch with straight, smooth crimping faces, according to FIG. 1; E2: a punch with straight crimping faces, each provided with two teeth (three notches), produced using a bit of 2 mm radius; E3: a punch with straight crimping faces, each provided with two teeth (three notches), produced with a bit of 2.5 mm radius; E4: a punch with straight crimping faces, each provided with two teeth (three notches), produced with a bit of 3 mm radius; E5: a punch with straight crimping faces, each provided with three teeth (four notches), produced with a bit of 1 mm radius (for the first notch, starting from the spike) and a bit of 2 mm radius (for the last three notches); E6: a punch with straight crimping faces, each provided with three teeth (four notches), produced with a bit of 1.5 mm radius; E7: a punch with straight crimping faces, each provided with three teeth (four notches), produced with a bit of 2 mm radius; E8: a punch with straight crimping faces, each provided with three teeth (four notches), produced with a bit of 2.5 mm radius; E9: a punch with straight crimping faces, each provided with three teeth (four notches), produced with a bit of 3 mm radius.

(46) Thus, as illustrated in FIG. 5, crimping force measurements were performed with the punches E1 to E9 mounted on EDMA brand MASTER PROFIL model pliers 800 for carrying out a single crimping between two profiled STIL F530 brand rails R.sub.i and R.sub.s in 0.7 mm-thick galvanized steel marketed by PLACO SAINT GOBAIN. One 801 of the handles of the pliers 800 is immobilized in a vice 850 and the other handle 802 is pivoted in the direction of the arrow F1 by a bearing wheel 900 connected to a hydraulic jack (not shown) coupled to a SENSY brand, ref.: 2960-20KN-0.1, serial number 2120127000 force sensor (not shown) with a calibration certificate dated Jul. 9, 2013.

(47) The maximum force (in kilogram force) needed to perform the crimping between the two rails is measured over a jack travel Lv of 300 mm, between a position at 0 mm (shown in FIG. 13), in which the bearing wheel 900 is at a distance from the handle 802 of the pliers 800, and a position 300 mm, in which the handle 802 of the pliers 800 has been fully pivoted by the bearing wheel, corresponding to a maximum penetration of the punch into the rails (crimping position).

(48) Moreover, as illustrated in FIGS. 6 and 7, the pulling-out measurements performed on crimpings made using the punches E1 to E9 involved the assistance of a Kern brand, HCB model dynamometer 35 of version 3.1 dated July 2006.

(49) The experiments consisted in producing a single crimping between two 0.7 mm-thick STIL F530 brand galvanized steel profiled rails, marketed by PLACO SAINT GOBAIN, then in measuring the maximum force needed to achieve separation of the two rails, i.e. to pull apart the crimping, using the dynamometer 35.

(50) The assembly tested comprises a U-shape upper rail R.sub.s of 70 mm length, 48 mm width and 0.7 mm sheet thickness.

(51) The rail R.sub.s comprises lateral flanges 15 mm high, and lips facing toward the inside of the rail and parallel to the web of the U-shape rail measuring 5 mm. The lips hold the block connected to the dynamometer during measurement.

(52) The U-shape lower rail R.sub.i has a length of 110 mm, a width of 48 mm, a sheet thickness of 0.7 mm and flanges of height 15 mm.

(53) The upper R.sub.s and lower R.sub.i rails are crimped by a single crimping (reference 38 in FIG. 6) centered on the rails, i.e. in the center of the web of the U-shape profile section, equidistant from the flanges.

(54) These rails are conventionally used in the construction of plaster panel walls.

(55) The dynamometer is fixed to the upper rail R.sub.s by a fixing plate 36 immobilized under the lips of the rail, and the lower rail is immobilized on the support by two fixing pieces 37.

(56) The dynamometer is connected to a hydraulic arm (not shown) moving vertically and upward in order to pull apart the two rails.

(57) These tests yielded the following results:

(58) TABLE-US-00001 Mean force Number necessary for Force necessary for Number of Radius crimping pulling apart Test N.sup.o of teeth notches (in mm) (in DaN) (in DaN) E1 0 0 0 36.6 19.8 E2 2 3 2 41.5 41 E3 2 3 2.5 41.5 12 E4 2 3 3 41.5 17 E5 3 4 1&2 36 49 E6 3 4 1.5 36.6 46 E7 3 4 2 39 46 E8 3 4 2.5 39 26 E9 3 4 3 39 20

(59) These results confirm that a punch according to the Invention allows an increase in resistance to pulling-apart of between 30 and 150% as compared to a rectilinear, smooth punch, without thereby increasing the mean force necessary for crimping by more than 7%.

(60) With a punch according to E5, E6 or E7, two crimpings suffice to obtain resistance to pulling-out superior to that of a screw.

(61) It is thus possible very solidly to fix profiled sections together with few crimping operations, and without having recourse to screws, using a user-friendly tool that is not cumbersome and avoiding spoiling the insulating material slipped between the profiled sections.