MACHINE FOR FORMING METAL PINS AND RELATED FORMING PROCESS

Abstract

 The invention relates to a solution that would allow metal wires to be machined by making a plurality of pins of any cross section while maintaining in a fixed, i.e., non-rotary configuration, the coining punches - thus reducing their number - and at the same time ensuring precise and reliable sharpening with a simple movement of the wire around its axis according to limited rotations at predefined angles. The metal wire to be machined is then made to move forward and rotated inside a forming machine where a first coining of the wire is carried out, again with the same tools, a first partial rotation of the wire, a second coining at the same point and a second partial rotation in order to weaken the coining point so that the ending stretch of the wire separates to make a sharpened metal pin.

Description

Technical Field

[0001] The present invention relates to a machine for forming metal pins and related forming process, particularly for making sharpened pins of round, square and/or rectangular cross section.

Background Art

[0002] Pins of this type are made by coining from a single metal wire and generally mounted in electrical connectors intended to be soldered to printed circuit boards by means of such pins. Pins may have straight or folded extensions and usually comprise two tapered mating end portions, one which can be inserted into the opening or hole cut into the printed circuit board (and which will then be soldered to the circuit board) and an opposite one which serves as a de facto male for mechanical coupling to the various internal elements of the connector with the function of electrical transmission of signals.

[0003] In the remainder of this description and in the subsequent claims, the term "sharpened" will refer to the shape of the end portions of the pins which, by appropriate machining, are pointed/tapered to facilitate couplings with the electronic devices to which they are applied; these ends terminate, in the case of wires of square or rectangular cross section, in the shape of a truncated pyramid or, in the case of wires of round cross section, in the shape of a truncated cone. Subsequent uses of similar terminology such as chamfering, tapering, pointing, etc., should be interpreted in the sense defined above.

[0004] In accordance with common techniques known in the metal smallware industry, sharpening is done by means of cold processes in which the ends can be machined by material removal (e.g., turning) or by mechanical deformation without material removal (e.g., hammering/coning) through specific automatic machines.

[0005] In the case of machining without material removal, matrix hammering machines are generally used rotating around the wire and supporting coining punches movable in a radial manner to operate on the ends of the pins to form the sharpened ends. The matrices are usually composed of multiple punch holder segments that, depending on the application and on the tip conformation, can be made into subdivisions of up to eight segments. Rotary hammering machines are in fact high-speed presses the punches of which have a controlled travel obtained by means of cam drives moved by the relevant rotation of one or more rotors connected to motor means.

[0006] As can be guessed, machines of this type are very expensive and complicated to manufacture and, given the many kinematics involved, they require constant lubrication with frequent maintenance.

Description of the Invention

[0007] The Applicant, faced with the aforementioned problems, has devised a solution that would allow metal wires to be machined by making a plurality of pins of any cross section while maintaining in a fixed, i.e., non-rotary configuration, the coining punches - thus reducing their number - and at the same time ensuring precise and reliable sharpening with a simple movement of the wire around its axis according to limited rotations at predefined angles. The metal wire to be machined is then made to move forward and rotated inside a forming machine where a first coining of the wire is carried out, again with the same tools, a first partial rotation of the wire, a second coining at the same point and a second partial rotation in order to weaken the coining point so that the ending stretch of the wire separates to make a sharpened metal pin.

[0008] In this context, the Applicant has thus developed a machine and the relevant forming process that is easy to manufacture, affordable and adaptable to different configurations that enables the manufacture of sharpened metal pins preferably insertable into connectors for electrical/electronic applications.

[0009] In view of the above, the present invention therefore relates, in its first aspect, to a machine for forming metal pins having the characteristics of claim 1. According to a further aspect, the present invention relates to a process for forming metal pins having the characteristics of claim 6.

Brief Description of the Drawings

[0010] Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a machine for forming metal pins and the related process, illustrated by way of an indicative yet non-limiting example in the accompanying tables of drawings in which:

• Figure 1 is a schematic side view of a machine for forming sharpened metal pins according to the invention,
• Figures 2-8 are perspective views of the phases of the process for forming sharpened metal pins according to the invention,
• Figure 9 is a front view of the rotational block of the wire which is part of the rotational block,
• Figures 10 and 11 are a top and a front view, respectively, of the intermediate gear which can be coupled to the rotational block,
• Figure 12 is a cross sectional view of the rotational sleeve which can be fitted into the intermediate gear, and
• Figure 13 is a front view of the twist sleeve which is part of the rupture block.

Embodiments of the Invention

[0011] With particular reference to these figures, reference numeral 1 globally denotes a machine, preferably automatic, for forming sharpened metal pins in accordance with the present invention.

[0012] The machine 1 comprises a general framework 2 supporting a feeding station 3 of a metal wire 50, a coining station 4 from which to get a plurality of metal pins 60 with sharpened ends 61, 62, and an outlet station 5 for the exit of the pins 60.

[0013] In one of the preferred embodiments, the feeding station 3 is provided with a feeding coil 6 supported in a rotating manner by a shaft 7, preferably idle, on which is wound the metal wire 50 intended to be transferred, preferably unwound intermittently (or step-by-step), towards the coining station 4 along a substantially straight way of forward movement A with a longitudinal direction X-X, from the feeding station 3 towards the outlet station 5.

[0014] As will be seen below, at the beginning of the process, the free end of the wire 50 is made to pass through the coining station 4 to be temporarily blocked in the outlet station 5 during the machining of the wire 50. Such machining allows for a plurality of metal pins 60 to be made with a round, square and/or rectangular cross section in which the ends 61, 62 are sharpened according to predetermined angles depending on the intended use of the pin 60. According to the innovative process which will be explained in detail later in this description, the pins 60 are made by repeatedly coining the wire 50 at a coining point 56 so that, at the end of the machining, an ending stretch 52 is separated from an initial stretch 51 of the wire 50 to form the pins 60. Advantageously, the sharpening of the ends 61, 62 of the pin 60 is made by appropriately coining the wire 50 without rotary movements by the tools.

[0015] In the remainder of this description and in the subsequent claims, the terms "stretch" or "pin" may denote the same portion of wire that will be either still attached to the metal wire (stretch) or separated from the wire (pin), respectively, depending on the phase in the process. As shown in the example in Figure 3, the wire 50 has therefore an ending stretch 52 and an initial stretch 51 divided by the coining point 56, which turns out to be the point where the separation between the two stretches 51, 52 occurs. Once the ending stretch 52 is detached from the wire 50, for each pin 60 made, two sharpened ends 61, 62 are then identified: truncated pyramid-shaped in the case of wires with square or rectangular cross sections, or truncated cone-shaped in the case of wires with round cross sections.

[0016] For sake of exposition, the following description will refer to the machining of a metal wire specifically with a square cross section. The machinery and process of the invention are, of course, not limited to this embodiment; in the case, in fact, of machining metal wire with rectangular or circular cross section, the machinery and related process can be adapted with minimal modifications that will be specified in detail below without limitation on the scope of protection as claimed.

[0017] As shown in the example of Figure 1, the feeding station 3 comprises a feeding block 8 configured to make the metal wire 50 move forward along the way of forward movement A towards the outlet station 5 according to techniques known in themselves. For example, the feeding block 8 may comprise a gripper 9 movable along a forward-moving guide 10 between a first grasping position, wherein the gripper 9 grasps the wire 50 in a backward position to drag it step-by-step towards the outlet station 5, and a release position, wherein the gripper 9 releases the wire 50 to return to the grasping position and grasp it again in a new backward position. It cannot, however, be ruled out that the feeding block 8 may have different conformation for moving the wire 50 forward by using different feeding means dedicated to the same purpose.

[0018] In more detail, as will better described below, the coining station 4 mainly comprises:

• a rotational block 11 of the metal wire 50, and
• a coining block 12 for the formation of the sharpened ends X, X and
• a stapling block 13 (optional) for the formation of at least one seat intended to receive, by shape coupling, retaining means provided in the connectors so as to block the pin into the connector.

[0019] As shown in Figures 1 and 9, the rotational block 11 comprises a supporting plate 14 which is developed mainly transversely with respect to the longitudinal direction X-X of forward movement of the wire 50, which plate is drilled centrally to form an opening 16 to receive a twist sleeve 17 (Figure 12) intended for the rotation of the metal wire 50. Preferably, the upper portion 15 of the plate 14 is drilled transversely (along the direction Z-Z) to accommodate a securing screw 19 and comprises a vertical connecting groove 20 with the opening 16 to form two jaws 21, 22 which, depending on the tightening of the securing screw 19, allows the jaws 21, 22 to be moved close to/away from each other.

[0020] The twist sleeve 17 is pivoted in an intermediate gear 23 (Figure 10 and 11) which serves as a cylindrical sleeve holder fitted in the opening 16 between the jaws 21, 22. The intermediate gear 23 has a longitudinal opening 24 with a square cross section to receive, by shape coupling, the sleeve 17.

[0021] The twist sleeve 17 preferably has a square outer cross section and is provided with a through opening 18 cut longitudinally also with a square cross section for the passage of the metal wire 50.

[0022] In the case of machining metal wires 50 with a rectangular cross section, it will be sufficient to use a different twist sleeve 17 of complementary cross section and mount it in the intermediate gear 23 as described above.

[0023] As can be seen in the example in Figure 12, the through opening 18 of the twist sleeve has a larger cross section where the inlet portion 18a of the wire 50 is located and a cross section of substantially the same size as that of the wire 50 where the outlet portion 18b of the wire 50 is located. Thus, when machining the metal wires 50 of square or rectangular cross section, the rotation of the sleeve 17 allows the rotation of the wire 50 thanks to the shape coupling between the opening 18 and the outer surface of the wire 50.

[0024] The intermediate gear 23 has a mainly longitudinal development and is shaped so that it comprises two main portions 25, 26 wherein the proximal portion 25 has a diameter substantially corresponding to the diameter of the opening 16 of the plate 14, while the distal portion 26 is of smaller diameter and serves as a seat for a pinion 27 (Figure 1) intended to couple with a crown gear 28 (or similar rack means) located below, the latter being connected to a motorized drive (not shown) to give the rotary motion, explained in detail later in this description, to the sleeve 17. The rotation of the intermediate gear 23 then gives the rotation to the sleeve, which in turn gives the rotation to the wire 50, particularly to the initial stretch 51. As shown in Figures 10 and 11, the sleeve 17 is clamped to the intermediate gear 23 by means of a securing pin 29 which can be fitted into a transverse hole 30 formed through the proximal portion 25 of the gear 23.

[0025] In accordance with one embodiment, in the case of machining metal wires 50 with a round cross section, the rotational block 11 may comprise, instead of the twist sleeve 17, a rotary gripper (not shown) provided with at least two branches, each of which has an inner surface with a circular cross section having a shape complementary to the outer surface of the circular wire to be grasped. The branches are movable towards each other to tighten the wire 50 and, once tightened, the rotary gripper is rotated by means of a pinion-rack system, the operation of which is entirely similar to that described with reference to the twist sleeve 17. Different gripping and rotational systems cannot however be ruled out, e.g. provided with grippers that can be completely rotated on guides by motor means according to techniques known in themselves.

[0026] Downstream of the rotational block 11 is the coining block 12 for shaping the sharpened ends 61, 62 of the pins 60 which block comprises two coining punches 31 positioned on opposite sides with respect to the wire 50. Each punch 31 is supported by respective slides 32 movable by means of typical pneumatic drives (e.g., cam, not shown) towards each other vertically along the direction Y-Y. In use, each punch 31 is therefore movable along the vertical direction Y-Y transverse to the direction X -X of forward movement of the wire 50 towards the latter.

[0027] In accordance with one embodiment, the punches 31 end with an angular tip 33 the shape of which is selected depending on the sharpening angle. For example, as shown in the example in Figure 3, the tip 33 may have an isosceles shape wherein the two sides 34, 35 facing the wire 50 have corresponding angles of inclination, e.g., equal to 70° with respect to the vertical. However, punches 31 can be selected wherein the two sides 34, 35 of the tip 33 have different inclinations, in order to make pins 60 with differently sharpened ends 61, 62. The punches 31 substantially reproduce in negative at least partly the geometry of the sharpened ends 61, 62 by means of a movement of the punches 31 towards the wire 50 between a home position, wherein the punches 31 are moved away from the wire 50, and a penetration position wherein the tips 33 of the punches 31 partly penetrate into the wire 50 so as to change the surface thereof and to make "V"-shaped grooves/slots having a predetermined depth which is adapted to reduce the diameter/section of the wire by a value of between 20% and 70%, preferably by 50%.

[0028] As will be seen below, the coining and thus the penetration of the tips 33 on the wire 50 is done first on the upper faces 53 and lower faces 54 of the wire 50 and then, after rotation, on the side faces 55. Optionally, an additional coining or multiple coining may be done on the wire on the upper faces 53 and lower faces 54 or on the side faces 55 depending on how the wire 50 is rotated by the rotational block 11.

[0029] As illustrated in the example in Figure 1 and Figures 2-9, the (optional) stapling block 13 is configured to form at least one seat in the pins 60 which is intended to receive, by shape coupling, retaining means provided in the connectors in such a way that the pin 60 is clamped when inserted into the connector.

[0030] The stapling block 13 is entirely similar to the coining block 12 and comprises two wedges 36 positioned on opposite sides with respect to the wire 50. Each wedge 36 is supported by respective slides 37 movable by means of typical pneumatic drives (e.g., cam, not shown) vertically towards each other along the direction Y-Y. The travel of the slides 37 of the wedges 36 towards the wire 50 is selected to achieve an engraving preferably only in the upper faces 53 and lower faces 54.

[0031] The wedges 36 end, preferably, with a double angular tip 38 to reproduce in negative, at least partly, the geometry of the engravings. The use of different tips, e.g., single-pointed or otherwise, cannot however be ruled out to generally make seats intended for coupling with the relevant clamping means.

[0032] As shown in the example in Figure 1, the outlet station 5 is located downstream of the coining station 4 and is configured, as will be appreciated below, to temporarily hold the ending stretch 52 of the wire 50 before breaking/separating from the initial stretch 51 just adjacent thereto. The ending stretches 52, after being separated from the wire 50, substantially become the pins which are ejected from the machine 1 and collected by dropping into a receptacle for subsequent packaging.

[0033] For this purpose, the outlet station 5 comprises a breaking block 39 provided with a breaking sleeve 40 (Figure 13) quite similar to the twist sleeve 17 but pivoted in a fixed manner (i.e., without the possibility of rotation) within a specific housing provided in the breaking block 39.

[0034] The breaking sleeve 40 preferably has a square outer cross section and is provided with a through opening 41 cut longitudinally, also with a square cross section, for the passage of the metal wire 50. A through hole 42 cut laterally in the sleeve allows it to receive a tightening screw 43 for clamping the sleeve 40 on the block 39.

[0035] In accordance with one embodiment, in the case of machining with wires 50 with a circular cross section, the breaking block 39 may comprise, instead of a breaking sleeve 40, a holding gripper (not shown) configured to retain the ending stretch 52 of the wire 50 during coining. The holding gripper turns out to be quite similar to the rotary gripper and can be made with jaws or similar holding means for retaining the ending stretch 52. Once the ending stretch 52 is separated from the wire, the jaws separate to allow the ending stretch/pin 60 to be ejected from the outlet station 5.

[0036] By way of an example, the pins 60 made by the machine 1 in accordance with the invention have:

• a length comprised between 5 mm and 50 mm, preferably about 15 mm,
• a cross section comprised between 0.2 mm and 1 mm, preferably about 0.64 mm,
• a length of the sharpened ends comprised between 0.2 mm and 0.8 mm, preferably about 0.4 mm,
• a sharpening angle comprised between 10° and 50°, preferably 20° (with respect to the axial direction of the pin).

[0037] The process for forming sharpened metal pins 60 according to the invention first involves a phase wherein the wire 50 is preferably unwound from the coil 6 and the free end is made to pass through the feeding station 3 and the coining station 4 (Figure 2) so that the ending stretch 52 is then fitted into the breaking sleeve 40 of the outlet station 5. Usually, at the beginning of the process, this phase is done manually by an operator before the automatic machine is activated. The ending stretch 52 is then temporarily blocked in rotation.

[0038] Next, the machine 1 is activated and a first coining is carried out in the coining station 4 where the coining point 56 of the wire 50 is located, which point is placed at a predetermined distance from the free end of the ending stretch 52.

[0039] After the wire 50 is blocked, a first coining is carried out wherein the coining punches 31 are moved towards each other along the vertical direction Y-Y and towards the coining point 56 so that the tips X partly penetrate the upper faces 53 and lower faces 54 of the wire 50. Once the punches 31 are moved away from the wire (Figure 3), the initial stretch 51 is rotated, preferably by 90° clockwise before a second coining is carried out.

[0040] Since the first coining shapes only the upper faces 53 and the lower faces 54 of the wire 50 in a V pattern (where the coining point 56 is located), in order to form satisfactorily sharpened ends, it is necessary to sharpen the side faces 55 of the wire 50 as well. To this end, the wire 50 - particularly the initial stretch 51 - is then rotated (Figure 4) to expose the side faces 55 towards the punches 31 for the second coining, specifically by making a rotation of about 90°.

[0041] In the second coining (Figure 5), the coining punches 31 are moved towards each other along the vertical direction Y-Y and towards the coining point 56 so that the tips 33 partly penetrate in the side faces 55 of the initial stretch 51 (and then the side faces 55 of the ending stretch 52, the latter being clamped in rotation).

[0042] The second coining then allows the side faces 55 of the wire 50 to also be shaped in a V pattern, thus making a pyramidal sharpening (which in the case of a wire with a circular cross section will result in a truncated cone shape). Two mirroring sharpened ends 61, 62 are substantially made where the coining point 56 is located, one on the initial stretch 51 and one on the ending stretch 52 of the wire 50, connected to each other by a small portion of material.

[0043] For the separation of these ends 61, 62, it is possible to proceed as follows: make a third rotation (Figure 6) preferably counterclockwise by 90° (but can also be made clockwise) to allow the breaking of the coining point 56 and thus the separation of the two ends 61, 62 of the stretches 51, 52. The third rotation also allows the upper faces 53 and the lower faces 54 of the stretches 51 and 52 to return aligned as in the first coining phase (Figure 3).

[0044] Preferably, a third coining (Figure 7), quite similar to the previous ones, can be carried out to make sure that the stretches 51, 52 are permanently separated.

[0045] Optionally, a stapling of the upper faces 53 and lower faces 54 of the initial stretch 51 can be carried out by means of the stapling block 13 placed upstream of the coining block 12. In detail, there is a phase wherein an engraving is made where the upper faces 53 and lower faces 54 are located at an engraving point 57 arranged upstream of the coining point 56. This phase is preferably carried out after the first or third coining.

[0046] Finally, the ejection of the pin 60 thus made (Figure 8) is carried out by pushing the latter by means of the feeding of the wire 50 in the way of forward movement A to start a new coining phase.

[0047] It has in practice been ascertained that the described invention achieves the intended objects, and in particular the fact is emphasized that by means of the present invention it is possible to make a continuous process which allows the forming of enormous amounts of sharpened metal pins, even 9000 pins per hour and more, depending on the complexity of the smallware to be made, by means of a precise and reliable machine and process with a simple movement of the wire around its axis according to limited rotations at predefined angles. Obviously, a branch engineer, in order to meet contingent and specific needs, may make numerous modifications and variations to the system and method described above, all of which, however, are contained within the scope of protection of the invention as defined by the following claims.

Claims

1. Machine (1) for forming metal pins (60) comprising:

- a feeding station (3) of a metal wire (50), preferably wound in a coil (6),

- an outlet station (5) located downstream of said feeding station (3) for the outlet of sharpened metal pins (60) comprising:
a breaking block (39) configured to receive an ending stretch (52) of said metal wire (50) in order to temporarily prevent it from rotating and to separate an initial stretch (51) of the wire (50) from said ending stretch (52),

- a coining station (4) located between said feeding station (3) and said outlet station (5) and comprising

a coining block (12) configured to make an initial coining at a coining point (56) of the wire (50) located at a predetermined distance from said ending stretch (52) and wherein said coining point (56) is coined at an upper face (53) and/or lower face (54) of said wire (50),

a rotational block (11) located upstream of said coining block (12) and configured to make a first partial rotation of the initial stretch (51) of wire (50),

wherein
said coining block (12) is also configured to make a second coining at said coining point (56) at least in one of the side faces (55) of said wire (50),
and wherein
said rotational block (11) is configured to make a second partial rotation of said initial stretch (51) of wire (50) subsequently to said second coining in order to weaken said coining point (56) so that said ending stretch (52) separates from said initial stretch (51) to make a sharpened metal pin (60).

2. Machine (1) according to the preceding claim, wherein said coining block (12) is configured to make a third coining at said coining point (56) to shape again said wire (50) in a V pattern at least at the point where said upper face (53) and/or lower face (54) is located.

3. Machine (1) according to the preceding claim, wherein said coining station (4) comprises a stapling block (13) located between said rotational block (11) and said coining block (12) and configured to make at least one engraving at an engraving point (57) of said initial stretch (51) upstream of said ending stretch (52) and thereafter said first and/or said third coining at the point where said upper face (53) and/or lower face (54) is located.

4. Machine (1) according to any one of the preceding claims, wherein said feeding station (3) comprises a feeding block (8) configured to move said metal wire (50) forward along a direction of forward movement (A) intermittently towards said outlet station (5) so that said sharpened metal pin (60) is pushed from said initial section (51) of wire (50) to exit said machine (1).

5. Machine (1) according to any one of the preceding claims, wherein said coining block (12) comprises at least one coining punch (31) movable towards said wire (50) intended to penetrate at least partly into said wire (50) so as to make "V"-shaped grooves/channels having a predetermined depth.

6. Process for forming metal pins (60) comprising the phases of:

- receiving from a feeding station (3) metal wire (50) preferably unwound from a coil (6),

- making said wire (50) pass through a coining station (4) located downstream of said feeding station (3),

- temporarily blocking an ending stretch (52) of said wire (50) at an outlet station (5) located downstream of said feeding station (3) in order to prevent said ending stretch (52) from rotating, and at the end of the process the latter be separated from an initial stretch (51) of said wire (50) to form sharpened metal pins (60),

wherein in said coining station (4) the following phases are provided:

- making an initial coining at a coining point (56) of wire (50) located at a predetermined distance of said ending stretch (52) at least at the point where an upper face (53) and/or lower face (54) of said wire (50) is located,

- making a first partial rotation of said initial stretch (51) subsequently to said first coining, at an initial stretch (51) of said wire (50) located upstream of said ending stretch (52),

- making a second coining at said same coining point (56) at least in one of the side faces (55) of said wire (50),

- making a second partial rotation of said initial stretch (51) of wire (50), subsequently to said second coining, in order to weaken said coining point (56) so that said ending stretch (52) separates from said initial stretch (51) to thus make a sharpened metal pin (60).

7. Process according to the preceding claim, comprising the phase of making a third coining at said same coining point (56) to coin again said wire (50) at the point where said upper face (53) and/or lower face (54) is located.

8. Process according to claim 6 or 7, comprising the phase of making at least one engraving at an engraving point (57) of said initial stretch (51) upstream of said ending stretch (52) and subsequently to said first and/or said third coining at the point where said upper face (53) and/or lower face (54) is located.

9. Process according to any one of claims 6-8, comprising the phase of making said metal wire (50) move forward along a direction of forward movement (A) intermittently towards said outlet station (5) so that said sharpened metal pin (60) is pushed by said initial stretch (51) of wire (50) out of said outlet station (5).

Drawing