FR2620639A1 - Improvement to machines for manufacturing netting - Google Patents

Abstract

The invention relates to a device for a machine for manufacturing so-called "single twist" netting with metal wire, of the type comprising a stationary die in the bore of which rotates a steel strip driving the metal wire which is wound on it, thereby adopting the shape of a coil spring, the turns of which are flattened so that they interlock, by screwing, with those of the previously shaped wire. It is characterised in that the flat strip is replaced by a twisted strip 7 causing an additional twist of the turns and allowing them to return at the rear by means of the spring effect so that all the said turns are perfectly flat at the die exit. The leading twisted strip 7 comprises a first helical portion 8, 9 preceding a second helical portion 11, 12, between which portions there is a non-twisted part 10.

Description

Improvement to wire mesh machines.

 The present invention relates to machines for making the mesh called "simple twist" with metal wire.

 In known machines, the traditional device for making the turns of the wire constituting the mesh known as "simple twist", consists of a flat blade rotating in the bore of a fixed die and driving in its rotation the metal wire which is there rolls up in the form of a coil spring whose turns are flattened, so that at the outlet of the die the wire thus shaped is interlocked by screwing into the turns of the strand previously obtained.

 If this device is well suited for making the turns of a mild steel wire annealed because it does not react after conformation, the same does not apply to a wire made of stainless steel, or of slightly tempered hardened steel, or in hardened aluminum, or in bronze or brass for example, which reacts at the exit of the die by a backward movement of a half-turn of the turns, after two to four turns of the blade depending on the reaction of the wire due to the relaxation of metal so that, all of said turns not being perfectly flat, the manufacture of "single twist" mesh cannot be achieved.

 To remedy this drawback, we imagine, according to the invention, a simple, practical and rational device which essentially consists in replacing the flat blade for driving the wire with a blade twisted in advance, causing an imposed twist of the turns and allowing their backward movement by the spring effect so that at the end of the die all the turns appear perfectly flat.

 According to a characteristic of the invention, this twisted blade comprises a first helical part directed in one direction, for example to the right, and a second helical part extending the previous one, directed in the other direction, for example to the left, while between these two parts is provided with a flat, non-twisted part.

 The invention is set out below in more detail with the aid of drawings representing only one embodiment.

 Figure 1 shows a traditional device for forming the turns. of a mesh called "simple twist".

 Figure 2 shows the new wire winding and shaping blade according to the invention.

 Figure 3 is a side view.

 In FIG. 1, the reference 1 designates, in a known machine for making the mesh known as "simple twist", the fixed die comprising a helical groove 2 which causes the turns to advance and determines the pitch while the metallic wire 3 wraps around the flat steel blade 4 which rotates in the bore of said die 1 and whose end 5 is clamped in a mandrel rotated by an electric motor, elements not shown.

 By turning, the blade 4 causes the winding of the metal wire 3, generally an annealed mild steel wire which takes the form which is imposed on it without reaction, that is to say the form of a coil spring whose turns 6 are flattened.

 To allow the manufacture of a so-called "simple twist" wire mesh of stainless steel wire, or of slightly tempered steel, or of hardened aluminum, or of bronze, or of brass, or of mild steel wire, especially galvanized nut , it has been imagined, according to the invention, to replace the flat blade 4, a blade 7 twisted in advance as shown in FIGS. 2 and 3.

 This twisted blade 7 has a first helical part, the length of which, between the marks 8 and 9, is at least equal to one and a half steps of the turns 6. Then the twisted blade 7 is extended by a flat part 10 of a half -not, then continues with a second helical part, between the marks 71 and 12, of length equal to the previous one, but directed in the opposite direction, that is to say for example, that the first twist twists to the right and the second, after the flat part, twists to the left. It goes without saying that a twist to the left, then to the right is also adaptable.

 The twisted blade portion 7 between the marks 8 and 9, for the purpose of twisting, beyond what is necessary, the wire 3 so that the spring effect tends to bring it back what allows obtain the second blade portion located between the marks 11 and 12, so that the set of turns leaves the die 1 perfectly flat.

 As for the flat part 10 located between the two twisted portions of the blade 7, it allows the folding of a turn to take place while the previous part follows this part. Furthermore, it reduces the friction of the blade 7 during its rotation in the bore of the die 1 because it is guided over a larger segment.

 This device can be easily adapted on all machines for making the mesh called "simple twist". I1 also allows the use of plasticized wire whose annealed mild steel core can be of a larger diameter than traditionally.

 This device makes it possible to manufacture so-called "simple twist" wire mesh, with stainless steel wire, which appreciably increases the duration of the wire mesh and increases its resistance to impacts and to cutting, without increasing the cost price.

 In addition, this device makes it possible to manufacture so-called "simple twist" wire mesh on a semi-automatic machine using wires cut in advance or recovery wires, for example.

Claims (7)

Claims  1 - Device for a machine for making the mesh known as "simple twist" with metallic wire, of the kind comprising a fixed die (1) in the bore of which rotates a steel blade (4) driving the metallic wire (3) which is wound up there by taking the form of a coil spring whose turns (6) are flattened so that they nest by screwing in those of the previously shaped wire, characterized in that the traditional flat blade (4) is replaced by a twisted blade (7) capable of causing additional twisting of the turns (6) and of authorizing their return to the quarry by the spring effect so that the assembly of said turns is perfectly flat at the outlet of the wire (1).  2 - Device according to claim 1, characterized in that the advance twisted blade (7) comprises a first helical portion (8,9) preceding a second helical portion (11,12) between which is provided a non-twisted part (10).  3 - Device according to claim 2, characterized in that the helical parts (8,9,11,12) of the blade (7) are twisted in opposite directions, that is to say one to the right and the other on the left, or vice versa.  4 - Device according to claim 2, characterized in that the helical portions (8,9,11,12) of the blade (7) measure a pitch and a half of the turns (6) of the wire (3).  5 - Device according to claim 2, characterized in that the flat portion (10) of the blade (7) measures a half-step of the turns (6) of the wire (3).  6 - Machine for making the mesh called "simple twist" using a device according to claims 1 to 5, for conforming the wire of stainless steel, hardened tempered steel, hardened aluminum, bronze, brass, mild steel work hardened, for example, but not exclusively, bare or plasticized.  7 - Semi-automatic machine for making the mesh called "simple torsion'1 equipped with a device according to claims 1 to 5, allowing the use of pre-cut son or recovery son.