ES2963456T3 - Pressure die for cold drawing and inserts for a pressure die - Google Patents

Abstract

A pressure die (1) comprising a die housing (10), a single pressure insert (30), a single extraction insert (40) and a locking ring (20) configured to lock the pressure insert ( 30 with respect to the die casing). (10), wherein said die housing (10) comprises a conical longitudinal through hole having a conical angle; and wherein said pressure insert (30) and said extraction insert (40) are conical with a conical angle that complements the conical angle. of the conical longitudinal hole and have dimensions such that when inserted into the conical longitudinal hole they are not in contact with each other and define a pressure chamber (50) for a drawing lubricant. insert and a drawing insert. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Pressure die for cold drawing and inserts for a pressure die

Background

The present invention relates to the sector of cold drawing of bars, metal wires or, more generally, long metal objects. More particularly, the present invention relates to a pressure die for cold drawing a metal bar or wire. The present invention also relates to a pair of pressing and drawing inserts configured for said pressing die.

State of the art

As is known, the process of drawing a wire or metal bar consists of introducing the wire or metal bar into a tool that reduces its diameter. Typically, the metal bar or wire undergoes a gradual reduction in diameter as it passes through dies with increasingly smaller drawing diameter.

Lubricants are used during the drawing process. Typically, lubricants are in solid form, such as powder or flake. However, wire drawing lubricants can also be in liquid form.

In order to force the lubricant into the die, pressure dies are known in which a step is carried out prior to the drawing phase itself, whose purpose is to increase the pressure of the lubricant so that it is transported together with the metal bar or wire during drawing.

Document IT 1269433 (Tecnovo S.r.l) describes a tool for drawing metal wires and bars, which comprises a support element, which is traversed by a passage, and a drawing element made of a very hard material, and is housed in the interior of the support element and provided with a hole coinciding with said passage. The support element is formed by at least two pieces that can be removably combined with each other to fix the drawing element in position, within the support element.

Document IT 1295286 (Tecnovo S.r.l.) describes a die for drawing metal bars or wires, with integral and rapid replacement of the drawing core and recovery thereof, which comprises a reinforcement provided with a through hole, in which said reinforcement accommodates removable an upper element and a drawing core separated from each other and aligned with said hole, in which the lower profile of said upper element is such that it fits perfectly with the entrance of the drawing core located below it.

Document EP 0679 112 (Paramount Die Co., Inc.) describes a set of dies for metal wires. US 2008/0173063 A1 describes a drawing system in which the drawing heat is distributed over two or more drawing inserts.

Summary of the invention

The present invention is applicable to any long metal element, including a tube, but typically a metal bar or wire. To promote simplicity, the present description will refer only to bars. However, in the present description and claims, the term "bar" is understood to comprise any long metallic element, such as a tube, bar or metal wire.

The Applicant has observed that the known pressure rows comprise two inserts separated by a metallic spacer, for example made of steel, or copper, or another metal, which is arranged between the two inserts to prevent contact between them, which would cause a breakage. , and to prevent lubricant leakage, which would cause a loss of pressure and, therefore, lower efficiency.

The drawing system described in US 2008/0173063 A1 comprises two or more drawing inserts 300, 400 and a pressure insert 200. The pressure insert 200 is kept in contact with the drawing insert 300. According to the Applicant, This configuration causes premature breakage of the pressure insert and/or the drawing insert that is in direct contact with the pressure insert. This occurs because the pressure insert is in direct contact with the first of the two drawing inserts and the pressures involved subject the inserts to high mechanical pressures.

Furthermore, the pressure insert is retained by a hole inside the male fastener 110 that is configured to engage with a thread inside the female row element 120. Therefore, it is necessary to machine the clamping element separately. male closure and the female element: the male element must be machined to form the hole for the pressure insert and the female body must be machined to form a tapered hole for the row inserts 300 and 400. Machining operations carried out on two separate elements They must be very precise and, therefore, expensive.

The thread between the male locking element and the female element is located at a relatively small diameter, so the locking force is necessarily limited.

The Applicant has defined the objective of providing a pressure die comprising only two inserts (a single pressure insert and a single drawing insert) that are axially separated from each other to provide a pressure chamber. In particular, the Applicant has defined the objective of providing a pressure die in which the two inserts are always in a configuration such that they are not axially in direct contact with each other or with a spacer.

The Applicant has also defined the objective of providing a pressure die of the aforementioned type in which the inserts can be mounted simply and quickly.

The Applicant has defined the objective of providing a pressure die of the aforementioned type in which the inserts, in particular the drawing insert, can be replaced simply and quickly. Indeed, the drawing insert is subject to rapid wear and must be replaced quite frequently.

These objectives, along with others, are achieved with a pressure die according to the present invention in which the pressure insert and the drawing insert both have a frustoconical shape with the same taper angle. The inserts are configured so that they can be inserted into a tapered bore of a spinneret housing, which has a taper angle complementary to that of the inserts. The dimensions of the two inserts are configured to leave a distance between them in the axial direction, creating a pressure chamber and avoiding the possibility that the two inserts may come into contact during use of the spinneret or due to incorrect assembly ( or imprecise) of the components. To keep the pressure insert in position with respect to the body, a ring nut is preferably provided.

According to a first aspect, the present invention relates to a pressure die comprising a die housing, a single pressure insert, a single drawing insert and a locking ring configured to lock the pressure insert with respect to said housing. of row,

wherein said spinneret casing comprises a conical longitudinal through hole having a single taper angle from a first inlet end of larger diameter to a second outlet end of smaller diameter;

wherein the pressing insert is inserted into the tapered longitudinal through hole and positioned near the entry end, wherein the drawing insert is inserted into the tapered longitudinal through hole and positioned near the exit end, and

wherein the pressure insert and the drawing insert are conical with a taper angle complementary to the taper angle of the conical longitudinal hole and have dimensions such that they are not in contact with each other and define a pressure chamber for a lubricant of wire drawing

Unlike the solution described in document US 2008/0173063 A1 there is a single drawing insert. According to the present invention, the drawing insert is never in contact with the pressure insert. Furthermore, in the present invention, both the drawing insert and the pressing insert are inserted into a conical hole formed in the die body. The single conical hole in the die body offers significant advantages during die forming, both in terms of the tolerances that can be obtained and machining costs.

The taper angle of the longitudinal through hole is preferably between 1° and 10°, more preferably between 1° and 6° and even more preferably between 1° and 4°.

According to preferred embodiments, the taper angle of the longitudinal through hole is 3°.

According to one embodiment, the spinneret housing is a male member and the lock ring is a threaded female member configured to engage a thread of the spinneret housing. This aspect is very advantageous. In fact, in the die casing according to the present invention, the conical through hole is formed for the only pressing insert and the only drawing insert. The locking ring (female) engages a thread on the outer surface of the spinneret housing. Therefore, the thread between the spinneret housing and the locking ring extends over a surface having a diameter larger than that of the solution described in US 2008/0173063 A1. Therefore, the locking action is more firm and reliable in the present invention. Furthermore, the hexagon formed at the top has a larger diameter and this improves the tightening capacity of the locking ring with respect to the spinneret housing.

The smaller diameter of the pressing insert is preferably larger than the larger diameter of the drawing insert.

According to a second aspect, the present invention relates to a pair of inserts, i.e. a kit, comprising a pressure insert and a drawing insert for a pressure die, the pressure die comprising: a die housing and a locking ring configured to lock the pressure insert with respect to said spinneret housing,

wherein said spinneret casing comprises a conical longitudinal through hole having a taper angle from a first inlet end of larger diameter to a second outlet end of smaller diameter;

wherein the pressure insert is configured to be inserted into the conical longitudinal through hole and positioned near the inlet end; wherein the drawing insert is configured to be inserted into the tapered longitudinal through hole and positioned near the exit end,

wherein said pressing insert and said drawing insert are conical with a taper angle that complements the taper angle of the conical longitudinal hole, and

wherein the smaller diameter of the pressure insert is larger than the larger diameter of the drawing insert, so that, when inserted in the conical longitudinal hole, they are not in contact with each other and define a pressure chamber for a lubricant of wire drawing

The taper angle is preferably between 1° and 10°. According to a preferred embodiment, the taper angle is 3°.

Brief description of the figures

There follows a detailed description of the present invention, given by way of non-limiting example, which should be read with reference to the accompanying drawings, in which:

• Figure 1 and Figure 2 are two longitudinal section views of the pressure die according to an embodiment of the present invention, whose difference consists in the machining tolerance of the inserts;

• Figures 3.1 and 3.2 show a front view and a longitudinal section view of the spinneret casing;

• Figures 4.1 and 4.2 show a front view and a longitudinal section view of the spinneret housing locking ring;

• Figures 5.1 and 5.2 show a pressure insert;

• Figure 5.3 shows another pressure insert according to the present invention; and

• Figures 6.1 and 6.2 show a drawing insert according to the present invention.

Detailed description

In Figures 1 and 2, a pressure die according to an embodiment of the present invention is shown schematically. In particular, Figures 1 and 2 are two longitudinal sections showing the same pressure row according to the present invention. However, depending on the machining tolerance, the two inserts may be arranged in different positions and may create a pressure chamber with a different size. In other words, their relative position may be different.

The pressure die is designated overall with the number 1. It comprises a die housing 10, a locking ring 20, a first insert 30 and a second insert 40. The first insert 30 is a pressure insert, while the second insert 40 is a wire drawing insert.

Depending on the diameter of the body to be drawn and/or the diameter reduction to be obtained, the pressure die 1 (and consequently, also the individual components) can have different dimensions. Solely as a non-limiting example, in the present description a die will be described for drawing a bar with an initial diameter of 5.5 mm, to obtain a final diameter of 4.7 mm, with a reduction of approximately 27%. Dies according to the present invention can be manufactured for larger or smaller diameters and for various percentages of diameter reduction.

In Figures 3.1 and 3.2, an embodiment of the die housing 10 is also shown. According to the embodiment shown, the die housing 10 comprises a substantially cylindrical male body with an outer surface provided with a thread 11. According to In one embodiment, the outer diameter is approximately 28 mm and comprises an outer surface M27x1.5. Obviously, this is an example and the die housing 10 could have a different diameter and/or could be threaded with a different thread. The outer surface of the spinneret housing preferably further comprises at least one groove 12 for an elastic sealing ring (O-ring).

The outer surface of the spinneret housing further preferably comprises a hexagon-shaped section 13.

The die casing 10 comprises a longitudinal through hole 14. The longitudinal through hole 14 is a conical hole. The taper angle 15 of the longitudinal through hole 14 (measured with respect to the longitudinal axis According to a preferred embodiment, the taper angle 15 is 3°. The largest diameter of the longitudinal through hole, always referring to the specific example, can be approximately 14 mm.

The taper angle 15 remains unchanged along the entire length of the conical longitudinal through hole, from a first inlet end (larger diameter) 141 to a second outlet end (smaller diameter) 142.

The spinneret housing 10 is preferably made of a metallic material, for example, steel and in particular, stainless steel.

The female locking ring 20 is configured to engage the male die housing 10 and lock the insert 30 within the longitudinal through hole 14. More specifically, the locking ring 20 comprises a substantially cylindrical body with a threaded hole 21 configured to engage to the external thread 11 of the spinneret housing 20. The head of the locking ring 20 comprises a longitudinal through hole 24. When the spinneret housing 10 and the locking ring 20 are connected to each other (by means of the external thread 11 of the die body 10 and the internal thread 21 of the locking ring 20), the X-X axis of the longitudinal through hole 14 of the die body 10 preferably coincides with the Y-Y axis of the longitudinal through hole 24 of the head of the locking ring 20. The longitudinal through hole 24 of the head of the locking ring 20 is preferably open, and tapered like a funnel towards the outside, as indicated by the number 27 in Figure 4.2.

Preferably, the locking ring 20 also comprises a hexagonal shaped section 23.

The outer surface of the locking ring 20 also preferably comprises a seat 22 for an elastic sealing ring (O-ring).

The locking ring 20 is preferably made of a metallic material, for example, steel and in particular, stainless steel.

Referring now to Figures 5.1 and 5.2, a pressure insert 30 suitable for mounting within the pressure row 1 according to Figures 1 and 2 will be described.

The pressure insert 30 is a substantially truncated conical body with a larger base 31 that corresponds to the inlet mouth of the bar (not shown) and a smaller base 32 that corresponds to the outlet of the bar. The direction of advance of the bar is indicated by the IN and OUT arrows.

The taper angle 35 of the drawing insert 40 corresponds (complements) the taper angle 15 of the longitudinal through hole 14 of the die casing 10. According to the present invention, the taper angle 35 (if necessary excluding the first section 33 ' in the proximity of the major base) is between 1° and 10°, preferably between 1° and 6° and even more preferably between 1° and 4°. According to a preferred embodiment, the taper angle 35 is 3°.

As shown in Figure 5.1, the pressure insert 30 comprises a suitably shaped longitudinal through hole 34. The longitudinal through hole 34 of the pressure insert 30 comprises a first more open section 341 defining the inlet bell, a second conical section 342, a third substantially cylindrical section 343 and an outlet bell 344 that opens outwardly in the direction the pressure chamber 50.

According to embodiments, the pressure insert 30 has a length of approximately 10 to 20 mm, preferably 10 to 15 mm and even more preferably 10 to 12 mm.

According to embodiments, the pressure insert 30 has a larger base 41 with a diameter D30 of approximately 10 to 20 mm, preferably 10 to 15 mm and even more preferably 14 to 15 mm.

According to embodiments, the substantially cylindrical third section 343 has a length of 1 to 7 mm, for example 2 mm.

The inlet hood may have an angle a of 80°, while the outlet hood may have an angle P of 60°.

Preferably, the pressure insert 30 is made from hard material, for example, sintered tungsten carbide, which optionally has a cobalt base.

Depending on the machining tolerance, the pressure insert can be in the position indicated in Figure 1 (maximum tolerance), in the position indicated in Figure 2 (minimum tolerance) or in any intermediate position. Figure 5.3 shows a variant of the pressure insert 30 in which no drawing occurs. The main difference lies precisely in that the second section 342 is also cylindrical with the same diameter as the third section 343. The diameter of the cylindrical section corresponds substantially to the diameter of the bar that passes through it.

Referring now to Figures 6.1 and 6.2, a drawing insert 40 suitable for mounting within the pressure die 1 will be described according to Figures 1 and 2.

The drawing insert 30 is a substantially truncated conical body with a larger base 41 that corresponds to the entry mouth of the bar (not shown) and a smaller base 42 that corresponds to the exit of the bar subjected to drawing.

The taper angle 45 of the drawing insert 40 corresponds (complements) with the taper angle 15 of the longitudinal through hole 14 of the die casing 10. According to the present invention, the taper angle 45 (if necessary excluding the first section 43' in the proximity of the major base) is between 1° and 10°, preferably between 1° and 6° and even more preferably between 1° and 4°. According to a preferred embodiment, the taper angle 45 is 3°.

As shown in Figure 6.1, the drawing insert 40 comprises a suitably shaped longitudinal through hole 44. The longitudinal through hole 44 of the drawing insert 40 comprises a first, more open section 441 that defines the inlet bell, a second conical section 442 that defines the surface for reducing the diameter of the bar, a third substantially cylindrical section 443 within the which consolidates the diameter of the drawn bar and an outlet bell 444 to discharge the drawn bar. Typically, drawing occurs in the last portion 442' of the second section 442.

According to embodiments, the reduction surface 442 of the drawing insert 40 forms an angle of 4° to 30°, for example 16°.

According to embodiments, the substantially cylindrical third section 443 has a length of 1 to 7 mm, for example 2 mm and has a diameter 444 of approximately 4 to 5 mm, for example 4.6 mm.

The outlet hood may have an angle P of 60°.

Preferably, the drawing insert 40 is made of a hard material, for example, sintered tungsten carbide, optionally based on cobalt.

The smaller base 31 of the pressure insert 30 has a diameter d30 that is larger than the diameter D40 of the larger base 41 of the drawing insert 40.

To assemble the pressure die 1 according to the present invention, first the drawing insert 40 is inserted into the through hole 14 of the die housing 10. The diameter of the larger base 41 is designed in such a way that the pressure insert drawing 40 is positioned near the smaller diameter end 142 of said hole (figure 1). Next, the pressure insert is also inserted into the through hole 14 of the spinneret housing and is positioned near the larger diameter end 141 of the through hole 14. The diameter of the smaller base 32 of the pressure insert 30 is always larger than that of the larger base 41 of the drawing insert 40. In this way, the two inserts 30, 40 never come into contact with each other and a pressure chamber 50 is created.

The locking ring 20 is then screwed to the die housing 10. By screwing the locking ring 20 to the die housing 10 (advantageously, via hexagons 13 and 23), the pressure insert 30 is retained within the die casing and is not at risk of being pushed out by the lubricant pressure created during bar drawing.

The pressure chamber 50 is configured to collect lubricant (not shown) drawn from a container upstream of row 1 and carried by the bar during its high speed movement within the pressure insert 30. The high pressure lubricant present in the pressure chamber 50 adheres to the surface of the bar before entering the drawing insert 40.

If it is necessary to replace the drawing insert 40 and/or the pressure insert 30, the locking ring 20 is unscrewed and the two inserts 30, 40 are pushed opposite to the direction of insertion. In this way, the two inserts 30, 40 are released and can be removed and replaced.

Advantageously, the through hole 14 is smooth and not threaded. Likewise, the conical outer surface of the two inserts 30, 40 is smooth and not threaded.

Claims (8)

1. Pressure die (1) comprising a die housing (10), a single pressure insert (30), a single drawing insert (40) and a locking ring (20) configured to lock the pressure insert (30) with respect to said row casing (10), wherein said spinneret housing (10) comprises a conical longitudinal through hole (14) having a single taper angle (15) from a first inlet end of larger diameter (15) to a second outlet end of smaller diameter (142); wherein the pressure insert (30) is inserted into the conical longitudinal through hole (14) and positioned near the inlet end (141); wherein the drawing insert (40) is inserted into the conical longitudinal through hole (14) and positioned near the exit end (142); and in which the pressure insert (30) and the drawing insert (40) are conical with a conicity angle (35, 45) complementary to the conicity angle (15) of the conical longitudinal hole (14) and have dimensions such which are not in contact with each other and define a pressure chamber (50) for a drawing lubricant. 2. Pressure die (1) according to claim 1, wherein the conicity angle (15) of said longitudinal through hole (14) is between 1° and 10°. 3. Pressure die (1) according to claim 2, wherein the conicity angle (15) of said longitudinal through hole (14) is 3°. 4. Pressure die (1) according to claim 1, 2 or 3, wherein said die housing (10) is a male member and said locking ring (20) is a threaded female member configured to engage a thread ( 11) of said row casing (10). 5. Pressure die (1) according to any one of the preceding claims, wherein the smaller diameter (32) of the pressure insert (30) is larger than the larger diameter (41) of the drawing insert (40). 6. Kit (30, 40) comprising a pressure insert (30) and a drawing insert (40) for a pressure die (1), the pressure die comprising: a die housing (10) and a ring locking device (20) configured to lock the pressure insert (30) with respect to said spinneret housing (10), wherein said spinneret housing (10) comprises a conical longitudinal through hole (14) having an angle of taper (15) from a first inlet end of larger diameter (15) to a second outlet end of smaller diameter (142); wherein the pressure insert (30) is configured to be inserted into the conical longitudinal through hole (14) and positioned near the inlet end (141); wherein the drawing insert (40) is configured to be inserted into the conical longitudinal through hole (14) and positioned near the exit end (142), wherein said pressure insert (30) and said drawing insert (40) are conical with a taper angle (35, 45) that complements the taper angle (15) of the conical longitudinal hole (14) and in which the smaller diameter (32) of the pressure insert (30) is greater than the larger diameter (41) of the drawing insert (40) so that, when they are inserted in the conical longitudinal hole (14), they are not in contact with each other and define a pressure chamber (50) for a drawing lubricant. 7. Kit (30, 40) according to claim 6, wherein said conical angle (15) is between 1° and 10°. 8. Kit (30, 40) according to claim 7, wherein said conical angle (15) is 3°.