MANDREL ASSEMBLY FOR A TUBE BENDING MACHINE

Abstract

A mandrel assembly for a tube bending machine has a mandrel body, a mandrel rod, a series of articulation elements connected to one another and to the mandrel body through respective cylindrical or spherical hinges, and a network of lubricant transport channels formed through the mandrel body and communicating with a lubricant feed passage formed along the mandrel rod. The network of lubricant transport channels has a plurality of lubricant outlet ports arranged on the distal end or on a peripheral surface of the mandrel body. A plurality of through-holes extending along a longitudinal direction of the respective articulation element is formed through each of the articulation elements. The through-holes are configured to convey a lubricant to a front side of an extreme distal articulation element of the series of articulation elements. The extreme distal articulation element has a deflector element.

Claims

1. A mandrel assembly for a tube bending machine, comprising: a mandrel body configured to be inserted inside a tube to be bent, the mandrel body comprising a proximal end and a distal end, a mandrel rod rigidly connected to the proximal end of the mandrel body and configured to support and move the mandrel body, a series of articulation elements arranged at the distal end of the mandrel body, each articulation element of the series of articulation elements being connected to an adjacent articulation element of the series of articulation elements through a respective cylindrical or spherical hinge, wherein the series of articulation elements comprises an extreme proximal articulation element connected to the distal end of the mandrel body through a cylindrical or spherical hinge, and a network of lubricant transport channels formed through the mandrel body and communicating with a lubricant feed passage formed along the mandrel rod, the network of lubricant transport channels comprising a plurality of lubricant outlet ports arranged on at least one of the distal end and a peripheral surface of the mandrel body, wherein a plurality of through-holes extending along a longitudinal direction of the respective articulation element is formed through each of the articulation elements, the through-holes being configured to convey a lubricant to a front side of an extreme distal articulation element of the series of articulation elements, and wherein the extreme distal articulation element comprises a deflector element fixed to the front side of the extreme distal articulation element, opposite the respective through-holes, the deflector element being configured to radially deflect outwardly the lubricant exiting the respective through-holes.

2. The mandrel assembly of claim 1, wherein each articulation element comprises a central portion through which each articulation element of the series of articulation elements is connected to the adjacent articulation element of the series of articulation elements, and a blanket portion attached to and arranged around the central portion, and wherein the through-holes are entirely formed through the blanket portion.

3. The mandrel assembly of claim 1, wherein the through-holes have a minimum diameter greater than or equal to 4 mm.

4. The mandrel assembly of claim 1, wherein the network of lubricant transport channels comprises a central manifold centrally formed in the mandrel body and directly communicating with the lubricant feed passage, and wherein a plurality of radial channels extending radially toward the peripheral surface of the mandrel body branch off from the central manifold.

5. The mandrel assembly of claim 4, wherein a respective longitudinal channel extending longitudinally toward the distal end of the mandrel body branches off from each of the radial channels and leads to an outside of the mandrel body at the distal end, with a respective lubricant outlet port of the plurality of lubricant outlet ports.

6. The mandrel assembly of claim 4, wherein the radial channels lead to an outside of the mandrel body at the peripheral surface of the mandrel body, with respective lubricant outlet ports of the plurality of lubricant outlet ports.

7. The mandrel assembly of claim 6, wherein the respective lubricant outlet ports lead to at least one surface groove formed on the peripheral surface of the mandrel body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further features and advantages of the present invention will become apparent from the detailed description that follows, provided purely by way of non-limiting example with reference to the accompanying drawings, wherein

[0021] FIG. 1 is a schematic view of a tube bending machine provided with a mandrel assembly

[0022] FIG. 2 is a perspective view of a mandrel assembly according to the present invention

[0023] FIG. 3 is a sectional view of the mandrel assembly of FIG. 2, inserted into a tube, and

[0024] FIG. 4 is a sectional view of the mandrel assembly of FIG. 2.

DETAILED DESCRIPTION

[0025] In FIG. 1, an example of a tube bending machine is schematically represented, in which a tube T is being processed. The tube bending machine comprises a die 10, which has on its lateral surface a groove with a curved path of a predetermined radius around a z-axis, perpendicular to the longitudinal axis of the tube T, a pair of clamping blocks 14, and a bending slide 16 which is rotatable around the z-axis. Initially, the tube T is clamped between the clamping blocks 14 and extends forward beyond the die 10 and the bending slide 16. Subsequently, with the tube T clamped not only between the clamping blocks 14, but also between the die 10 and the bending slide 16, the bending slide 16 is rotated around the z-axis, thus wrapping the tube T around the die 10 and generating in the tube a bend with a mean radius substantially corresponding to the mean radius of the groove of the die 10.

[0026] It is understood that the machine described above is provided solely by way of non-limiting example, as the present invention may be applied to different types of tube bending machines.

[0027] The tube bending machine comprises a mandrel assembly, globally denoted by 20, configured to be inserted inside the tube T and to support the tube profile from the inside during the bending process.

[0028] The mandrel assembly 20 comprises a mandrel body 21 configured to be inserted inside the tube T. The mandrel body 21 comprises a proximal end 21a and a distal end 21b, and is laterally delimited by a peripheral surface 21c, which is opposed to an internal surface of the tube T. For the purposes of the present description, the terms proximal and distal respectively indicate closer and farther with respect to a control system A of the mandrel assembly 20, schematically represented in FIG. 1.

[0029] The mandrel assembly 20 further comprises a mandrel rod 23 rigidly connected to the proximal end 21a of the mandrel body 21 and configured to support and move the mandrel body 21. To this end, the mandrel rod 23 is supported by the control system A onboard the machine, which is operable to move the rod along the longitudinal axis of the tube T.

[0030] The mandrel assembly 20 further comprises a series of articulation elements 24, 25, 26 arranged at the distal end 21b of the mandrel body 21, which are articulately connected to one another and to the mandrel body 21. The articulation elements 24, 25, 26, commonly known as balls, thanks to their articulated connections, are capable of following the deformation of the tube T during the bending process, providing support to the wall of the tube T. In the illustrated example, there are three articulation elements; however, it is understood that the number of articulation elements may vary, for example, it may be two or more than three. Each articulation element of the series of articulation elements 24-26 is connected to an adjacent articulation element of the series of articulation elements 24-26 through a respective cylindrical or spherical hinge 28, 29. The extreme proximal articulation element 24 of the series of articulation elements 24-26 is also connected to the distal end 21b of the mandrel body 21 through a cylindrical or spherical hinge 27.

[0031] More precisely, each articulation element 24-26 comprises a central portion 24a-26a through which each articulation element 24-26 is connected to an adjacent articulation element 24-26 (forming the hinges 28 and 29), and a blanket portion 24b-26b attached to and arranged around the central portion 24a-26a. The central portion 24a of the extreme proximal articulation element 24 is also connected to a central insert 21d fixed to the mandrel body 21 at the distal end 21b, forming the hinge 27. Advantageously, the blanket portions 24b-26b may be made of a different material from the central portions 24a-26a. For example, the blanket portions 24b-26b may be made of a material with a lower friction coefficient compared to the material of the tube.

[0032] The control system of the mandrel assembly 20 includes a lubricant supply system B, configured to supply a lubricant, such as a lubricant gel, to the mandrel assembly 20, and to lubricate the surfaces of the mandrel assembly 20 in contact with the interior of the tube T. To this end, the lubricant supply system B includes a pump connected to a lubricant feed passage 23a formed along the mandrel rod 23.

[0033] A network of lubricant transport channels is formed through the mandrel body 21, communicating with the lubricant feed passage 23a, as shown in FIGS. 2 to 4.

[0034] In the illustrated example, the network of channels comprises a central manifold 31 formed centrally in the mandrel body 21 and directly communicating with the lubricant feed passage 23a. From the central manifold 31, a plurality of radial channels 32 extend radially toward the peripheral surface 21c of the mandrel body 21. From each of the radial channels 32, a respective longitudinal channel 33 extends longitudinally toward the distal end 21b of the mandrel body and opens to the exterior of the mandrel body 21 at the distal end 21b, through a respective lubricant outlet port 34. Additionally, the radial channels 32 open to the exterior of the mandrel body 21 at the peripheral surface 21c, with respective lubricant outlet ports 36. The lubricant outlet ports 36 open into at least one surface groove 35 formed on the peripheral surface 21c of the mandrel body 21. In the illustrated example, the surface groove 35 is part of a network of surface grooves formed on the peripheral surface 21c of the mandrel body 21. Some grooves of the network extend in the circumferential direction, while others extend in the longitudinal direction of the peripheral surface 21.

[0035] A plurality of through-holes 37 is formed through each of the articulation elements 24-26, extending along the longitudinal direction of the respective articulation element 24-26. The through-holes 37 are configured to convey lubricant to the front side of the extreme distal articulation element 26 of the series of articulation elements 24-26.

[0036] More precisely, the through-holes 37 are entirely formed through the blanket portion 24b-26b of each articulation element 24-26. In other words, each through-hole 37 is entirely surrounded by the blanket portion 24b-26b and does not border the central portion 24a-26a. In this way, the through-holes 37 can be manufactured in a very simple manner.

[0037] The through-holes 37 may have a minimum diameter equal to or greater than 4 mm. Such a dimension is recommended when using high-viscosity lubricants, such as lubricant gels. However, it is understood that the present invention is not limited to this type of lubricant, and that it is possible to use lower viscosity lubricants, such as oils, and therefore, the through-holes of the articulation elements may have smaller diameters.

[0038] Advantageously, the extreme distal articulation element 26 comprises a deflector element 38 fixed to the front side of the extreme distal articulation element 26, and including a revolution surface 38a with a curved profile arranged opposite the respective through-holes 37. The deflector element 38 is configured to radially deflect outwardly the lubricant exiting the through-holes 37 of the extreme distal articulation element 26. This feature improves the distribution of the lubricant on the internal surface of the tube T.