WO2018138459A1 - Device for thermally insulating a machining attachment and machining attachment provided with such a device - Google Patents

Abstract

Device for thermally insulating a machining attachment (1) intended to secure a machining tool (3) to a machine-tool spindle, of the type having a body (2) of axis of revolution Z, a first end (20) of which comprises means for mounting the said machining tool (3) and a second end (21) of which comprises means of assembly with said spindle, said body (2) having passing through it a passage of axis Z, opening at each of the first and second ends (20, 21), said passage being intended for the circulation of a lubricating fluid between the machine-tool and said machining tool (3) and being equipped, at said first and second ends (20, 21) with a first end-piece (7) for fluidic connection to said tool (3) and with a second end-piece (4) for fluidic connection to said spindle. The device comprises a thermally insulated pipe (5) configured to be inserted inside said passage and to collect said lubricating fluid.

Description

 Thermal insulation device of a machining attachment and machining attachment provided with such

 The present invention relates to a device for thermal insulation of a machining attachment intended to join a machining tool to a spindle of a machine tool, said attachment being of the type having a body of axis of revolution Z, a first end of which comprises means for mounting said machining tool and a second end comprises means for assembly with said pin, said body being traversed by a Z-axis passage, opening at each level; first and second ends, said passage being intended for the circulation of a lubricating fluid between the machine tool and said machining tool and being provided, at said first and second ends, respectively with a first nozzle of fluid connection with said tool and a second fluidic connection tip with said pin.

 The present application also relates to a machining attachment provided with thermal insulation device according to the invention.

 Conventionally, many mechanical parts required by the industry are obtained by different methods of machining material removal of various materials, differentiating from each other by their technical and technological characteristics specifically adapted to the applications considered.

The search for increased productivity gains has led in recent years to an evolution of machining processes often tending to impose harsher cutting conditions, resulting in particular in an increase in cutting speeds and in the advance, at less with regard to materials whose machinability is already mastered. In addition, some areas of advanced technology, such as aeronautics, aerospace, nuclear or automotive, require for their development to have parts designed from innovative materials, with increasingly efficient features , but whose machining can prove to be delicate and supposes the respect of a certain number of precautions.

 Like processes involving high cutting speeds or those used to produce materials for the production of parts for advanced fields, many processes for machining by material removal are currently accompanied by an increase in temperatures at the contact interfaces between the machining tool, the part being manufactured, and the chips generated by the transformation of the block of starting material. This is especially true when the shaped material is thermally refractory, this is particularly the case of titanium alloys or stainless steels.

 In order to prevent the problems that can be generated during the implementation of conventional material removal machining processes and related to the increase of temperatures in the cutting area, such as in particular premature wear of cutting tools, a degradation of the surface integrity of the part being manufactured, as well as geometric dispersions on the final product, it has been imagined to cool to a strongly negative temperature all the elements involved, by the implementation of lubricants cryogenic, such as for example liquid nitrogen or carbon dioxide, in the lubrication circuit extending from a machining machine to a tool and a workpiece, through a machining attachment.

In addition, new environmental standards recently in force have also encouraged manufacturers to use cryogenic lubricants, more environmentally friendly, to replace them with traditional lubricating products of a harmful nature.

 Although cryogenic machining has proven to be advantageous both from an environmental point of view and to overcome the problems related to the increases in cutting temperature mentioned above, it has however been observed that this technology is not entirely satisfactory and does not allow not always achieve the desired goals.

 Thus, in particular have been reported problems related to too abrupt cooling of the machining attachment, or problems due to a significant deposition of frost on the outer shell of the attachment of the tool. Furthermore, it has also been observed that the use of cryogenic fluid is likely to cause a cold bonding of the body of the attachment of the tool in the spindle of the machine tool, or to cause a transmission. unintentional cold to the spindle during long machining, or even significant condensation after use.

 These problems not only inevitably affect the structural integrity of the parts involved, but also result in an unacceptable slowdown of the rates due to difficulties dismantling the attachments stuck in the spindle by the deposition of frost, even in the worst case by a geometric or mechanical degradation of the spindle of the machine tool.

The present invention aims to overcome all of these disadvantages by providing a thermal insulation device of a machining attachment advantageously to limit the transfer of heat energy between the lubricating fluid and the outer surface of the body attachment. Another goal of the invention is to provide such a thermal insulation device having a structure that is both simple and compatible with the different ranges of machining attachments available on the market today.

 For this purpose, the present invention relates to a device for thermal insulation of a machining attachment of the kind indicated in the preamble, characterized in that it comprises a thermally insulated duct configured to be inserted into said passage, and to accommodate said lubricating fluid.

 Preferably, the conduit is made of a material having thermal insulation properties and has a length corresponding at least to the distance between the first and second connection ends.

 According to a first variant embodiment, the conduit comprises at least a first tube and a second tube.

 The latter can be interconnected by first complementary form of assembly means, and be movable in translation relative to each other in opposite directions along their axis of revolution Z.

 The invention furthermore provides that in this configuration, the first complementary form assembly means comprise elastic return means.

 According to an additional characteristic, the first and / or the second tube and the first and / or the second fluidic connection piece are interconnected by means of complementary form of assembly.

The present invention also provides an alternative embodiment in which the conduit comprises said second fluidic connection piece with which it is formed in one piece. In this case, the duct advantageously has a peripheral double wall comprising an inner peripheral wall and an outer peripheral wall delimiting between them a space filled by a thermal insulation means, the latter being able to be chosen from the list comprising the vacuum, a foam expansive.

 Preferably, the peripheral wall of the outer tube may further have areas of different thicknesses, this to further contribute to the thermal insulation effect of the device.

 In this variant embodiment, the second connection piece may also include the assembly means with said pin.

 Whatever the embodiment variant considered, it is furthermore provided that the duct is supplemented by sealing means and is made of a material having thermal insulation properties chosen from the list comprising polytetrafluoroethylene, stainless steel , titanium, polyurethane foam or expanded polystyrene.

Moreover, the present invention also relates to a machining attachment intended for securing a machining tool with a spindle of a machine tool, of the type having a body of axis of revolution Z, a first end of which comprises means for mounting said machining tool and a second end comprises means for assembling with said pin, said elongated body being traversed by a Z-axis passage, opening at each of the first and second ends, said passage being intended for the circulation of a lubricating fluid between the machine tool and said machining tool and being provided at said first and second ends with a first fluidic connection piece with said tool and a second fluid connection piece with said pin. characterized in that it comprises a thermal insulation device as previously defined.

 Other features and advantages of the invention will emerge from the detailed description which follows, referring to embodiments of the attachment of machining according to the invention given solely for information and not limitation.

 The understanding of this description will be facilitated with reference to the accompanying drawings, in which:

 FIG. 1 illustrates a perspective view of a machining attachment according to the invention, of type

"ISO DIN", and fitted with a platen milling cutter,

FIG. 2 illustrates a semi-exploded view of the machining attachment of FIG. 1, equipped with a thermally insulated conduit according to a first variant embodiment,

 FIG. 3 is a longitudinal sectional view of the machining attachment of FIG. 1 equipped with the thermally insulated duct of FIG. 2,

 FIG. 4 represents a semi-exploded view of the machining attachment of FIG. 1, equipped with a thermally insulated conduit according to a second variant embodiment, and

 FIG. 5 is a longitudinal sectional view of the machining attachment of FIG. 1 equipped with the thermally insulated duct of FIG. 4.

 With reference to the figures, in the variant embodiments illustrated, the machining attachment 1 according to the invention comprises a metal body 2, of conical shape, of axis of revolution Z, of which a first end

20 comprises means for mounting a machining tool 3, such as for example a platen mill, and a second end 21 comprises means for assembling with a spindle of a machining machine (not shown). In this respect, in the embodiment variant illustrated, the machining attachment 1 is of the "ISO DIN" type and comprises for this purpose a pull tab 4, provided with a male end 40 arranged to cooperate with a female end (not shown) of a gripping member of a spindle of a machine tool.

 The body 2 is also crossed by a passage

22 of axis of revolution Z, for the circulation of a lubricating fluid from the machine tool to said machining tool 3. The passage 22 opens at each of the first and second ends 20, 21, where it communicates respectively with a first nozzle 7 of fluid connection with said tool 3, and a second nozzle for fluid connection with said pin, the latter being defined by the pull tab 4.

 According to the invention, the machining attachment 1 further comprises a thermally insulated conduit inserted into the passage 22, and inside which the lubricating fluid circulates. Such a structure advantageously avoids the aforementioned drawbacks related to the use of cryogenic fluids.

 In the embodiment variant illustrated in the figures

2 and 3, the machining attachment 1 is equipped with a duct 5 made of a material having thermal insulation properties, such as for example polytetrafluoroethylene (PTFE), stainless steel, titanium, a foam polyurethane or expanded polystyrene, or any other equivalent material. This duct 5 extends over the entire length of the passage 22, from the tool 3 to the spindle of the machine tool, its two ends being inserted respectively into the first fluidic connection piece 7 and the pull tab 4. By elsewhere, in the example illustrated, the duct 5 comprises a first tubular section 50 and a second tubular section 51 interconnected by first complementary form of assembly means, and movable in translation relative to one another in opposite directions along

1 'Z axis. In fact, as seen in FIG. 3, the first section 50 has a female end 52 in which is fitted a male end 53 of the second tubular section 51. A compression spring 8 is also engaged in the compressed state around the male end 53, between the first section 50 and the second section 51.

 Such a structure makes it possible to compensate for the effect of thermal shrinkage induced by the passage of a cryogenic fluid on the component parts of the conduit 5. Indeed, a retraction of the first and second sections 50,

51 results in an expansion of the compression spring 8. The latter then pushes the first and second sections 50, 51 towards respectively the first end 20 and the second end 21 of the body 2 and therefore to the tool 3 and the spindle of the Machine tool. The length of the conduit 5 therefore remains constant regardless of the temperature of the lubricating fluid flowing through it, which makes it possible to ensure perfect sealing at the ends of this insulating assembly.

 It should also be noted that a plurality of seals 9 are arranged at the level of the assembly zone between the first and second sections 50, 51 as well as at the junction regions with the tool 3 or with the spindle of the machine tool.

 Moreover, in the variant embodiment illustrated in FIGS. 4 and 5, the duct 6 is also made of a material chosen from the list cited above for the duct 5, preferably titanium. It is advantageously formed in one piece with the second fluidic connection end, which in this case is defined by said pull tab 4.

In fact, the duct 6 here has a double peripheral wall formed of a first inner tube engaged in a second outer tube. The duct 6 thus comprises an inner peripheral wall 60 and an outer peripheral wall 61, welded to one another at their level. ends while the vacuum is formed in the space 62 between the inner 60 and outer 61 peripheral walls, which makes it possible to contribute even more to the thermal insulation effect already resulting from the use of titanium.

 Furthermore, the outer peripheral wall 61 has areas of different thicknesses to ensure greater thermal insulation of the machining attachment 1 at corresponding locations thereof.

 It should also be noted that although the invention has been described in connection with a machining attachment of the "ISO DIN" type, it also applies to an "HSK" type machining attachment that differs from the previous in particular by the structure of the assembly means with a spindle of a machine tool.

Claims

1. Device for thermal insulation of a machining attachment (1) for joining a machining tool (3) with a spindle of a machine tool, of the type having a body (2) of an axis of revolution Z whose first end (20) comprises means for mounting said machining tool (3) and a second end (21) comprises means for assembly with said spindle, said body (2) being traversed by a Z-axis passage (22) opening at each of the first and second ends (20, 21), said passage (22) being intended for the circulation of a lubricating fluid between the machine tool and said tool for machining (3) and being provided at said first and second ends (20, 21) with a first fluidic connection piece (7) with said tool (3) and a second fluidic connection piece (3). (4) with said pin, said thermal insulation device being characterized in that it comprises a conduit (5, 6) therm ically isolated configured to be inserted into said passage (22), and to accommodate said lubricating fluid.  2. Thermal insulation device according to claim 1, characterized in that said duct (5, 6) is made of a material having thermal insulation properties and has a length corresponding at least to the distance between the first and second connection end pieces (7, 4) included in said machining attachment (1).  3. Thermal insulation device according to any one of claims 1 or 2, characterized in that said duct (5, 6) comprises at least a first tube (50, 60) and a second tube (51, 61). 4. Thermal insulation device according to claim 3, characterized in that said first and second tubes (50, 51) are interconnected by first complementary form of assembly means, and in that they are movable in translation relative to each other in opposite directions along their axis of revolution Z.  5. Thermal insulation device according to claim 4, characterized in that said first complementary form of assembly means comprise elastic return means.  6. Thermal insulation device according to any one of claims 4 or 5, characterized in that the first and / or second tube (s) (50, 51) and the first and / or second end (s) fluid connection (7, 4) are interconnected by means of complementary form of assembly.  7. Thermal insulation device according to any one of claims 1 to 3, characterized in that said duct (6) comprises said second fluidic connection piece (4) and is formed integrally therewith.  8. thermal insulation device according to claim 7, characterized in that said duct (6) has a peripheral double wall having an inner peripheral wall (60) and an outer peripheral wall (61) delimiting between them a space (62) filled by a thermal insulation means.  9. Thermal insulation device according to claim 8, characterized in that said thermal insulation means is selected from the list comprising vacuum, an expansive foam.  10. Thermal insulation device according to any one of claims 8 or 9, characterized in that the outer peripheral wall (61) has areas of different thicknesses. 11. Thermal insulation device according to any one of claims 7 to 10, characterized in that said second connection piece (4) comprises the connecting means (40) with said pin. 12. Thermal insulation device according to any one of the preceding claims, characterized in that said duct (5, 6) is provided with sealing means (9).  13. Thermal insulation device according to any one of the preceding claims, characterized in that said duct (5, 6) is made of a material having thermal insulation properties selected from the list comprising polytetrafluoroethylene, steel stainless, titanium, polyurethane foam or expanded polystyrene.  14. Machining attachment (1) for securing a machining tool (3) with a spindle of a machine tool, said attachment being of the type having a body (2) of axis of revolution Z a first end (20) of which comprises means for mounting said machining tool (3) and a second end (21) comprises means for assembling with said spindle, said body (2) being traversed by a passage (22) Z-axis, opening at each of the first and second ends (20, 21), said passage (22) being intended for the circulation of a lubricating fluid between the machine tool and said machining tool (3). ) and being provided, at said first and second ends (20, 21), with a first fluidic connection piece (7) with said tool (3) and with a second fluidic connection piece (4) with said pin, characterized in that it comprises a thermal insulation device according to any one of the claims 1 to 13 inserted in said passage (22).