EP0449926A1 - Dispositifs et structures mecaniques - Google Patents

Dispositifs et structures mecaniques

Info

Publication number
EP0449926A1
EP0449926A1 EP19900900943 EP90900943A EP0449926A1 EP 0449926 A1 EP0449926 A1 EP 0449926A1 EP 19900900943 EP19900900943 EP 19900900943 EP 90900943 A EP90900943 A EP 90900943A EP 0449926 A1 EP0449926 A1 EP 0449926A1
Authority
EP
European Patent Office
Prior art keywords
members
rod
base
mounting structure
mounting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19900900943
Other languages
German (de)
English (en)
Inventor
Kevin 15 Rooksmead Road Lindsey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BTG International Ltd
Original Assignee
National Research Development Corp UK
British Technology Group Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National Research Development Corp UK, British Technology Group Ltd filed Critical National Research Development Corp UK
Publication of EP0449926A1 publication Critical patent/EP0449926A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q1/00—Members which are comprised in the general build-up of a form of machine, particularly relatively large fixed members
    • B23Q1/01—Frames, beds, pillars or like members; Arrangement of ways

Definitions

  • This Invention relates to mechanical devices and structures. In particular, It relates to structures having an affinity with those described In our pending British Patent Application No.2194182A.
  • a mounting device comprising six rod-like members the ends of which are rigidly coupled together to form a substantially tetrahedral structure, three of the members which are not co-planar having fixedly coupled to them mounting means for, for example, a machine tool, and the other three members constituting a triangular base and, suitably, having fixedly coupled to them means for locating a workpiece on which the machine tool is to work.
  • the six members may all be of equal length, yielding a regular tetrahedral structure, or the three members having the mounting means coupled to them may be of different length from the remaining three members constituting the base.
  • the published Application describes the advantageous physical and mechanical properties (stiffness, vibration response, and thermal response characteristics) which may be attained by the use of such a structure.
  • a mounting structure which comprises a rigid base and a first set of rod-like members disposed pyramidally with one end of each rigidly coupled to corresponding ends of the others at a common vertex and the other end of each rigidly coupled to the base, even when the rod-like members of the said first set are more than three in number and/or the base is not itself formed simply of a further set of three rod-like members.
  • a mounting structure which comprises a rigid base and a first set of at least three rod-like members disposed pyramidally with one end of each rigidly coupled to corresponding ends of the others at a common vertex and the other end of each rigidly coupled to the base, wherein the base is other than simply a triangular structure formed of a further set of three rod-like members.
  • Such a mounting structure may also include mounting means comprising a rigid member fixedly coupled to the pyramidallydisposed rod-like members and in spaced relationship with the base.
  • the base of such a mounting structure may be a more complicated three-dimensional triangulated structure, or may be, for example, a solid rigid metal plate or other structure to which the said other ends of the pyramidally disposed rod-like members are rigidly coupled at spaced-apart locations; and the plate or other structure may itself be an integral part of a separately existing machine or other article.
  • the rod-like members of the said first set may be three or four in number, and the base may have the form of a tetrahedron or a square pyramid, with the said other ends of the members of the first set secured to respecitive vertices of the base forming a triangle or a square respectively.
  • the coupling together of the said one ends of the rod-like members at their common vertex may be such that their pyramidal disposition is, in effect, that of a somewhat truncated pyramid.
  • Figure 1 is a front elevational view of a tetrahedral machine tool mounting device as described in U.K. Patent Application No.2194182A;
  • Figure 2 is a lateral sectional view, on the line II-II of Figure 1, of the mounting device shown in Figure 1;
  • Figure 3 is a section, on a larger scale, through a workpiece mounting table for a machine tool shown in Figure 1 and 2;
  • Figure 4 is a section, on a larger scale, through a toolholder shown in Figures 1 and 2;
  • Figure 5 represents the geometrical structure of the mounting device shown in Figures 1 and 2;
  • Figures 6, 7 and 8 represent geometrical structures according to the invention, with tetrahedral stiffening components
  • Figures 9, 10, 11 and 12 are practical realisations of the structures of Figures 5, 6, 7 and 8.
  • the tetrahedral mounting structure shown in Figures 1 and 2 includes six rod-like members 1a - 1f. Each member comprises a tubular outer strut 2a - 2f enclosing a tensile rod 3a - 3f. At each apex of the tetrahedral structure is a hollow sphere 4a 4d. Each sphere comprises a pair of mating hemispheres 5a - 5d, 6a - 6d. The halves of the hemispheres are held together by threaded bolts 7. Each sphere abuts the outer strut of three of the rod-like members and is clamped thereto by means of bolts 8 attached to the ends of the corresponding enclosed tensile rod.
  • a machine tool holder 9 Mounted on the rod-like members 1a, 1b and 1c which are remote from the base constituted by members 1d, 1e, and 1f, is a machine tool holder 9.
  • the machine tool holder is clamped to rod-like members 1a, 1b and 1c by means of threaded bolts 10 and space blocks 11.
  • the mounting interface is preferably replicated, as described and claimed in our co-pending Application No. (Reference No. 132386) having the same filing date as the present Application.
  • the machine tool holder 9 and the hollow sphere 4d have respective bores 12 and 21 coaxial with the machine principal axis 13, through which passes a drive shaft 14 carrying an air bearing spindle having a rotor 15A and a stator 15B and a grinding tool 16, as shown in Figure 2 and (on a larger scale) in Figure 4.
  • the stator has an extension 15C to provide an extended viscous damping workface 15D.
  • Mounted on the base rod-like members 1d, 1a and 1f is a vee slideway 17 bearing a workpiece holder 18 to impart linear motion to a workpiece 19 beneath the grinding tool 16.
  • the workpiece holder is provided with a dividing strip 18A.
  • Interfaces 18B are provided with a viscous damping medium.
  • the slideway has a hollowed-out portion 20 so that the wall thickness is similar to that of the other structural components.
  • the geometry of the damping interface can be matched to the modes of the vibration expected or most needing attenuation, for instance the plane vertical damping interfaces between the driving strip of the sliding workpiece holder 18 and the matching slot in the vee slideway 17 will respond efficiently to horizontal mode vibrations from the drive to the sliding workpiece holder and the principal axis (vertical) vibrations; whereas the cylindrical damping interface between the stator of the air bearing rotary spindle 15 and the bore of the machine tool holder 9 will respond efficiently to torsional vibrations from the rotary spindle and to principal axis (vertical) vibrations.
  • This vibration damping principle using viscous means can also, as described in published British Application No. 2194182A, be applied to the rod-like members 1a - 1f, which may contain viscous damping fluid; and the damping affect may be increased if damping interfaces are machined or built into or on, the components, which can be done without compromising structural static stiffness, i.e. the damping is essentially in parallel, rather than series, with the structural loop so the net result of adding the viscous damping can only be an increase of structure dynamic stiffness.
  • the thickness of the viscous damping layer i.e. the gap between the solid surfaces thus comprising the damping interface
  • the thickness of the viscous damping layer can be 50 micrometres or greater with the chosen damping fluids so that no tribological (fretting, pick up, wear) problems will arise with dimensional tolerances within normal engineering practice. Close proximity of the two surfaces, as on some existing machines, is not needed; again avoiding tribological problems, and the inconsistent vibration damping which frequently results from stick-slip when the two surfaces are in close proximity or intermittent contact.
  • FIG. 5 The geometrical form of the known mounting device shown in Figures 1 and 2 is represented diagrammatically in Figure 5 as a regular tetrahedron whose edges represent the rod-like members la to If as shown in the corresponding Figure 9 which is a simplified perspective view of the mounting structure shown in Figures 1 and 2.
  • the machine principal axis 13 is represented in both Figures 5 and 9 by a broken line referenced PA.
  • the base of the structure instead of being constituted by the three rod-like members 1d, 1e, and 1f and the spheres 4a, 4b and 4c by which they are joined, is a solid metal plate or other structure to which the lower ends of the members 1a, 1b and 1c are rigidly coupled at spaced-apart locations.
  • the plate or other structure may be free-standing, or may itself be an integral part of a separately existing article such as a machine on which, for example, ancillary equipment is mounted by means of the pyramidally disposed members 1a, 1b and 1c and mounting means secured (like the tool holder 9 shown Figures 1 and 2) to the members 1a, 1b and 1c in spaced relationship with the said plate or other structure.
  • the pyramidally disposed members 1a, 1b and 1c, with their common spherical joint 4d may be mounted on the plate or other structure not (or not solely) for the purpose of mounting ancillary equipment upon it but rather (or additionally) for imparting added stiffness or rigidity to the plate or structure.
  • the set of pyramidally-disposed rod-like members having their mutually remote ends rigidly coupled to the base are more than three in number, for example four or five, usually but not necessarily of equal length, arranged in the form of a four-edged or five-edged pyramid; and, as in the above-described first embodiment, the base to which the mutually remote ends of those members are secured may be either a plate or panel which may be free-standing or a component part of a separatelyexisting entity, or some other structure which may in this case be formed of a set of four or five rod-like members coupled end-to-end in a preferably planar four- or five-sided polygon (with or without the addition of additional rod-like members to provide a fully triangulated structure) and a further set of four or five rod-like members each having one end rigidly coupled at a common vertex to the corresponding ends of the others and having its other end (like the said other end of each of the said first set of rod-
  • a further embodiment of a mounting structure in accordance with the invention is represented diagrammatically and in perspective outline in Figures 6 and 10 respectively, in which the pyramidally disposed members 1a, 1b and 1c are rigidly coupled to a base 22 which is itself in the form of an inverted regular tetrahedron and is constituted by co-planar rod-like members 1d', 1e', and 1f coupled together by spherical joints 4a', 4b' and 4c', together with further rod-like members 1a', 1b' and 1c' coupled together at their lower ends by a spherical joint 4d' and each coupled at its upper end to a respective one, of the joints 4a', 4b' and 4c'.
  • the base 22 is, in fact, a mirror Image of the structure shown in Figure 9, and the details of its construction may be identical with those shown in Figure 2. Since all the rod-like members shown in Figure 10 are of equal length, the base 22 provides a collinear extension PA' of the principal axis PA and increased working space within the structure in which mounting means (for instance, like the tool holder 9 and workpiece holder 17, 18 shown in Figures 1 and 2) may be secured in place on the members 1a, 1b and 1c or 1a', 1b' and 1c' or 1d', 1e' and 1f for mounting tools and workpieces or co-operating components of other functional apparatus in a desired spaced relationship to one another along the extended principal axis.
  • mounting means for instance, like the tool holder 9 and workpiece holder 17, 18 shown in Figures 1 and 2
  • FIG. 6 Another embodiment, not shown in the drawings but closely analogous to that represented, in Figures 6 and 10, has the overall form not of two tetrahedra back-to-back as in Figures 6 and 10 but of two square pyramids back-to-back, in that it comprises a first set of four rod-like members disposed pyramidally with one end of each rigidly coupled to the corresponding ends of each of the other three at a common vertex and the other end of each rigidly coupled to a base in the form of a square pyramid comprising eight rod-like members - four rigidly coupled end-to-end, to form a square at whose corners respective ones of the first set are mounted, and four more each having one end mounted at a respective one of those corners and having their other ends coupled together in a pyramidal structure which mirrors that of the first set of members.
  • Such a structure is not fully triangulated (unless it also comprises a further member secured as a diagonal of the square) but nevertheless is a very favourable structure, with a large available working space for mounting tools or the like within its bounds, and provides all the advantages of a fully triangulated structure, virtually uncompromised.
  • Structural symmetry may be almost entirely maintained, and other advantageous properties remain again largely uncompromised if, as in a further embodiment represented in Figures 7 and 11, a base 22' is provided which creates an auxilliary principal axis PA" intersecting the axis PA at an angle of 90° (as shown) or at some other selected angle.
  • the base 22' comprises, to that end, the members 1d', 1e' and 1f and spherical joints 4a', 4b' and 4c' as shown in Figure 10, and also the members 1a', 1b' and 1c' having one end of each coupled together by spherical joint 4d'; but in this embodiment, although the members 1a' and 1c' are secured as before to the joints 4a' and 4c' respectively, they and the member 1b' are swung together through 90° about the line of member 1f' and the end of member 1b' which is remote from the joint 4d' is rigidly located by a further spherical joint 23 and further rod-like members 24, 25 and 26 (similarly constructed) which are secured between the joint 23 and, respectively, the joints 4a', 4b' and 4c'.
  • This arrangement allows for mounting means to be secured in place, along the axis PA, on the members 1a, 1b and 1c and/or the members 1d', 1e' and 1f and also, along the auxilliary axis PA", on the members 1a', 1b' and 1c' and/or the members 1f, 24 and 26. It will be seen that if the angle between the axes PA and PA" is to be 90° the member 25 will be of greater length than that of all the other rod-like members, and care is therefore needed to keep its resonant frequency near or equal to that of those other members.
  • the base 22' comprises a non-regular first tetrahedron (having edges constituted by the members 24, 25 and 26 and vertices 4a', 4b' 4c' and 23 to three of which the members 1a, 1b and 1c are rigidly coupled) and, mounted over one of the lower triangular sides of this first tetrahedron, the pyramidal structure constituted by the members 1a', 1b' and 1c' and their common coupling joint 4d'.
  • each of the lower triangular sides of the tetrahedral base 22 shown in Figure 10 may have fitted over it a pyramidal structure like that constituted by the members 1a, 1b, 1c and 4d, and each of these will then enable mounting means to be fitted along respective ones of three auxilliary axes each intersecting the axis PA at an angle.
  • those pyramidal structures be isosceles; if they are of unequal lengths, as represented in Figures 8 and 12, their common vertex may be offset, if that is required for some special purpose, from the principal axis PA as defined by the symmetrical case.
  • vibration damping may be introduced at mounting decoupling points, in accordance with our co-pending Application No. (Reference 132386).
  • mounting structures according to the invention is not limited to machine tools. They may be used in any application, such as surface metrology where a high degree of stiffness and rigidity is required.
  • Such an additive feature might be provided, for instance, for the critical mounting of a cutting tool, sensor, or measuring device on a structurally or environmentally flawed existing entity or structure, or as a cost-effective (that is, avoiding the need to discard the whole flawed entity/structure) improvement to an existent entity/structure.
  • An example of such an additive fixture would be the addition of three hemispherical mounting interfaces to an existent entity/structure, each of the three hemispherical interfaces then having secured to it an end of one of the three rod-like members of the pyramidal additive fixture.
  • Such a three-point mounting enables a tool or other device to be mounted with minimum self-stressing at the mounting.
  • a mounting structure which comprises a rigid base and a first set of at least three rod-like members disposed pyramidally with one end of each rigidly coupled to corresponding ends of the others at a common vertex and the other end of each rigidly coupled to the base, wherein the base is other than simply a triangular structure formed of a further set of three rod-like members.
  • a mounting structure as claimed in Claim 1 and including mounting means comprising a rigid member fixedly coupled to the pyramidally-disposed rod-like members and in spaced relationship with the base.
  • the said rod-like members are of two-part construction, each comprising a strut member and a tensile member.
  • each rod-like member includes a tubular member having a tensile rod therethrough.
  • the base is a metal plate or other structure to which the said other ends of the pyramidally disposed rod-like members are rigidly coupled at spaced-apart locations.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Vibration Prevention Devices (AREA)
  • Machine Tool Units (AREA)

Abstract

Une structrure de montage très rigide comporte au moins trois éléments en forme de tige disposés en pyramide (1a, 1b, 1c) et accouplés de manière rigide à une extrémité (4d), leurs autres extrémités étant accouplées de manière rigide à une base (22) pour rigidifier celle-ci et/ou monter un dispositif tel qu'un outil ou un instrument par rapport à celle-ci. Ces trois éléments disposés en pyramide (1a, 1b, 1c) peuvent être montés sur une base tétrahédrique (22), ou bien quatre de ces éléments sur les angles respectifs d'une pyramide carrée, pour former avec celle-ci une ossature sur laquelle monter, par exemple, une machine-outil ou un instrument de mesure, la base étant de préférence formée d'éléments en forme de tige similaires; ou encore la base peut être une structure plate ou une autre structure d'une machine ou autre entité existant séparément.
EP19900900943 1988-12-22 1989-12-20 Dispositifs et structures mecaniques Withdrawn EP0449926A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8829931 1988-12-22
GB888829931A GB8829931D0 (en) 1988-12-22 1988-12-22 Mechanical devices and structures

Publications (1)

Publication Number Publication Date
EP0449926A1 true EP0449926A1 (fr) 1991-10-09

Family

ID=10648942

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900900943 Withdrawn EP0449926A1 (fr) 1988-12-22 1989-12-20 Dispositifs et structures mecaniques

Country Status (5)

Country Link
EP (1) EP0449926A1 (fr)
JP (1) JPH04502430A (fr)
GB (1) GB8829931D0 (fr)
RU (1) RU2051778C1 (fr)
WO (1) WO1990006831A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5541622A (en) * 1990-07-24 1996-07-30 Incontrol Solutions, Inc. Miniature isometric joystick
SE512242C2 (sv) 1998-06-18 2000-02-14 Flexprop Production Ab Verktygshållare
USD813918S1 (en) 2016-01-28 2018-03-27 Autodesk, Inc. Three dimensional (3D) delta printer

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1775125A1 (de) * 1968-07-08 1971-05-27 Willy Herold Raum- oder Flaechengitterwerk aus Staeben und Knotenpunkten
FR2137257B1 (fr) * 1971-05-17 1973-05-11 Thorel Jean
FR2145065A5 (fr) * 1971-07-08 1973-02-16 Guichard Rene
GB2088987A (en) * 1980-11-12 1982-06-16 Marconi Co Ltd Drive Systems
AU572478B2 (en) * 1982-12-09 1988-05-12 Geodome Space Frames Pty. Ltd. Space frame structure
ZA843821B (en) * 1983-05-23 1986-02-26 Assunta Elizabeth Vitale Modular construction units
JPH0615783B2 (ja) * 1985-07-25 1994-03-02 淳次郎 小野田 展開構造物
GB8619699D0 (en) * 1986-08-13 1986-09-24 Lindsey K Mounting devices

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9006831A1 *

Also Published As

Publication number Publication date
RU2051778C1 (ru) 1996-01-10
GB8829931D0 (en) 1989-02-15
JPH04502430A (ja) 1992-05-07
WO1990006831A1 (fr) 1990-06-28

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