EP2702350A1 - Machine portable de mesure à bras articulés à cinq axes de haute précision - Google Patents

Machine portable de mesure à bras articulés à cinq axes de haute précision

Info

Publication number
EP2702350A1
EP2702350A1 EP12717865.5A EP12717865A EP2702350A1 EP 2702350 A1 EP2702350 A1 EP 2702350A1 EP 12717865 A EP12717865 A EP 12717865A EP 2702350 A1 EP2702350 A1 EP 2702350A1
Authority
EP
European Patent Office
Prior art keywords
arm
joint
measuring machine
axes
probe
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Withdrawn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
EP12717865.5A
Other languages
German (de)
English (en)
Inventor
Nicola TOMELLERI
Monica TOMELLERI
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.)
Tomelleri Engineering Srl
Original Assignee
Tomelleri Engineering Srl
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 Tomelleri Engineering Srl filed Critical Tomelleri Engineering Srl
Publication of EP2702350A1 publication Critical patent/EP2702350A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
    • G01B5/004—Measuring arrangements characterised by the use of mechanical techniques for measuring coordinates of points
    • G01B5/008—Measuring arrangements characterised by the use of mechanical techniques for measuring coordinates of points using coordinate measuring machines

Definitions

  • This invention relates to a portable measuring machine with five axis articulated arms characterized by the high precision which can be reached and in that the second joint is balanced.
  • the portable machines with articulated arms which will also be indicated by the acronym AMM (Articulated Measuring Machine)
  • AMM Articleated Measuring Machine
  • CMMs Coordinat Measuring Machines
  • the AMMs compared with the CMMs, have the advantage of the lower cost, but they have the disadvantage of the lower precision.
  • the AMMs are mainly characterized, as will be illustrated below in Figure 1, by the fact that they have three joints, each of which is equipped with three axes, between which two connecting arms are interposed, whilst the third joint provides the two axes to the measuring probe for orienting it in the required direction.
  • the measuring probe may also consist of a Laser Head which allows the surfaces to be scanned, and in that case it may be equipped with a further rotary axis so that the machine is equipped overall with seven axes, but this invention does not regard that scanning device.
  • AMMs equipped with five axes wherein it is the second axis to be equipped with a single joint, and that solution is mainly present in machines designed for measuring pipes which do not require high levels of measurement precision.
  • AMMs are not very precise if compared with CMMs, even though in some cases it is sufficient for measuring medium-sized parts for which a high level of precision is not required, whilst it is always insufficient for measuring small-sized parts, when the tolerances have very small values of around a few thousandths of a millimetre.
  • the current AMMs are not able to precisely measure the diameter of a 50 H6 hole since the precision which may be reached by the machine is, in the best cases, equal to the tolerance required for the diameter, whilst the precision of the measuring instrument is normally required to be greater than the precision required for the part.
  • Another drawback of the existing AMMs designed for measuring parts is that they have at least six axes, and that the balancing system in them supports the weight present up to the second joint, so the final joint together with the probe must be supported by the operator, and this always results in the risk of falling with the danger of collision.
  • This lack of total balancing of the joints of the machine means that the operator cannot perform the measuring with the gentleness required for high precision measurements, and the operator must also move the arms to the vertical rest position between one measuring step and the next.
  • This invention is proposed for overcoming the aforementioned drawbacks of the AMMs, for measuring small and medium-sized parts.
  • the main aim of this invention is to considerably increase the measurement precision.
  • Another aim of this invention is to balance the weight of the second joint and of the probe preventing the danger of falling and therefore allowing the precision measurements to be performed gently, and without the need for the operator to replace the arms in the vertical rest position between one measuring step and the next.
  • a further aim of this invention is to allow an easy access for measuring the part when it is mounted on the operating machine, adopting a tripod with special features and performance.
  • Yet another aim of this invention is to allow an easy access to the measurement on the surfaces located on the other side of the machine.
  • the machine may be equipped with a system for balancing the weight of the second joint and of the probe, and it may also be fixed to a tripod to support it during movement equipped with an extensible adjustment part.
  • Figure 1 schematically shows an AMM equipped with three joints with two axes each.
  • Figure 2 schematically shows the AMM according to this invention with a vertical axis and two joints.
  • Figure 3 schematically shows a cross-section along the axis of the first arm of the AMM according to this invention showing the balancing system of the third joint.
  • Figure 4 schematically shows a cross-section at right angles to the axis of the first arm of the AMM according to this invention showing the balancing system of the third joint.
  • Figure 5 schematically shows the AMM according to this invention fixed to a tripod with an extensible adjustment part.
  • Figure 6 schematically shows the AMM according to this invention equipped with a balancing counterweight.
  • Figure 1 shows an AMM of the type with three joints, with two axes for each joint. More specifically, the figure shows the base 10 of the machine fixed to the plane 11 , the first joint 1 with the two axes "a” and “b”, the joint 2 with its two axes "c” and “d” and the joint 3 with its two axes "e” and "f '.
  • the joint 1 is supported by the base 10 and by the column 11, whilst the first arm 13 is interposed between the joint 1 and the joint 2 and the second arm 14 is interposed between the joint 2 and the joint 3. Lastly, the probe 15 is fixed to the joint 3.
  • Figure 2 shows an AMM made according to this invention, having an axis Al and two joints SI and S2. It consists of a base 20 fixed to the plane 11, which is integral with the column 21, which supports the axis Al consisting of the axis of vertical rotation "a" about which the first arm 22 is fixed and rotates according to said vertical axis. At the end of the first arm there is the first joint SI with two axes "c” and “d” to which the second arm, consisting of the two parts 24 and 25 integral with each other, is fixed and free to rotate according to said two axes "c" and "d".
  • the balancing device 23 which exerts a suitable torque on the second arm is applied to the arm 22 in such a way as to balance at least partly the torque due to its weight, that of the joint S2 and that of the probe.
  • Figure 3 schematically shows the balancing system present on the end of the first arm 22 and which allows the torque due to its weight, that of the joint S2 and that of the probe to be at least partly balanced.
  • the drawing shows a cross-section passing through axis "c".
  • the spring 27 which is suitably pre-tensioned so as to exert the required balancing torque on the bushing 23 is applied on the structure of the arm 22.
  • the bushing 23 is integral with the shaft 26, which has the degree of freedom for rotating about the axis "c", and therefore imparts the balancing torque to all the parts connected to it, comprising the second arm consisting of parts 24 and 25, the second joint S2 and the probe.
  • Figure 4 schematically shows the balancing system present on the end of the first arm with a view from IV.
  • the bushing 23 is integral with the shaft 26 so as to to transmit to it the torque required for balancing all the subsequent parts connected to it and which load their weight on it.
  • the axis "c” and “d” may adopt angles between minimum and maximum values provided by stop positions prepared on the two axes.
  • the axis "c” may adopt angles between the minimum value “cm” and the maximum value “cM”
  • the axis “d” may adopt angles between a minimum value "dm” and a maximum value “dM”.
  • Two aims are achieved with these two stop positions, on the one hand the balancing torque provided by the pre-tensioning of the spring is always sufficiently close to the torque exerted by the weight forces, and on the other hand the changes in the angles of the two axes is limited so as to allow the measurements to be performed within the planned range of work.
  • the pre-tensioning angle of the spring and the angles given to the two axes "c" and “d” are such as to achieve a good balancing condition which prevents the falling of the probe in all the conditions when it is released by the operator.
  • An alternative balancing solution is that of fixing a counterweight to the second arm, located on the other side of the axis "c" and in a position approximately opposite the centre of gravity of the second joint, which, however, could lead to obstruction problems.
  • the probe may be of the electronic or fixed type even if this second solution appears preferable.
  • the measurement ball is made integral, through the stylus which supports it, with axes "e" and “f of the second joint, and the measurement is enabled either by a measurement pick-up pushbutton or by using an automatic probe which enables the measurement when a predetermined force is exerted on the probe.
  • Figure 5 shows the AMM fixed to a tripod which is adjustable in height equipped with an adjustable lateral extension for allowing the machine to be moved close to the part when it is still in the machine.
  • the AMM of the invention 50 is fixed on a horizontal beam 57 which is free to rotate about a horizontal axis "h" relative to the other horizontal beam 56, which is in turn free to rotate about the axis "g" relative to the vertical sleeve 55.
  • the vertical sleeve is adjustable in height being slidable inside the pipe 54, so as to allow the measuring machine, and in particular its probe 26, to be moved to the height of the part to be measured after having clamped the locking knobs 58.
  • the two beams 56 and 57 are free to rotate about the axes "g" and "h” so it is possible to move the AMM off centre by the desired quantity with the limit given by the length of the two beams.
  • the tripod 51 is positioned on the three supporting struts 53 so that its has a stable position, whilst when moving from one position to another the three wheels 52 which detach the struts from the floor are lowered.
  • the beam 57 must be folded above the beam 56 in such a way that the AMM is centred on the tripod thereby preventing the overbalancing from causing the tipping of the tripod.
  • Figure 6 shows the AMM in which the balancing of the second arm and of the second joint is achieved by means of the counterweights 62 and 63 fixed to the second arm by the rod 61.
  • the main aim of this invention to considerably increase the measuring precision is achieved thanks to the fact that the number of axes of the machine is equal to five instead of six, and that it is balanced thereby preventing the operator from exerting loads which deform the machine.
  • the aim of allowing an easy access for measuring the part when it is mounted on the operating machine is achieved by adopting a tripod with the features described.
  • the another aim of facilitating access to the measurement on the surfaces located on the other side of the machine is achieved thanks to the particular shape of the second arm.
  • a particular embodiment of the machine according to this invention provides that the weight of the probe to be balanced with a small counterweight positioned symmetrically relative to the axis "f '.
  • a particular embodiment provides that the probe is made interchangeable with a device for fast coupling to the second joint.
  • a different solution relates to the type of probe, or a different shape of the second arm, or the adoption of a different system for balancing the second arm of the second joint and the probe.
  • a laser head is fixed to the second joint instead of the probe.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • A Measuring Device Byusing Mechanical Method (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)

Abstract

La présente invention concerne une machine de mesure à bras articulé possédant cinq axes, qui est capable d'atteindre un niveau de précision très élevé. Les bras de la machine et la sonde sont équilibrés, de sorte que la machine est plus sûre et moins soumise aux charges que l'opérateur exerce pour la supporter. La machine est conçue pour être fixée sur un trépied mobile équipé d'une rallonge ajustable, ce qui permet à des pièces d'être mesurées sur la machine.
EP12717865.5A 2011-04-29 2012-03-28 Machine portable de mesure à bras articulés à cinq axes de haute précision Withdrawn EP2702350A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT000085A ITVR20110085A1 (it) 2011-04-29 2011-04-29 Macchina di misura portatile a bracci articolati di grande precisione a cinque assi.
PCT/IB2012/051479 WO2012146989A1 (fr) 2011-04-29 2012-03-28 Machine portable de mesure à bras articulés à cinq axes de haute précision

Publications (1)

Publication Number Publication Date
EP2702350A1 true EP2702350A1 (fr) 2014-03-05

Family

ID=44281132

Family Applications (1)

Application Number Title Priority Date Filing Date
EP12717865.5A Withdrawn EP2702350A1 (fr) 2011-04-29 2012-03-28 Machine portable de mesure à bras articulés à cinq axes de haute précision

Country Status (3)

Country Link
EP (1) EP2702350A1 (fr)
IT (1) ITVR20110085A1 (fr)
WO (1) WO2012146989A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013004353A1 (de) * 2013-03-14 2014-09-18 Rosswag Gmbh Messvorrichtung, Fertigungsvorrichtung und Prüfverfahren
CN105241404A (zh) * 2015-09-29 2016-01-13 爱佩仪中测（成都）精密仪器有限公司 利于坐标测量数值准确性的多臂测量仪
CN105443655A (zh) * 2015-12-10 2016-03-30 合肥工业大学 利用内置弯曲弹簧实现力平衡和机构限位的摆动关节

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4592697A (en) * 1983-04-26 1986-06-03 Kabushiki Kaisha Kobe Seiko Sho Gravity balancing device for rocking arm
US6253458B1 (en) * 1998-12-08 2001-07-03 Faro Technologies, Inc. Adjustable counterbalance mechanism for a coordinate measurement machine
GB0011371D0 (en) * 2000-05-12 2000-06-28 Renishaw Plc Probe head
US7073271B2 (en) * 2002-02-14 2006-07-11 Faro Technologies Inc. Portable coordinate measurement machine
ATE362598T1 (de) * 2002-03-19 2007-06-15 Faro Tech Inc Dreibeinstativ
US7908757B2 (en) * 2008-10-16 2011-03-22 Hexagon Metrology, Inc. Articulating measuring arm with laser scanner

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2012146989A1 *

Also Published As

Publication number Publication date
WO2012146989A1 (fr) 2012-11-01
ITVR20110085A1 (it) 2012-10-30

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