WO2009037317A1

WO2009037317A1 - Reference and locking system, checking apparatus and checking method

Info

Publication number: WO2009037317A1
Application number: PCT/EP2008/062448
Authority: WO
Inventors: Riccardo Cipriani; Stefano Romagnoli
Original assignee: Marposs Societa' Per Azioni
Priority date: 2007-09-19
Filing date: 2008-09-18
Publication date: 2009-03-26
Also published as: ITBO20070636A1

Abstract

A reference and locking system for a mechanical piece to be checked includes a support base, a reference nosepiece fixed to the support base, and a locking assembly, with a thrust device and a transmission mechanism, which keeps the mechanical piece urged against reference surfaces of the nosepiece at a checking position. The transmission mechanism is generally L-shaped and includes a fastening portion applying to the mechanical piece to be checked a locking force having components lying along both the longitudinal direction and a transversal direction. The reference and locking system can be part of an optoelectronic checking apparatus and can be used in a method for checking the mechanical piece, as far as dimensions and/or form deviation are concerned.

Description

DESCRIPTION

«REFERENCE AND LOCKING SYSTEM, CHECKING APPARATUS AND CHECKING METHOD»

Technical Field

The present invention relates to a reference and locking system for a mechanical piece to be checked, comprising a stationary part with a support base and a reference nosepiece which is fixed to the support base and defines a longitudinal direction, the reference nosepiece including an opening with reference surfaces adapted to cooperate with the mechanical piece to be checked at a checking position; and a locking assembly, adapted to keep the mechanical piece to be checked urged against the reference surfaces of the reference nosepiece, and including a thrust device and a transmission mechanism, the thrust device being adapted to urge the transmission mechanism against the mechanical piece to be checked.

The present invention also relates to an optoelectronic checking apparatus including such a reference and locking system.

The present invention further relates to a method for checking dimensions and form deviation of a mechanical piece, including the steps of positioning the mechanical piece to be checked on a reference nosepiece defining a longitudinal direction; generating a locking force for positioning the mechanical piece in a checking position; generating a clamping force for clamping the mechanical piece in the checking position, carrying out the checking of dimensions and/or form deviation of the mechanical piece by means of a detection device of the optoelectronic type adapted to provide signals indicative of the position of component parts of the mechanical piece to be checked, the signals being adapted to be processed by a processing unit; removing the locking force and the clamping force; and removing the mechanical piece.

Background art

There are known hard disk storage units, or "hard disks", for storing and recalling data, that are employed in electronic systems such as computers. Hard disks typically include one or more heads with magnetic read/write elements that are connected to sliders and are placed near a surface of a rotating magnetic disk. When the magnetic disk is driven into rotation, a thin air cushion forms between the disk and the slider, enabling the latter to "float" over the disk at a distance which is in the range of a few tens of nanometers, or even less, in the current hard disks. In the course of the disk rotation, the magnetic read/write elements can be used to read/write bits of data along a magnetic track on the magnetic disk. It is known that the heads employed in the known hard disks are very complex and delicate and thus are checked before the assembly in the hard disks. Generally, the heads are checked once they have been assembled in "Head Gimbal Assembly" (HGA) or one or more HGA have been assembled in a "Head Stack Assembly" (HSA) . Typically, the HGA includes a head with an associated slider, and a resilient thin plate to which the head is connected by means of a joint. The thin plates have one end, opposite with respect to the end carrying the head, which is connected to a E-shaped support or "E-block" having a plurality of mutually parallel wings. The assembly of the E-block and the HGAs is called HSA and is used for reading or writing on one face or both the faces of one or more magnetic disks. The HSA also includes a bearing which couples the HSA to stationary component parts of the hard disk and enables the former to rotate under the control of a motor of the VCM ("Voice Coil Motor") type, for moving the magnetic heads on the magnetic disks . Checking operations carried out on the HSA, before the latter is assembled in the hard disk, typically include dimensional and attitude checking of the heads and of the associated sliders. Such checking operations are carried out by dedicated systems that comprise a support structure, reference and locking devices for the HSA to be checked for referring and locking the HSA in the support structure in a checking position, checking devices, for example of the optical type, for checking the conformity of the dimension and attitude characteristics of the HSA with the project specifications, and loading/unloading devices for positioning the HSA in a checking position and for removing it when the checking ends. There are known various devices for referring and locking HSAs to be checked. For instance, a device for locking and referring HSAs including thrust springs for urging the HSA bearing in abutment against a V-shaped wall integral with the support structure has been implemented by the applicant of the present patent application and is shown in figures 1 and 2.

The reference and locking device 1 includes a support base 2 whereon a reference nosepiece 3 defining a longitudinal axis Z is fixed. The reference nosepiece 3 includes a longitudinal hole 4 having an upper opening adapted to cooperate with a threaded end portion, or tang 11, of an HSA bearing (illustrated only in figure 2 for the sake of simplicity and clarity) . The longitudinal hole 4 is shaped in such a way as to include longitudinal reference surfaces 6 and 7 that are convergent so as to form a V-shaped seat. The tang is inserted in the upper opening of the longitudinal hole 4 and is urged in a checking position against the V-shaped seat 8 by a force which acts substantially along a direction X perpendicular to the axis Z and is applied, for example, by a horizontal spring 9 integral with the nosepiece 3 which is actuated by a pneumatic actuator 15 not illustrated in figure 1 for the sake of clarity. Figure 2 illustrates in a very simplified way a transversal section along a plane XY transversal to the axis Z of the reference and locking device 1 which shows how the spring 9 urges the HSA tang 11 against the V-shaped seat 8 by means of a mechanical transmission element 10. Figure 1 shows an axial movement linear gauge 16 which controls the position of the mechanical transmission element 10. Then, for the purpose of preventing the HSA from moving with respect to the checking position in the course of the subsequent checking operations, that also include for instance the insertion of a measuring comb 12 between the HGA, a thrust lying substantially along the axis Z is applied on the HSA by a floating ball (not illustrated for the sake of clarity) of a clamping device 13 so as to urge suitable first surfaces of the HSA in abutment against a suitable second surface 14 of the nosepiece 3.

As frictions inevitably occur between the tang 11 of the HSA bearing and the walls of the longitudinal hole 4 of the nosepiece 3, it is possible that, under the thrust applied by the spring 9, the HSA moves or rises and does not take the correct position.

When afterwards the clamping device 13 is actuated, so clamping the HSA against the surface 14 of the reference nosepiece 3, the HSA can take an incorrect checking position and thus introduces an error in the subsequent dimensional and attitude checkings. Moreover, during the clamping phase, the threaded tang 11 of the HSA bearing can seize owing to the incorrect reference position taken by the HSA.

Disclosure of the invention

Object of the present invention is to provide a reference and locking system, a checking apparatus and a checking method that enable to ensure a checking position for an HSA to be checked which is accurate and can be repeated, and to prevent component parts of the HSA from suffering damages. This and other objects are achieved by a reference and locking system according to claim 1, a checking apparatus according to claim 8 and a checking method according to claim 9. A reference and locking system according to the present invention involves particular characteristics of constructive simplicity, limited layout dimensions and reduced costs of implementation.

Brief Description of the Drawings

The invention is now described with reference to the enclosed sheets of drawings, given by way of non limiting examples, wherein: figure 1 is a perspective view of a known reference and locking device; figure 2 is a simplified transversal section of the reference and locking device of figure 1 ; figure 3 is a perspective view of a reference and locking system according to the present invention; figure 4 is a perspective view of a longitudinal section on a plane XZ of a detail of the reference and locking system of figure 3; figure 5 is a simplified section on the plane XZ of the detail of figure 4 with an HSA to be checked in a different operative condition; figure 6 is a perspective view of some components of a checking system for HSAs including the reference and locking system; and figure 7 is a perspective view of a known checking system or optoelectronic apparatus for checking HSAs.

Best Mode for Carrying Out the Invention

A reference and locking system 20 according to the present invention for a mechanical piece such as an HSA 43 to be checked, is illustrated in figures 3 to 6. The reference and locking system 20 includes a stationary part with a support base 21 and a reference nosepiece 22 fixed thereto. The reference nosepiece 22 is shaped in such a way as to comprise a longitudinal through hole or opening 23 defining a longitudinal direction Z. The opening 23 includes a first end portion 24 and reference surfaces with two longitudinal convergent walls 40, 41 so as to form a V-shaped seat 46 adapted for coupling to an end portion, or tang 42, of a bearing of the HSA 43, the latter including wings 48, 49 (partially and schematically illustrated only in figure 5) . The cooperation between the tang 42 and the reference surfaces including the V-shaped seat 46 defines a checking position of the HSA 43. The opening 23 further includes a second end portion 25 adapted for coupling to the support base 21 by means of a pin 44 which is visible in figure 5 and not illustrated in figure 4, and a central portion 26 which has larger dimensions than the end portions 24 and 25. A locking assembly adapted to keep the mechanical piece 43 to be checked at the checking position defined by the contact between the tang 42 and the reference surfaces (walls 40 and 41) of the reference nosepiece includes a thrust device and a transmission mechanism 27. The transmission mechanism 27 is housed in the central portion of opening 23 and includes a central body 28 with a projection 29 which comprises a longitudinal threaded hole for a longitudinal threaded pre-stroke pin 31. An upper part of the central body 28 includes a first threaded hole 32, which is arranged substantially along a direction X transversal to the direction Z, and a second hole 33, communicating with the hole 32, which is longitudinally arranged substantially along the direction Z. A thrust element, for example a pin 34, of the transmission mechanism 27 is removably and adjustably connected to the central body 28, more specifically is arranged in the hole 33 protruding from it, and is locked in seat by a threaded locking pin 35 screwed into the threaded hole 32. The thrust element or pin 34 defines a fastening portion of the transmission mechanism 27 that, according to a different embodiment, can be integrally formed with the central body 28. The transmission mechanism 27 is substantially L-shaped and an end portion 39 of the thrust pin 34 is adapted for contacting the tang 42 of the HSA 43 for keeping the latter urged in a reference position, as it will be hereinafter disclosed in more detail. The central body 28 is connected to the stationary part, advantageously to the nosepiece 22 by means of a rotation pin 36 which enables the transmission mechanism 27 to rotate about a direction Y perpendicular to the directions X and Z. The above-mentioned thrust device of the locking assembly is, for example, of the pneumatic type and includes a piston 38 and a cylinder 45, the latter being connected and referred to the support base 21 and acting along a longitudinal direction. More specifically, the piston 38 applies a force from the bottom upwards upon the projection 29 of the central body 28, substantially along the longitudinal direction Z. Thanks to the force applied by the piston 38, the central body 28 rotates in a clockwise direction (with respect to the arrangement of figures 3-5) about the rotation pin 36, so that the upper end 39 of the fastening portion with the thrust pin 34 moves along a downward arc trajectory.

The reference and locking system 20 further includes a transversal urging device, for example a coil spring 37 which is substantially arranged along the direction X transversal with respect to the axis Z. The spring 37 has one end connected to the nosepiece 22 and a second end connected to the central body 28, and urges the latter which rotates in a counterclockwise direction (with respect to the view of figures 3-5) in a rest position of the transmission mechanism 27. Such rest position, shown in figure 4, is defined by the abutment occurring between the pre-stroke pin 31 and a transversal surface of the nosepiece 22, wherein the thrust pin 34 is substantially coaxial with the end portion 24 of the hole 23, not contacting the wall of the hole 23.

The operation of the reference and locking system 20 for the HSA 43 to be checked will be herein described in more detail.

At the beginning of the operation the transmission mechanism 27 is in a rest condition and the pneumatic piston is retracted and does not contact the projection 29 of the central body 28. In such a condition, the coil spring 37 is not opposed by the pneumatic piston 38 and urges the transmission mechanism 27 in the rest position. While the transmission mechanism 27 is in the rest position, the HSA 43 is positioned on the reference nosepiece 22, in particular the tang 42 of the bearing is inserted in the end portion 24 of the hole 23, and the thrust pin 34 is partly arranged inside the tang 42 of the bearing. As previously mentioned, before carrying out the dimensional and attitude checking operations of the HSA 43, it is necessary to refer and fix the latter, for example to the reference nosepiece 22, by means of the locking assembly. For this purpose, the pneumatic piston 38 is actuated and, opposing the force applied by the coil spring 37, rotates the central body 28 in a clockwise direction and the thrust pin 34 which is integral with it. By virtue of the rotation of the central body 28, the end portion 39 of the thrust pin 34 moves along a downward arc trajectory in a clockwise direction, touches the tang 42 of the bearing of the HSA 43, and applies (figure 5) a locking force which keeps it urged against the reference surfaces of the opening 23 defined by walls 40, 41 of the V-shaped seat 46. By virtue of the described trajectory, the locking force which is generated by the longitudinal thrust of the piston 38 and is applied by the end portion 39 of the thrust pin 34 on the bearing tang 42 has a component lying along the direction X urging the HSA 43 in a checking condition, and a component lying along the direction Z, from the top downwards, opposing and preventing possible raising of the HSA, that can be caused as previously mentioned by frictions between the tang 42 and surfaces of the hole 23, during the displacement towards the checking position. Once reached the checking position, for preventing the HSA 43 from displacing with respect to such position during the subsequent checking operations, that include for example the insertion of a measuring comb 47 between the wings 48, 49 of the HSA 43, a second force lying substantially along the axis Z, or clamping force, is applied on the bearing of the HSA 43 by a floating ball 58 of a clamping device 59 (figure 6) , so as to urge suitable first surfaces 50 of the HSA 43 in abutment against suitable second surfaces 51 of the nosepiece 22 and to clamp the HSA 43 in a checking position. Once the checking operations on the HSA 43 are finished, the floating ball 58 is displaced away from the HSA 43, the piston 38 is retracted so that the coil spring 37 brings the transmission mechanism 27 back in the rest position, and the thrust pin 34 moves away from the tang 42 unlocking the HSA 43, which can be removed and replaced by a new HSA to be checked.

Hence, the reference and locking system 20 can be advantageously used in a checking system for HSA 43 of a known type, for example in an optoelectronic apparatus of the type illustrated in the patent No. EP 1029219 Bl or in the international patent application published with No. WO 2006/097445. Such an optoelectronic apparatus is shown in figure 7 and includes a clamping device 52 for the mechanical piece to be checked, detection devices 53, for example of the optoelectronic shadow casting type, that provide signals indicative of the position of at least some parts of the HSA to be checked, a processing unit 54 adapted to receive the signals of the detection devices 53 and to provide information concerning the position and/or the shape of the HSA to be checked, and rotation devices 55 and/or translation devices 56, 57 for mutually rotating and/or translating the detection device of the optoelectronic type 53 with respect to the mechanical piece to be checked.

In practice, according to the checking systems for HSAs illustrated in the patent No. EP 1029219 Bl and in the international patent application published with No. WO 2006/097445, the described reference and locking systems can be advantageously substituted by the reference and locking system 20 of the present invention. The reference and locking system 20 can be modified, without departing from the scope of the present invention. In particular, alternative embodiments of the reference and locking system according to the present invention can include component parts which have dimensions and shape differing from those of the component parts illustrated with reference to figures 3-6. For example, the hole 33 housing the thrust pin 34 can be shaped in such a way that the thrust pin 34 is arranged sloping with respect to the longitudinal direction Z. Even the end portion 39 of the thrust pin 34 contacting the tang 42 of the bearing of the HSA 43 can be differently shaped: for example, it can be semicircular shaped so as to improve the contact with the tang 42.

Moreover, the rotation pin 36 can be arranged in a position which is different from the illustrated position, provided that under the thrust applied by the pneumatic piston 38, it enables the end portion 39 of the thrust pin 34 to move along a downward arc trajectory.

Claims

1. A reference and locking system (20) for a mechanical piece (43) to be checked, comprising • a stationary part with

• a support base (21) , and

• a reference nosepiece (22) which is fixed to the support base (21) and defines a longitudinal direction (Z) , the reference nosepiece (22) including an opening (23) with reference surfaces

(40,41) adapted to cooperate with the mechanical piece (43) to be checked at a checking position; and

• a locking assembly, adapted to keep the mechanical piece (43) to be checked urged against said reference surfaces (40,41) of the reference nosepiece (22), and including a thrust device (38,45) and a transmission mechanism (27), the thrust device (38,45) being adapted to urge the transmission mechanism (27) against the mechanical piece (43) to be checked, characterized in that said transmission mechanism (27) includes a fastening portion (34) adapted to apply to the mechanical piece (43) to be checked a locking force having components lying along the longitudinal direction (Z) and along a direction (X) transversal to the longitudinal direction (Z) .

2. The reference and locking system according to claim 1, wherein said transmission mechanism (27) includes a central body (28) adapted to rotate about a direction (Y) substantially perpendicular to the longitudinal and transversal directions.

3. The reference and locking system according to claim 2, wherein said central body (28) is connected to said stationary part by means of a rotation pin (36) .

4. The reference and locking system according to claim 3, wherein said central body (28) is connected to the reference nosepiece (22) and is urged by said thrust device (38, 45) along a longitudinal direction.

5. The reference and locking system according to any one of claims 2 to 4, wherein said fastening portion (34) includes a thrust element adjustably connected to the central body (28) .

6. The reference and locking system according to claim 5, wherein said transmission mechanism (27) is substantially L-shaped.

7. The reference and locking system according to any one of the preceding claims, including a transversal urging device (37) which substantially acts along a transversal direction and is adapted to urge the transmission mechanism (27) in a rest position.

8. An optoelectronic apparatus for checking position and form deviation of a mechanical piece (43) to be checked, including

• a clamping device (52, 59) for the mechanical piece (43) to be checked;

• a detection device (53) of the optoelectronic type for providing signals indicative of the position of component parts of the mechanical piece (43) to be checked, • a processing unit (54) adapted to receive said signals of the optoelectronic detection device (53) and to provide information relating to the position and/or form deviation of the piece (43) to be checked; and

• rotation and/or translation devices (55,56,57) for mutually rotating and/or translating said detection device (53) of the optoelectronic type with respect to the mechanical piece (43) to be checked; characterized in that the apparatus further includes a reference and locking system (20) for the piece (43) to be checked according to any one of the preceding claims.

9. A method for checking dimensions and/or form deviation of a mechanical piece (43) , including the steps of

• positioning the mechanical piece (43) to be checked on a reference nosepiece (22) defining a longitudinal direction (Z) ; • generating a locking force for positioning the mechanical piece (43) in a checking position;

• generating a clamping force for clamping the mechanical piece (43) in the checking position;

• carrying out the checking of dimensions and/or form deviation of the mechanical piece (43) by means of a detection device (53) of the optoelectronic type adapted to provide signals indicative of the position of component parts of the mechanical piece (43) to be checked, said signals being adapted to be processed by a processing unit (54) ;

• removing the locking force and said clamping force; and

• removing the mechanical piece (43) , characterized in that said locking force includes components lying along both the longitudinal direction (Z) and a transversal direction (X) perpendicular to the longitudinal direction (Z) .

10. The method for checking dimensions and/or form deviation of a mechanical piece (43) according to claim

9, wherein said locking force is generated by a thrust applied substantially along the longitudinal direction

(Z) .