WO2001071275A1

WO2001071275A1 - A method of calibrating a crimp measuring gauge and a standardised body for use in such method

Info

Publication number: WO2001071275A1
Application number: PCT/GB2001/001190
Authority: WO
Inventors: Anthony Stanford
Original assignee: Bespak PLC
Current assignee: Consort Medical Ltd
Priority date: 2000-03-21
Filing date: 2001-03-19
Publication date: 2001-09-27
Anticipated expiration: 2002-09-21
Also published as: GB2360590B; GB0006823D0; AU4088601A; GB2360590A

Abstract

The present invention relates to a method of calibrating a crimp measuring gauge (1) of the type comprising a housing (7), a plurality of pivotable jaws (3) circumferentially located about a longitudinal axis (Y1), collet (9) enclosing the jaws and slidable relative thereto to pivot the jaws between open and closed positions, and a longitudinally orientated telescopic member (8) which is biassed into a fully extended position. The telescopic member is operatively coupled to a display means (6) for indicating the axial displacement of the telescopic member. The method comprises the steps of inserting a standardised body (10) of known shape and size into the gauge (1) to contact and axially displace the telescopic member (8) relative to the housing (7), sliding the collet (9) so as to pivot the jaws (3) to their closed position. The standardised body is then released such that the telescopic member urges the standardised body into contact with the jaws thereby fixedly locating the standardised body both radially and longitudinally relative to the gauge. The display means is then to thereby calibrate the gauge.

Description

A METHOD OF CALIBRATING A CRIMP MEASURING GAUGE AND A STANDARDISED BODY FOR USE IN SUCH METHOD

The present invention relates to a method of calibrating a crimp measuring gauge and the provision of a standardised body for such calibration.

A popular form of dispensing apparatus for dispensing, in particular, pharmaceutical products, is a metering valve attached to a dispensing container. Such dispensing apparatus are used in particular for dispensing pharmaceutical products in the form of aerosols. One such use is in the treatment of asthmatic conditions by the delivery of a pharmaceutical product held in suspension or in solution in a volatile propellant stored in the dispensing container as an aerosol.

The metering valve is assembled with the dispensing container and retained thereon by use of a cap or ferrule which is crimped around the open neck of the dispensing container. It is important that a high quality seal is obtained between the metering valve and the dispensing container to prevent loss of propellant and product during the storage life and useable life of the dispensing apparatus. To this end an elastomeric gasket is provided at the contact surface between the metering valve and the open neck of the dispensing container. The crimping action of the ferrule around the open end of the dispensing container compresses the elastomeric gasket, forming a gas-tight seal. It is known that the degree of compression of the elastomeric gasket is an important factor in the quality of the seal between the metering valve and the dispensing apparatus. As such, it is standard practice when manufacturing such dispensing apparatus to measure the degree of crimp applied to the dispensing apparatus, that is , the degree of compression of the elastomeric gasket. It is known to use a crimp measuring gauge for this purpose. The gauge operates on the principle that the greater the degree of compression of the elastomeric gasket, i.e., the greater the crimp, the shorter the axial distance will be between an upper face of the cap or ferrule of the metering valve and a position on the neck of the crimped cap or ferrule of a set diameter.

A known crimp measuring gauge 1 is shown in Figures 1 and 2. The gauge 1 comprises a housing 7 having a number of dependant jaws 3 circumferentially located about a longitudinal axis Y¹ and which are inwardly pivotable from an open position as shown in Figure 2 to a closed position as shown in Figure 1 to engage a dispensing apparatus 30 when a collet 9 is moved axially along the jaws 3. The jaws 3 are sprung so as to be biassed into their open position. The gauge 1 also comprises a telescopic sleeve member 8 as best seen in Figure 3 which is biassed by a spring or similar into an extended position, but is retractable axially into housing 7. A display 6 is provided for displaying a measure, preferably a direct linear measurement, of the degree of retraction of the telescopic sleeve 8. In order to accurately measure the degree of compression of the elastomeric gasket by such a method it is essential to calibrate the crimp measuring gauge against a known standard.

A known standardised body 20 for use in calibrating the crimp measuring gauge 1 is shown in

Figures 2 and 3. The standardised body 20 comprises a generally cylindrical portion 21 having a flange 21 of enlarged diameter and of thickness X. The transverse faces 24, 25 of the flange 21 are perpendicular to the longitudinal axis Y² of the body 20.

In use, the standardised body 20 is inserted between the jaws 3 of the crimp measuring gauge 1 where it contacts and axially displaces the telescopic sleeve 8 relative to the housing 7. The collet 9 of the crimp measuring gauge 1 is then axially slid over the jaws 3 to pivot the jaws 3 into their closed position. The standardised body 20 is then released and the biassing force of the telescopic sleeve 8 of the crimp measuring gauge 1 urges the transverse face 24 of flange 21 of the standardised body 20 into contact with the jaws 3. as shown in Figure 3. The reading on the dial gauge 6 of the crimp measuring gauge is then read. Since the axial dimension X of the flange 21 is known, the reading may be used to calibrate the crimp measuring gauge 1.

However, in use, the applicant has discovered that this method of calibrating a crimp measuring gauge is inaccurate. As can be seen from Figure 4, when used to measure the crimp of a dispensing apparatus 30, the jaws 3 of the crimp measuring gauge 1 contact a surface of the cap or ferrule 31 or dispensing container 32 which is at an angle to a longitudinal axis Y³ of the dispensing container 32. As such, the radial positioning of the jaws 3 of the crimp measuring gauge 1 also affects the reading on the crimp measuring gauge. The known standardised body 20 is unable to calibrate for inaccuracies in the radial positioning of the jaws 3. Such inaccuracies can occur where one or more of the jaws 3 are worn or damaged or simply from manufacturing tolerances which vary from gauge to gauge. Accordingly, the present invention provides a method of calibrating a crimp measuring gauge of the type comprising a housing, a plurality of pivotable jaws circumferentially located about a longitudinal axis, a collet enclosing the jaws and slidable relative thereto to pivot the jaws between open and closed positions, and a longitudinally orientated telescopic member which is biassed into a fully extended position, the telescopic member being operatively coupled to a display means for indicating the axial displacement of the telescopic member, the method comprising the steps of inserting a standardised body of known shape and size into the gauge to contact and axially displace the telescopic member relative to the housing, sliding the collet so as to pivot the jaws to their closed position, releasing the standardised body such that the telescopic member urges the standardised body into contact with the jaws thereby fixedly locating the standardised body both radially and longitudinally relative to the gauge, and reading and/or zeroing the display means to thereby calibrate the gauge. The invention also provides a standardised body for use in the claimed method comprising a generally cylindrical body having a waisted portion.

The invention also provides apparatus for measuring crimp height comprising a gauge comprising a housing, a plurality of pivotable jaws circumferentially located about a longitudinal axis, a collet enclosing the jaws and slidable relative thereto to pivot the jaws between open and closed positions, and a longitudinally orientated telescopic member which is biassed into a fully extended position, the telescopic member being operatively coupled to a display means for indicating the axial displacement of the telescopic member; and one or more standardised bodies each comprising a generally cylindrical body having a waisted portion.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a known crimp measuring gauge being used to measure the crimp of a dispensing apparatus;

Figure 2 is a perspective view of the crimp measuring gauge of Figure 1 with a known standardised body;

Figure 3 is a cross-sectional view of a known standardised member engaged in the jaws of the crimp measuring gauge;

Figure 4 is a cross-sectional view of a standardised body according to the present invention engaged with the jaws of the crimp measuring gauge; and

Figure 5 is a cross-sectional view of the standardised body of Figure 4.

A standardised body 10 according to the present invention as shown in Figures 4 and 5 comprises a generally cylindrical body 12 having a side wall 13 with a waisted portion 11 of reduced diameter. The waisted portion 11 of the side wall 13 has a generally concavely curved surface 14 which is formed so as to accurately mirror the shape and dimensions of the neck portion of the dispensing apparatus 30 on which the calibrated gauge 1 will be used. Preferably the external dimensions of the standardised body mirror the external dimensions of the dispensing apparatus 30. However, it is only essential that the dimensions in the proximity of the neck portion are accurately mirrored. The standardised body 10 may be manufactured from any suitable material having the necessary hardness and durability, for example, hardened steel.

In use, the gauge 1 is calibrated as follows:

- The collet 9 is axially slid upwardly in the direction of the display 6 to allow the jaws 3 to spring apart into their open position; The standardised body 10 is inserted into the gauge 1 between the jaws 3 with the longitudinal axis Y¹ of the gauge 1 substantially aligned with the longitudinal axis Y² of the standardised body 10, so as to contact and axially displace the telescopic sleeve 8 relative to the housing 7; Whilst the standardised body 10 is held in position relative to the jaws 3, the collet 9 is slid axially in the direction away from the display 6 so as to pivot the jaws 3 into their closed position such that the jaws 3 are axially aligned with the waisted portion 11. The standardised body 10 is released such the biassing force of the telescopic sleeve 8 urges the standardised body 8 firmly into contact with the jaws 3. Consequently, the standardised body is retained both axially and radially relative to the gauge 1; The display is read to determine the calibration factor.

It is important to note that the point of contact between the jaws 3 and the standardised body 10 is on curved surface 14. The tangent to curved surface 14 is at an angle α to the longitudinal axis Y² of the standardised body 10. Angle is between 1 and 89 degrees. Preferably angle α is between 30 and 60 degrees. As will be understood the contact of the jaws 3 on such an inclined surface fixes the position of the standardised body 10 relative to the gauge 1 in both the radial and axial directions. The standardised body is therefore able to calibrate the gauge 1 for inconsistences in both radial and axial dimensions compared to the known standardised body 20 which can only calibrate the gauge 1 for inconsistencies in the axial dimension.

Claims

CLAIMS :

1. A method of calibrating a crimp measuring gauge of the type comprising a housing, a plurality of pivotable jaws circumferentially located about a longitudinal axis, a collet enclosing the jaws and slidable relative thereto to pivot the jaws between open and closed positions, and a longitudinally orientated telescopic member which is biassed into a fully extended position, the telescopic member being operatively coupled to a display means for indicating the axial displacement of the telescopic member, the method comprising the steps of inserting a standardised body of known shape and size into the gauge to contact and axially displace the telescopic member relative to the housing, sliding the collet so as to pivot the jaws to their closed position, releasing the standardised body such that the telescopic member urges the standardised body into contact with the jaws thereby fixedly locating the standardised body both radially and longitudinally relative to the gauge, and reading and/or zeroing the display means to thereby calibrate the gauge.

2. The method of claim 1 wherein the standardised body is urged into contact with the jaws such that the jaws contact a side wall of the standardised body.

3. The method of claim 1 or claim 2 wherein the standardised body is urged into contact with the jaws such that the jaws contact a surface of the standardised body which is inclined to the longitudinal axis at an angle other than 90 degrees.

4. The method of claim 3 wherein the standardised body is urged into contact with the jaws such that the jaws contact a surface of the standardised body which is inclined to the longitudinal axis at an angle of between 30 and 60 degrees.

5. A standardised body for use in the method of any of claims 1 to 4 comprising a generally cylindrical body having a waisted portion.

6. A standardised body as claimed in claim 5 wherein at least a portion of the surface of the waisted portion is inclined to a longitudinal axis of the standardised body at an angle of between 30 and 60 degrees.

7. A crimp measuring gauge as calibrated by the method of any of claims 1 to 4.

8. Apparatus for measuring crimp height comprising a gauge comprising a housing, a plurality of pivotable jaws circumferentially located about a longitudinal axis, a collet enclosing the jaws and slidable relative thereto to pivot the jaws between open and closed positions, and a longitudinally orientated telescopic member which is biassed into a fully extended position, the telescopic member being operatively coupled to a display means for indicating the axial displacement of the telescopic member; and one or more standardised bodies each comprising a generally cylindrical body having a waisted portion.

9. A standardised body as hereinbefore described with reference to and as shown in Figures 4 and 5 of the accompanying drawings.