GB2041521A

GB2041521A - A device for detecting a burr, on a working surface

Info

Publication number: GB2041521A
Application number: GB7903269A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-01-30
Filing date: 1979-01-30
Publication date: 1980-09-10
Also published as: GB2041521B

Abstract

A device for detecting a burr on a slip gauge has a frame (5) having a weighted bottom (6) cushioned upon rubber feet (7) and an open walled upper portion (8) housing a transducer comprising a pick-up (9) and stylus (10) over which is supported a sounding element (12) consisting of a grooved tungsten carbide plate (13). The transducer is connected via an amplifier to a loudspeaker or oscilloscope. The slip gauge is checked by sliding its working surface across the sounding element so that, if a burr is present, an intermittent audible slapping sound will be emitted from the loudspeaker. <IMAGE>

Description

SPECIFICATION A device for detecting a burr on a working surface This invention relates to a device for detecting a burr on a working surface of a precision instrument such as, for example, a working surface on a slip gauge.

Slip gauges, or gauge blocks as they are sometimes called, are rectangular blocks, usually of 1% carbon steel, having two opposed working surfaces which are ground and lapped so as to provide a very accurate unit of measurement between the faces. The slip gauges are provided in a boxed set of various different sizes of a particular grade and are used when a greater accuracy is required than can be achieved with a micrometer: there are usually four different grades of accuracy available, the unit of measurement between the working faces being accurate to 10, 5, 3 or 2 millionths of an inch. In use the slip gauges are wrung together to form a composite unit of measurement of the desired value, the adjacent slip gauges being held together simply by a surface adhesion caused by intermolecular attraction between the two highly lapped surfaces.

However, when using slip gauges, it will be understood that the working surfaces must be kept in perfect condition otherwise the accuracy is lost; for example, a minute scratch will produce side burrs of several millionths of an inch, or, if a slip gauge is dropped, a peaked burr will be produced on the edge. Nevertheless, these burrs, although significantly affecting the fine accuracy, may not be readily apparent to the user. Therefore, in order to ensure that the accuracy of the working surfaces is maintained, the slip gauges are regularly checked and reground where necessary.

However, at present, usually it is the practice to regrind the working surfaces to another accurate unit of measurement rather than risk the possibility of the existance of an undetected burr. Clearly, this means that many slip gauges are reground unnecessarily.

Accordingly an object of this invention is to provide a device for detecting small burrs on the working surfaces of precision instruments.

Therefore, according to the present invention a device for detecting burrs on a working surface of a precision instrument comprises a sounding element having a substantially planar surface with at least one groove formed therein, the working surface to be checked in use being moved across said substantially planar surface, a transducer arranged to be associated with either the sounding element or the working surface so as to emit impulses corresponding to any vibrations set up by the movement of the working surface across the substantially planar surface, an amplifier connected to the transducer, and means, connected to the output of the amplifier for converting the signals received from the amplifier into audible sound.

Preferably the sounding element comprises a plurality of lands and grooves so that a vibration is set up every time a burr on the working surface to be checked is aligned with a groove. The lands and grooves may be parallel, the lands being made of a harder material than the surface being checked, eg, in the case of checking slip gauges, tungsten carbide lands may be used.

The transducer may comprise a pick-up and stylus associated with either the sounding element or the working surface so that burrs on the working surface will set up vibrations in the stylus which are then converted to electrical signals and passed to the amplifier.

Alternatively the transducer may comprise a microphone such as a piezo-electric, pressure responsive microphone which will transmit to the amplifier any vibration set up in the part with which it is associated.

Preferably the transducer is associated with the sounding element rather than the working surface being checked since this arrangement avoids the necessity of resetting the transducer for each respective working surface.

The means for converting the signals received from the amplifier into audible sound preferably comprises a conventional loudspeaker.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows, in exaggerated form, the burrs caused by a scratch on the working surface of a slip gauge; Figure 2 shows, in exaggerated form, the effect of a burr on a composite unit of measurement formed from two slip gauges; Figure 3 shows, in perspective, one form of device for detecting burrs in accordance with the present invention; and Figures 4a and 4b illustrate, in exaggerate form, the effect of moving a working surface having a burr thereon across the sounding element.

In Figs. 1 and 2 of the drawings a slip gauge has opposed working surfaces 1 and 2 and, in Fig. 1, the working surface 1 is shown as having a scratch 3. The scratch 3 forms side burrs 4 which in use will impair the accuracy of a composite measurement using two or more slip gauges as shown in Fig. 2.

Fig. 3 shows a preferred device for detecting such burrs and it comprises a frame 5 having a weighted bottom 6 cushioned upon rubber feet 7, and an open walled upper portion 8. The upper portion 8, substantially centrally thereof, is provided with a transducer comprising a pick-up 9, having a stylus 10.

The transducer is supported on an adjustable mounting 20. Also disposed within the upper portion 8 are three projecting studs 11 which serve as supports for a sounding element 1 2 which is removably received therein.

The sounding element 12 consists of a tungsten carbide plate 1 3 secured in a wooden supporting block 14: the block 14 resting on the projecting studs 11. The tungsten carbide plate 1 3 has a plurality of parallel, upstanding, spaced lands 1 5 with grooves 1 6 therebetween. The top surfaces of the lands 1 5 are highly ground and polished and substantially coplanar. When received in the upper portion 8, the sounding element 1 2 is locked in position by manipulation of a plurality of locking studs 1 7 which engage with the wooden block 14.

Although not shown in the drawings the device also includes a conventional loudspeaker which is connected, via an amplifier, to the output 1 8 of the pick-up transducer.

In use the sounding element 1 2 is positioned in the upper portion 8 of the frame and the transducer adjusted so that the stylus 10 is in engagement with the underside of the plate 1 3. The working surface to be checked is then slid across the sounding element and, if a burr is present, an intermittent slapping sound will be audible from the loudspeaker as the stylus reacts to the vibrations set up by the burr riding up and down as it passes over the parallel lands and grooves: this can be seen clearly from Figs. 4a and 4b. If no burr is present sound will be produced but it should be a smooth sound.

Although the device of the present invention is particularly designed for use with slip gauges it will be understood that the working surface of any precision instrument may be checked. Moreover although the lands and grooves on the sounding element are prefera bly parallel and perpendicular to the axis of the element they may be arranged in any suitable disposition.

As described above the preferred form of the invention incorporates an audible burr indicating means. However, it will be understood that, if for example the checking takes place in a noisy workshop, the audible burr indicating means may not be satisfactory.

Therefore as an alternative it is proposed to have a visual indicating means such as a cathode ray tube, acting in response to the strength of the vibrations.

Moreover, if desired, the visual indicating means may be calibrated according to the strength of the vibrations so as to provide a record of the size of each burr detected.

Therefore according to another aspect of the invention a device for detecting burrs on a working surface of a precision instrument comprises a sounding element having a ridged surface over which, in use, the working surface to be checked is moved, a transducer arranged to be associated with either the sounding element or the working surface so as to emit impulses corresponding to any vibrations set up by the movement of the working surface as it is moved over the ridged surface of the sounding element, and indicating means connected to the transducer into a visual display or audible sound.

Claims

1. A device for detecting burrs on a working surface of a precision instrument comprising a sounding element having a ridged surface over which, in use, the working surface to be checked is moved, a transducer arranged to be associated with either the sounding element or the working surface so as to emit impulses corresponding to any vibrations set up by the movement of the working surface as it is moved over the ridged surface of the sounding element, and indicating means connected to the transducer for converting the impulses received from the transducer into a visual display or audible sound.

2. A device for detecting burrs on a working surface of a precision instrument comprising a sounding element having a substantially planar surface with at least one groove formed therein, the working surface to be checked in use being moved across said substantially planar surface, a transducer arranged to be associated with either the sounding element or the working surface so as to emit impulses corresponding to any vibrations set up by the movement of the working surface across the substantially planar surface, an amplifier connected to the transducer, and means, connected to the output of the amplifier for converting the signals received from the amplifier into audible sound.

3. A device according to claim 1 or 2 wherein the sounding element comprises a plurality of lands and grooves so that a vibration is set up every time a burr on the working surface to be checked is aligned with a groove.

4. A device according to claim 3 wherein the lands and grooves are parallel, the lands being made of a harder material than the surface being checked.

5. A device according to any one of the preceding claims wherein the transducer comprises a pick-up and stylus associated with either the sounding element or the working surface so that burrs on the working surface will set up vibrations in the stylus which are then converted to electrical signals.

6. A device according to any one of claims 1 to 4 wherein the transducer comprises a microphone such as a piezo-electric, pressure responsive microphone which will transmit any vibrations set up in the part with which it is associated.

7. A device according to claim 5 or 6 wherein the transducer is associated with the sounding element.

8. A device according to claim 1 wherein the indicating means is visual and comprises a cathode ray tube acting in response to the strength of the vibration.

9. A device according to claim 1 wherein the indicating means is audible and comprises an amplifier and a loudspeaker.

1 0. A device according to claim 2 wherein the means for converting the signals received from the amplifier into audible sound comprises a loudspeaker.

11. A device for detecting burrs on a working surface of a precision instrument substantially as hereinbefore described with reference to the accompanying drawings.