GB2200747A

GB2200747A - Tool identification and condition monitoring

Info

Publication number: GB2200747A
Application number: GB08630669A
Authority: GB
Inventors: Kenneth Geoffrey Swift; Robert David James
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-12-23
Filing date: 1986-12-23
Publication date: 1988-08-10
Anticipated expiration: 2006-12-23
Also published as: GB8630669D0; GB2200747B

Abstract

The invention relates to an electro-optic device, which is capable of both identifying and monitoring the condition of material processing tools such as those used in cutting and forming operations. This leads to improvements in the efficiency of automatic or computer-integrated manufacturing procedures, wherein tools are inspected on the basis of signatures derived from an optical scattering system. A laser source is used to illuminate a tool which is rotated eg in a monitoring station prior to the commencement of a machining operation. Light scattered by the tool is picked-up by a photo-detection system and the resulting signature signal is compared with a reference signature signal. <IMAGE>

Description

Improvements in Tool Identification and Condition Monitoring The invention relates to an electro-optic device, which is capable of both identifying and monitoring the condition of material processing tools such as those used in cutting and forming operations. This leads to improvements in the efficiency of automatic or computer-integrated manufacturing procedures, wherein tools are inspected on the basis of signatures derived from an optical scattering system.

When a tool has been suitably positioned it can be identified by scattered light intensities which are generated by the relative motion of the tool and the light source. The signature thus evolved uniquely identifies a particular tool and can be used to monitor its condition.

Since the signature is sensitive to only small changes in tool form such features as cutting-edge degradation can be readily detected. The amplitude and temporal features of the signatures evolved from specimen tools can be represented and stored in the memory of a computer. These representative signatures can be subsequently used as a basis for comparing signatures evolved from 'passive' tools which have been, or are to be, used in cutting or forming operations, and, furthermore, can be used to assess the condition of 'active' tools after a specified number of operations. Indeed, it is possible for critical material-removal applications to assess the condition of an active tool at discrete stages during the machining operation.The computer can be programmed to report the tool condition and arrange for substitute tools to be made available in the event of tool breakage or degradation outside pre-determined limits being detected.

The invention utilizes a conventional or directionally-coherent incident light source, such as a low power ( < lmW) He-Ne laser, from which scattered signals or signatures are generated as a result of interaction with geometric features of the tool under examination. The scattered light intensities are measured by a photo-detection system (typically photo-diodes or photo-transistors), and spatial adjustment of the photo-detection system and adjustment of the direction and/or area of the light source are provided so that a wide range of tool geometries can be accomodated.

The principle of operation is illustrated in Figure 1, where a cutting tool of the insert type is scanned as it rotates in a condition-monitoring station prior to the commencement of a machining operation. Sample signatures for a tool edge are shown in Figure 2. The top trace shows the signature representing the sharp cutting edge of an unused tool, whilst the lower trace is a signature derived from a worn cutting edge. The voltage-time plots are clearly and significantly different and can be readily processed by a microprocessor-based device.

The arrangement can be readily mounted on machine tools commonly used in industry, and the signatures evolved can be used to identify particular tools and monitor their condition during service, providing useful information for tool management and adaptive control systems. These considerations are particularly relevant to modern computer-controlled machines for the production of parts by processes such as milling, turning, grinding, punching, bending and so on. Such machines may have facilities for local tool storage in the form of turrets, racks, or magazines containing numerous separate 'passive' tools waiting to be used. It is proposed that, typically, the 'tool waiting time' should be utilised for automatic condition-monitoring in one implementation of the invention described above. Individual tools are subjected to the automatic checking procedure and, depending upon the results of this, either accepted for service or rejected. If a tool is rejected an audible and visible signal may be generated to alert a supervisor that action is required, and a 'sister' tool automatically selected as required.

Alternatively, or additionally, 'active' tools may be checked immediately prior to and following discrete stages of particularly critical material-removal operations, thereby minimising the deleterious effects of using tools in less than optimum condition.

Claims

CLAIMS:

What we claim is:1. An optical device for tool recognition and condition-monitoring based on the principle of comparison, with predetermined standards, of discrete signatures generated as a direct result of the relative motion between a conventional or directionally-coherent incident light beam with features of the tool geometry.
2. A device as described in Claim 1, which automatically checks the condition of 'passive' tools during periods when such tools are waiting in the local storage system of a machine tool.
3. A device as described in Claim 1, whereby 'active' tools are checked at discrete stages of a material-removal process.
4. A device as described in Claim 1, which forms the basis of a tool management system with automatic checking facilities remote from material processing areas.