Tool or tool holder

Details Tool or tool holder Tool or tool holder

1998-08-27

2001-10-02

Horabik, Michael (Department: 2735)

Communications: electrical

Continuously variable indicating

Via radiant energy beam

C340S010100, C340S010300, C342S042000, C333S150000

Reexamination Certificate

active

06297747

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a tool or tool holder with which at least one sensor operating in a contactless manner is associated functionally and spatially whose measurement signals are input to a signal processing unit for evaluation.
A known tool holder of this type (German Patent Application DE 42 38 338 A1) is provided with an observation device for a tool in order to determine the extent of wear and/or to detect breakage of a tool in a tool holder of an operating machine. The observation device has a stationary displacement sensor that can detect a dislocation or displacement. The displacement sensor is arranged spatially fixed in the supporting housing of the tool spindle. A reference surface is provided on the rotating tool spindle spaced from it. The spacing of the reference surface from the displacement sensor depends on the force occurring during operation with the tool. If this spacing changes during operation, e.g. due to a tool breaking, it is detected by the displacement sensor in a contactless manner and is fed to an associated signal processing unit in the form of a suitable signal. The stationary displacement sensor requires an energy supply for signal production. Battery supplied sensors with VHF signal transmission or with signal transmission on an infrared basis are known. These observation devices are expensive, troublesome and already have considerable disadvantages because of the required current supply for the sensors, especially those supplied with current from batteries, because of technical considerations for the batteries.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a tool or tool holder of the above-described type which requires no energy supply, in the form of batteries, in regard to its monitoring device and makes possible a measuring or controlling monitoring of the most different physical variables directly on the tool or tool holder itself during rotational motion of it in a simple and compact manner.
These objects, and others that will be made more apparent hereinafter, are attained in a tool or tool holder of the above-described kind having at least one sensor operating in a contactless manner associated functionally and spatially with the tool or tool holder, whose measurement signals are input to a signal processing unit for evaluation.
According to the invention, the at least one sensor is a surface acoustic wave sensor operating according to surface acoustic wave principles whose measurement signals are picked off or interrogated from a remote location in a contactless manner.
Further advantageous embodiments of the invention are claimed in the dependent claims appended hereinbelow.
Surface acoustic wave sensors are known (EP 619 906 B1) electro-acoustic components. The characterizing feature of the invention, in contrast, is to provide special tools or tool holders with this type of surface acoustic wave sensor and not only use its properties of measurement and observation, but, as needed, to equip it for a controlling monitoring and to equip the tool or tool holder with it. A contactless monitoring of the widest variety of manufacturing processes in operating machines is possible using the invention by means of telemetric signal transmission and passive signal coding and reflection. Both analog variables, such as force, torque, displacement, temperature, pressure or the like, and binary signal states, can be monitored to determine, e.g. the signal state “position reached” or “threshold exceeded”. The stability of processes may be controlled and a protocol established by detection of the above-named variables. The operator, the operating machine, the workpiece and/or the tool can be protected by an emergency stop in case of danger. The wear on the tool can be measured with geometrically predetermined knife edges and the tool can be used until the end of its service life. An impairment of the product quality and undesired idle time can be largely avoided. The at least one surface acoustic wave sensor is attached to the tool or the tool holder or an other part, e.g. an operating machine, which performs a process-dependent action, e.g. molding, during the working process. The at least one surface acoustic wave sensor can be interrogated, i.e. can transmit signals, by radio waves without wires. It operates maintenance-free after its installation, whereby no additional energy source, e.g. battery, is required. The one or more surface acoustic wave sensors may be interrogated in a very short time and allow a timely resolution of even very rapid mechanical processes. The measured signals (sensor signals) contain information regarding the time behavior of a possible deformation cause and thus about the quality, e.g., of a tool, of the operating process. The at least one surface acoustic wave sensor is universally useable. Since no additional electronic units are required on the sensor-side for a possible signal processing, substantial space, weight and cost savings result. Furthermore the support of the at least one surface acoustic wave sensor, also e.g. the tool, the tool holder or another part, are not noticeably weakened by introducing larger holes or cavities for support of the at least one surface acoustic wave sensor which would otherwise be required for the additional electronic units. Also the invention has a universal applicability because of that. The at least one surface acoustic wave sensor can, e.g., be attached to the upper end of a shaft in a known manner. The particular manner of mounting depends on the shaft. Previously required batteries with all their associated problems are eliminated because of the passive operation that does not require current supply. The arrangement may be formed so that the at least one surface acoustic wave sensor is protected against outside influences, e.g. against liquids and cooling agents. In case of an inner cooling supply through the shaft or the like, this cooling supply can be formed according to the specifications, without considering the arrangement of the at least one surface acoustic wave sensor. Above all it is to be understood that any of the most different types of tools, components or machine parts, e.g. in the form of a detecting tool (measuring tool), measuring tool, machining or cutting tool, clamping or gripping tool, end-of-travel tool or the like. The terms “tool” or “work tool” are to be understood in the widest sense. In the case of the end-of-travel device an end position observation of parts that are moveable relative to each other for a monitoring controller, especially machine parts, takes place by means of a surface acoustic wave sensor acting as a position structure.
Further features and advantages of the invention are described in the following description.


REFERENCES:
patent: 4697115 (1987-09-01), Mitsutsuka
patent: 4748364 (1988-05-01), Mitsutsuka
patent: 5287035 (1994-02-01), Carroll
patent: 5365207 (1994-11-01), Borras
patent: 5563581 (1996-10-01), Kats
patent: 5731516 (1998-03-01), Handfield
patent: 5742237 (1998-04-01), Bledsoe
patent: 6107910 (2000-08-01), Nysen
patent: 6144332 (2000-11-01), Reindl
patent: 42 38 338 A1 (1994-05-01), None
patent: 43 14 235 A1 (1994-11-01), None
patent: 0 619 906 (1994-10-01), None

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