Electricity: measuring and testing – Magnetic – Combined
Patent
1986-10-07
1989-02-14
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
Combined
7386251, 324205, 324262, G01R 3312, G01L 100
Patent
active
048049140
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
The invention relates to machine tool engineering, and in particular, it deals with methods for determining force characteristic of a device for magnetically holding workpieces.
STATE OF THE ART
The main characteristic of devices for magnetically holding workpieces is a force characteristic, i.e., distribution of the force of attraction of workpieces over the surface of a plate which makes it possible to evaluate capabilities of the device and quality of its manufacture.
It is important to reveal, in such distribution of force, values and zones of minimum attraction forces to be used in setting forth machining conditions for workpieces being held, and also the character of distribution which determines magnetic deformations of parts, and hence, influences accuracy of their machining.
The force tests are the main method for evaluating quality of a jig that makes it possible to detect flaws of component parts and assembly.
Widely known in the art is a method for determining force characteristic of devices for magnetically holding workpieces, comprising: surface with the device turned-off; a dynamometer in the direction at right angles to the surface of the device and recording the stripping force;
Stripping off the test sample is effected in a succession along a test line at a pre-set spacing. Thus, a maximum advance where a user can get trustworthy and sufficiently detailed information on the distribution of the forces of attraction along the surface of the device is about 1/7 of the test diameter.
The test results are plotted in the form of a broken line, numbers of control points being plotted on the abscissa and values of attraction forces at these points being plotted on the ordinates, and the resultant points are interconnected by a broken line.
It will be apparent that the shorter the distance between the control points being interconnected, the closer is the resultant broken line to the actual force characteristic of the device. At the same time, an increase in the number of control points results in a substantial increase in the test time.
All preparatory and measurement operations connected with a force control at one point of the plate take about three minutes. Bearing in mind that such control should be effected at more than 170 points for an electromagnetic plate of a size 320.times.1250 mm, it will be understood that the control time of such a device is commensurable with the time needed for its manufacture (the force test is carried out for over 8 hours). It is obvious that such tests will take a much longer time for plates of larger size as 630.times.2500 mm.
At the same time, even such long tests will not always allow actual values of minimum attraction forces to be revealed because of their discontinuous nature as control points may not coincide with zones of application of minimum forces of attraction.
Therefore, the prior art methods for controlling force characteristic of holding devices take a long time and do not make it possible to obtain a comprehensive force characteristic of the device. It should be noted that reducing the test time (reduction of the number of control points) results in a lower reliability of the test results and, vice versa, an improvement of reliability of the control results (an increase in the number of control points) calls for a substantial increase in the test time.
SUMMARY OF THE INVENTION
The invention is based on the problem of providing a method for determining force characteristic of devices for magnetically holding workpieces which allows a full force characteristic of the device to be obtained with a short test time.
This problem is solved by a method for determining force characteristic of a device for magnetically holding workpieces installed on a top plate of the device, comprising connecting a workpiece cooperating with a source of magnetic field of the device to a force indicator and causing the workpieces to move along a test line, according to the invention, the source of magnetic field is held permanently energized duri
REFERENCES:
patent: 4465975 (1984-08-01), Porter
O.Ya. Konstantinov "Raschet i konstruirovanie magnitnykh i elektromagnitnykh prisposobleny", 1967, Mashinostroenie (Leningrad), cf. 80-83.
NIIMash, seria 0-1 Stankostroenie, 1982 (Moskva): O. F. Poltavets et al, "Metody i sredstva kontrolya tochnosti parametrov korpusnykh detaley", cf. pp. 32, 33.
Entsiklopedia sovremennoi tekhniki. Avtomatizatsia proizvodstva i promyshlennaya elektronika, vol. I, 1962, Sovetskaya Entsiklopedia (Moskva), cf. pp. 281-282.
Barab-Tarle Matus E.
Khinkus Alexandr S.
Rashkovich Mikhail P.
Soifer Romen D.
Trostanovsky Boris A.
Odesskoe skb Spetsialnykh Stankov
Strecker Gerard R.
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