250MPa calendar force, 150MPa verification point when the step-up is 148MPa, when the buck is 149MPa, please tell me how to calculate the value of error, return error is how to count? Thank you
The pressure gauge common breakdown has following four points:1, the needle does not move. That is, when the pressure is raised, the indicator of the pressure gauge does not move.Cause analysis: Cock cock, not open; pressure gauge connection pipe or water pipe blockage; the pointer and the central shaft is loose or pointer stuck.2, pointer jitter.Cause analysis: hairspring damage; plug or trap local channel is blocked; both ends of a center shaft bending, two ends of the shaft rotation is not concentric.3, the pointer can not return to zero when there is no pressure.Analysis of reasons: spring tube permanent deformation, loss of flexibility; pointer and center axis loose or pointer stuck; plug, pressure gauge connecting pipe or water retaining pipe channel blocked.4 、 the instructions are incorrect and exceed the allowable error.Cause analysis: mainly due to the spring tube due to high temperature and overload or excessive deformation; gear wear loose; balance disorder; plug leakage.
According to JJG52-1999, Bourdon tube, general pressure gauge, pressure vacuum gauge and vacuum gauge, 5.3.3.5, return error:For the same test point, the difference between the indication value after tapping the watch case at the step-up (or step-down) and the buck (or boost) testThe return error is the absolute value
Pressure meter return error: under the same conditions, the measured value is constant, the measuring instrument travel direction is different, the absolute value of the difference of its indication value. Note: return error is also called lag error."The return error" and "dead zone": JJF1001 "general terms and definitions for measurement", the term "no return error", but in 7.13 another definition of the term "dead zone" to describe "causing maximum variable interval dynamic measuring instrument in response to changing incentives". Therefore, return error is an index to measure the response characteristics of equipment".Does the return error accumulate? Take the positive and negative rotation of the motor as an example, the return error of the transmission mechanism should not be accumulated once and for all. In other words, back and forth movement many times, return error or fixed interval, does not increase.Application in the motor: the motor itself is no return error, how much encoder reads, how many pulses the stepper motor turns, and the servo system is usually higher than the stepper motor accuracy. The return error is generated by the drive mechanism, such as the screw rod connected on the output shaft of the motor. Therefore, the servo system can accurately control the motor, can't handle the return error. Therefore, the zero bit switch can eliminate zero return error in the course of motion, in addition to the zero power seeking of the incremental encoder. Even if the absolute encoder does not require power on and zero, the photoelectric switch can also be used to eliminate the return error. When there is no return error in the direction of return, it is necessary to set a zero position switch at both ends, so that the motor is backward to zero in this direction, and then the zero is used to measure the movement displacement.
