JP2005189039A - Dynamic balance testing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dynamic balance testing machine capable of measuring a work of assembled rotation body with high precision. <P>SOLUTION: A boat-shaped mount 3 for supporting the work W of assembled rotation body is placed on a base 1 through a piezoelectric plastic sheet 2. The piezoelectric plastic sheet 2 is formed with electric film electrodes on both the sides of the plastic PVDF sheet material with piezoelectric effect. Because the vertical force from the mount 3 supporting the work of the assembled rotation boy is distributed on the whole region of the piezoelectric plastic sheet 2, the load per unit area is small, therefore, the durability of the dynamic balance testing machine can be improved. Because the system in which the mount 3 is suspended with springs is not adopted, the torsional vibration is never generated and the movement of the rotating shaft of the work W is never generated, and the vibration except that caused by imbalance can be inhibited, therefore, the precision of measurement also improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dynamic balance testing machine that measures unbalance of a work having a rotating body (hereinafter referred to as an assembly rotating body work) that rotates by applying electric power or power from the outside.

  In conventional dynamic balance testing machines, rotating assembly works such as motors, turbochargers, and torque converters are installed on a boat-type platform, and the boat-type platform is suspended and supported by an elastic support member such as a leaf spring provided on the base. doing. Then, the assembly rotating body workpiece is rotated and driven by applying power or power to the assembly rotating body, and the unbalanced amount of the assembly rotating body workpiece is detected by detecting the horizontal vibration of the mounting frame at that time with a detector. (For example, Patent Document 1).

  As the detector, a moving coil type vibration detector is generally used. The coil of the detector is provided on the base, and the movable core rod that slides inside the coil is fixed on the gantry side. In some cases, piezoelectric ceramics may be used instead of the moving coil type vibration detector. In that case, the unbalanced amount of the assembly rotating body work is detected by pressing a bar that vibrates in the horizontal direction integrally with the gantry against the piezoelectric ceramic and distorting it, and detecting the polarization voltage generated at that time. .

JP 11-295178 A

  In a conventional dynamic balance tester that detects horizontal vibration of a suspended boat-type gantry, the gantry itself twists depending on the unbalanced state of the assembled rotating body work, resulting in twisting of the suspension spring. To do. If the spring is twisted, the spring constant apparently differs, which adversely affects measurement accuracy. In addition, since the rotating shaft moves due to the torsional vibration of the gantry, vibrations other than the vibration caused by the unbalance of the assembly rotating body work are generated, which adversely affects the measurement accuracy.

(1) A dynamic balance testing machine according to claim 1 is provided between a base for supporting the assembly rotary body work, a base for supporting the base, the base and the base, and the base from the assembly rotary body work. A detecting means for detecting a vertical force acting via the detecting means; and a calculating means for calculating an unbalanced amount of the assembly rotating body work based on the vertical force detected by the detecting means. .
(2) The invention according to claim 2 is the dynamic balance testing machine according to claim 1, wherein the detection means is a thin plate-like piezoelectric element extending in the horizontal direction, and the vertical force from the gantry is a thin plate-like piezoelectric device. A force in the vertical direction is detected by being distributed and energized over the entire region of the element.
(3) The invention according to claim 3 is the dynamic balance testing machine according to claim 2, wherein the thin plate-like piezoelectric element is formed of a piezoelectric plastic sheet.

  According to the present invention, since the vertical force acting from the assembly rotating body work supported on the gantry is detected and the unbalance amount is calculated, it is possible to prevent occurrence of torsional motion of the gantry and to measure The accuracy can be improved.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of a dynamic balance testing machine according to the present invention. In FIG. 1, reference numeral 1 denotes a base of a dynamic balance testing machine. Thin plate-shaped piezoelectric plastic sheets (force detectors) 2 are respectively bonded to both ends of the upper surface of the base 1, and on the piezoelectric plastic sheet 2. The gantry 3 that supports the assembly rotating body workpiece W is bonded. Such a gantry is usually called a boat-shaped gantry. The assembly rotating body workpiece W is, for example, an electric motor, and can be fixedly supported on the gantry 3 with a bolt or the like.

  The piezoelectric plastic sheet 2 has a sheet shape, and is formed by forming electrodes made of a metal film on both surfaces of a plastic PVDF (polyvinylidene fluoride) sheet material having a piezoelectric effect. The piezoelectric plastic sheet 2 has a thickness of several tens of μm to several hundreds of μm, is rich in flexibility, and has excellent impact resistance. Moreover, it has a high voltage output characteristic (mechanical-> electrical conversion) 10 times or more compared with piezoelectric ceramics.

  When the assembly rotating body workpiece W is placed on the gantry 3, a vertically downward force acts on the piezoelectric plastic sheet 2 via the gantry 3, and a polarization voltage corresponding to the magnitude of the force is generated. That is, the piezoelectric plastic sheet 2 functions as a force detector that detects a vertical force from the gantry 3.

  When electric power is applied to the assembly rotating body workpiece W to rotate the built-in rotary shaft AX, vibration due to the imbalance of the assembly rotation body workpiece W is generated, and the force applied to each piezoelectric plastic sheet 2 in the vertical direction changes. To do. And the vibration of the assembly rotary body workpiece | work W is detectable by detecting the change of the polarization voltage at that time.

  As shown in FIG. 2, the polarization voltage signal output from the piezoelectric plastic sheet 2 is amplified by an amplifier 21 provided in the arithmetic unit 20 of the dynamic balance tester and then input to the arithmetic circuit 22. The arithmetic circuit 22 calculates the unbalance amount of the assembly rotating body workpiece W based on each input polarization voltage signal. The unbalance amount is calculated for each piezoelectric plastic sheet 2. The calculated unbalance amount is displayed on the display 23 of the control unit.

Since the surface pressure is reduced by increasing the area of the piezoelectric plastic sheet 2, no problem occurs even if a large force or an impact is applied to the piezoelectric plastic sheet 2. Therefore, the piezoelectric element can be used not only for a small assembly rotating body work but also for a dynamic balance testing machine for inspecting a large assembly rotating body work.

  As shown in FIG. 3, when a horizontal force is applied to the gantry 3 due to the rotation of the assembly rotating body workpiece W, the area of the piezoelectric plastic sheet 2 is relatively large. Acts, and a tensile force acts on the right region of the piezoelectric plastic sheet 2. Therefore, the polarization voltage between these regions has a reverse polarity, and the piezoelectric plastic sheet 2 as a whole cancels and becomes almost zero. As a result, the vertical vibration can be accurately measured without being affected by the horizontal vibration.

The dynamic balance testing machine of the present embodiment can provide the following effects.
(1) In the dynamic balance testing machine according to the present embodiment, since the piezoelectric plastic sheet 2 is used, the influence of magnetism can be removed. Further, since the gantry 3 that supports the assembly rotating body work W is directly provided on the piezoelectric plastic sheet 2, a preload is automatically applied to the piezoelectric plastic sheet 2 depending on the weight of the gantry 3 and the assembly rotating body work W. ing. Therefore, the conventional preload adjustment is no longer necessary. Further, the preload does not change or the preload is not applied during the vertical vibration of the gantry 3.

(2) Since the sheet-like piezoelectric plastic sheet 2 having a large area is used, the surface pressure is reduced, and the piezoelectric plastic sheet 2 is cracked even if a large force is applied to the gantry 3 or an impact is applied. Therefore, the durability of the dynamic balance testing machine can be improved. Further, even if a horizontal force is applied to the piezoelectric plastic sheet 2 from the gantry 3, it is difficult to generate a total polarization voltage. For example, when a dynamic balance testing machine is installed on a work desk, the influence of horizontal vibration applied to the work desk is great. Therefore, it is possible to accurately measure the vertical vibration without being affected by the horizontal vibration. In particular, when a plastic PVDF sheet material having a piezoelectric effect is used as the piezoelectric plastic sheet 2, it is rich in flexibility and excellent in impact resistance, so that a further effect can be obtained.

(3) Since the gantry 3 is directly attached to the piezoelectric plastic sheet 2 and unbalanced vibration of the assembly rotating body work W is detected as a force applied to the gantry 3, the center axis of the rotating assembly rotating body W is moved. Is no longer affected by the gyro effect. As a result, the unbalance can be accurately measured.

(4) Since the gantry 3 is mounted directly on the piezoelectric plastic sheet 2 without adopting a method of suspending the boat-shaped gantry with a spring, calculation for selecting a leaf spring, an actual machine test, etc. are not required. .

(5) In the case of the conventional spring-suspended structure, the resonance frequency of the boat-type gantry is relatively low. In the case of a soft type balancer, several Hz to several tens Hz, and in the case of a hard type balancer, several tens Hz to several hundred Hz. become. For this reason, when the rotational frequency of the assembly rotating body workpiece W coincides with the resonance point of the boat-shaped frame or is a relatively close frequency, normal measurement cannot be performed due to resonance. Furthermore, in the case of the assembly rotating body workpiece W having a large unbalance, there is a disadvantage that a very large vibration is generated when the rotation frequency approaches the resonance frequency of the boat-type frame. There is also a disadvantage that the resonance signal of the boat-shaped gantry becomes much larger than the unbalanced signal. However, the dynamic balance testing machine according to the present embodiment does not employ a suspension structure such as a spring, and the assembly rotating body work W is directly placed on the laminated piezoelectric element, so that the resonance frequency of the gantry 3s is caused by an unbalance. It becomes higher than vibration, and the problem of abnormal vibration due to resonance as in the prior art does not occur.

In the above-described dynamic balance testing machine, the piezoelectric plastic sheet 2 is bonded to the base 1 and the gantry 3 but may be fixed using bolts. Further, although the sheet-like piezoelectric plastic PVDF is used as the piezoelectric plastic sheet 2, a piezoelectric element such as lead zirconate titanate (PZT) or barium titanate (BaTiO ₃ ) may be used. FIG. 4 shows an example in which a force detector 2A formed by laminating thin plate piezoelectric elements is used. When the piezoelectric element is formed into a thin plate shape, the size is set to about “1/10000 <(thickness) / (length of one side) <1/10” when a square shape is considered.

  In the correspondence between the embodiment described above and the elements of the claims, the piezoelectric plastic sheet 2, the force detector 2A are detection means, the piezoelectric plastic sheet 2 is a thin plate-like piezoelectric element, and the arithmetic unit 20 is an arithmetic means. Constitute. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

It is a figure which shows the structure of the dynamic balance testing machine by this invention. (A) is a top view. (B) is a front view The block diagram of the unbalance calculation apparatus by the dynamic balance testing machine by this invention The figure explaining the case where the force of a horizontal direction acts on the mount frame 3 The figure which shows the other example of a structure of the dynamic balance testing machine by this invention.

Explanation of symbols

1: base 2: piezoelectric plastic sheet 3: mount 20: arithmetic unit 21: amplifier 22: arithmetic circuit 23: indicator W: work

Claims (3)

A stand for supporting the assembly rotating body work;
A base for supporting the mount;
A detecting means that is disposed between the base and the gantry and detects a vertical force acting via the gantry from the assembly rotating body workpiece;
A dynamic balance testing machine comprising: a calculation means for calculating an unbalance amount of the assembly rotating body work based on a vertical force detected by the detection means. In the dynamic balance testing machine according to claim 1,
The detection means is a thin plate-shaped piezoelectric element spread in the horizontal direction, and the vertical force from the gantry is distributed and urged over the entire area of the thin plate-shaped piezoelectric element, thereby generating the vertical force. A dynamic balance testing machine characterized by detecting. In the dynamic balance testing machine according to claim 2,
A dynamic balance testing machine characterized in that the thin plate-like piezoelectric element is composed of a piezoelectric plastic sheet.

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