1.Overview

Angular contact (thrust) spherical plain bearings have large load capacity and impact resistance due to large spherical sliding contact area and large inclination angle, and have corrosion resistance, wear resistance, self-aligning, good lubrication or self-lubricating type without lubrication Therefore, it is widely used in low-speed swing motion, tilt motion and rotary motion, such as engineering hydraulic cylinders, forging machine tools, engineering machinery, automation equipment, automobile shock absorbers, water conservancy machinery, etc.

Angular contact spherical plain bearings and thrust spherical plain bearings are the leading products of two of the six series of our company, with a wide range of product models and mass production every month. The assembly height of the product (the H value in Figure 3) is an important technical parameter, especially the self-lubricating type, which is a full inspection item during the final inspection of the finished product. Therefore, how to improve the measurement accuracy and measurement efficiency and reduce the labor intensity of the inspection personnel has become an urgent problem for enterprises to ensure the quality of mass-produced products and meet market demand.

2. Original measurement methods and existing problems

Since the working sliding surfaces of the inner and outer rings of the angular contact (thrust) spherical plain bearing are less hemispherical, the outer ring and the inner ring can swing each other, and the commonly used height measuring instrument cannot measure this parameter. There are mainly two kinds of original detection methods: the first is to use the mandrel method to measure, as shown in Figure 1. This inspection method has four defects: (1) Each model needs to be equipped with a mandrel with the same size as the inner diameter of the shaft ring; (2) The mandrel and the shaft ring are clearance fit, the gap is too large, and the measurement value error is large; If it is too small, it is not easy to install and unload the mandrel, and it is difficult to measure; (3) When testing large-scale and large-scale products, the physical requirements of the inspectors are high during the process of loading and unloading the mandrel, and the labor intensity is high. A little carelessness may crush your fingers; (4) The mandrel must be repeatedly loaded and unloaded for each set of measurements, and the detection efficiency is low. The second is measured with a micrometer, as shown in (Figure 2). Use two micrometers to measure at the symmetrical positions of the product. During the measurement, the measured value of the micrometer should be adjusted repeatedly until the measured value of the two micrometers is consistent, and the measured value at this time is the assembly height. The defects of this inspection method are: (1) The two micrometers have to be adjusted many times to obtain the measurement value, which is cumbersome and inefficient, and is not suitable for batch measurement; (2) It requires certain measurement skills to obtain accurate measurement values. The defects of the above two measurement methods are mainly caused by overcoming the mutual swing of the outer ring and the inner ring during the measurement. Therefore, how to quickly ensure that the two measurement datum planes are parallel to each other during the measurement has become the focus and core of the design. To this end, I designed this angular contact (thrust) spherical plain bearing assembly height measuring instrument to solve this problem.

3. Measuring principle of the measuring instrument

Since the angular contact (thrust) spherical plain bearing has the characteristics of concentric inner and outer ring ball diameters and self-aligning, and the surface roughness of the spherical surface is less than Ra0.8, so after applying a small pressure F to the shaft ring, as shown in Figure 3, The datum plane of the shaft washer can be made parallel to the datum plane of the seat ring, and the H value measured at this time is the assembly height of the bearing.

4. The main structure of the measuring instrument

In order to realize the measurement principle shown in Figure 3, it can be realized by the measurement mechanism shown in Figure 4. The instrument is mainly composed of the following parts: basic device (table, column, cantilever, V-shaped positioning fork, anti-wear gasket, etc.); lifting transmission system (threaded knob, trapezoidal threaded shaft, pressure plate); measuring system (indicating instrument frame, precision 0.01 indicating instrument); anti-overload system (anti-overload bushing, handle, etc.); V-shaped positioning fork (adjustable position, positioning the bearing under test). In order to meet the detection of bearings of different types and specifications in the production process, the measuring instrument is designed to cover as many types as possible, ranging from GAC25 to GAC150, GX10 to GX120 (nominal outer diameter of bearing seat ring Φ30 to Φ230mm) can be measured.

5 Design points

(1) This measuring instrument is designed using the characteristics that the inner and outer rings of the bearing can swing each other and the ball diameters are concentric and can be automatically adjusted. Whether the pressure plate and the worktable are parallel is an important factor affecting the measurement accuracy. In order to ensure the measurement accuracy, in addition to the rigidity and shape and position tolerances of the relevant components of the basic device, the matching clearance between the outer diameter of the trapezoidal threaded shaft and the cantilever aperture must be precisely guided under the premise that the trapezoidal threaded shaft can move up and down flexibly ( The clearance fit is controlled at 0.02-0.04mm) to eliminate the influence of the clearance on the measurement accuracy.

(2) En el sistema de transmisión de elevación, la rosca trapezoidal (paso 20, paso 5) con buena artesanía, alta resistencia de la rosca y buena neutralidad se utiliza para la transmisión de carga y transmisión de carrera. El mecanismo de elevación puede realizar un movimiento de elevación rápido, mejorar la eficiencia del trabajo y reducir la intensidad del trabajo; Al mismo tiempo, para evitar una carga excesiva en el rodamiento de medición y causar la deformación del instrumento de medición y el producto, un conjunto de sistema anti-sobrecarga está especialmente diseñado para protección contra sobrecarga, como se muestra en la Figura 5. El mango impulsa el buje anti-sobrecarga y la bola de acero para girar, y la perilla roscada gira bajo la presión de la bola de acero. Cuando la carga es demasiado grande, la bola de acero se levanta y el buje antisobrecarga se desliza y gira, desempeñando así un papel de protección contra sobrecarga.

(3) Dado que el plano de no referencia de la arandela del eje del cojinete de contacto angular terminado y el plano de referencia del anillo de asiento están en el mismo plano, como se muestra en la Figura 6, antes de aplanar la arandela del eje, el punto A será más bajo que el plano de referencia, por lo que es necesario utilizar un soporte durante la medición. La altura de montaje solo puede medirse por la altura del bloque de la pista de rodadura. Con este fin, diseñamos dos bloques de soporte móviles en el banco de trabajo para soportar los rodamientos probados. Para las chumaceras esféricas de empuje, dado que la cara del extremo pequeño de la arandela del eje está más alta que el plano de referencia del anillo del asiento, antes de aplanar el anillo del eje, el punto A no estará más bajo que el plano de referencia, por lo que el bloque de soporte puede ser quitado y el cojinete se puede medir directamente en el banco de trabajo.

Las anteriores son algunas innovaciones e ideas de diseño del instrumento. La mayor innovación en el diseño del instrumento es convertir las dificultades de medición (el anillo exterior y el anillo interior pueden oscilar entre sí) que deben superarse en los dos métodos de medición originales en ideas de diseño. Y a través del instrumento de medición para lograr una medición rápida y precisa.

6. Análisis de errores de medición

(1) Análisis del principio de medición: la rigidez y la precisión de fabricación del instrumento están garantizadas (la precisión de fabricación del instrumento se refiere principalmente a dos aspectos: la precisión de coincidencia del diámetro exterior del eje roscado trapezoidal y la apertura en voladizo, y el paralelismo de la placa de presión con respecto a la mesa de trabajo). Además, con las características de protección del sistema contra sobrecarga y el centrado automático del rodamiento probado, se puede garantizar la precisión de medición del instrumento y la medición y el posicionamiento son rápidos.

(2) Verificación del uso real: después de que se fabrica el instrumento, verificamos el error de medición en los siguientes dos aspectos:

Primero, repita la verificación de la medición con diferentes bloques de altura estándar. La Tabla 1 muestra los datos de verificación.

En segundo lugar, utilice el método de medición de mandril y el instrumento de medición para medir la altura de montaje del mismo conjunto de rodamientos GAC110S/K varias veces para verificar la repetibilidad de los resultados de la medición. Los datos de medición se muestran en la Tabla 2.

A partir de los datos de la Tabla 1, se puede ver que la precisión de la medición y la repetibilidad de los resultados de la medición están dentro de 0,01 mm; a partir de los datos de la Tabla 2, se puede ver que la repetibilidad del método del mandril es peor que la repetibilidad del instrumento de medición, lo cual es inconsistente con el método del eje central. Los defectos de medición del método axial están estrechamente relacionados. En conclusión, el dispositivo puede cumplir completamente con los requisitos de medición del producto (el valor de tolerancia de la altura del ensamblaje es superior a 0,1 mm).

7. Comparación de la eficiencia de detección

After the practical application of on-site production, this measuring instrument can reduce the labor intensity of inspectors, and improve the detection efficiency by nearly 10 times compared with the mandrel method (taking GAC110S/K as an example, the mandrel method is 30-40 seconds per piece, this measurement instrument for 3 to 5 seconds/piece).

8. Conclusion

The measuring instrument solves the problems of poor detection accuracy and high labor intensity of inspectors when using the original detection method.

The detection efficiency of this measuring instrument is nearly 10 times higher than that of the original detection method, and it can detect bearings of the same series of different specifications to meet the requirements of mass production.

Therefore, the design of the measuring instrument is a success.