Pulp and Paper Machinery Installation and Maintenance

Author: Editor-in-Chief: Bian Gui
Publisher:
Publish Date: 2004-04-03
Features:
Section: Chapter Measurement Installation Tools and Lifting and Handling Machinery
Section: Measurement Installation Tools
Installation and repair work require various measurement tools. Here, a brief introduction is provided for some commonly used tools.
1. Feeler Gauge
Feeler gauge is also known as thickness gauge or gap gauge. It consists of a set of long, fixed thin metal strips. The thickness of each strip is marked on its surface. Each set typically includes 9 to 21 strips, with the minimum thickness being 0.02mm and the maximum thickness being 1mm. The length of feeler gauges is available in various sizes, such as 50mm, 100mm, and 200mm, as shown in Figure 1-1.
Feeler gauges are primarily used to measure the gap between two adjacent surfaces, such as bearing clearance, gear clearance, and the gap between impellers and casings. They can be used for single strip measurement or by selecting multiple strips to form a combination measurement.
Precautions for use:
- Clean off oil stains before use.
- Insert the gauge into the gap evenly and gently to avoid excessive looseness or tightness, which may lead to inaccurate measurements or wear.
- After measurement, clean the gauge with a clean oil cloth and store it in a bag or case.
2. Vernier Caliper
The structure of a vernier caliper is shown in Figure 1-2. The caliper includes a main scale and a vernier scale, with each division on the main scale measuring 1mm. The main scale also has two fixed measuring feet (2 and 3), while the movable frame (6) has two additional movable measuring feet (1 and 4), which can slide along the main scale (8). The locking screw (5) on the frame can secure it in the desired position.
Measuring feet (1 and 2) are used to measure external dimensions of parts, while measuring feet (3 and 4) are used to measure internal dimensions. One end of the frame is connected to a depth measuring rod (9). The frame also has a vernier (7). If the vernier has a total length of 9mm and is divided into 10 divisions, each division measures 0.9mm. Therefore, the difference between each small division on the main scale and each small division on the vernier is 0.1mm, making the precision of this vernier caliper 0.1mm.
For higher precision, the vernier can be divided into 20 or 50 divisions with total lengths of 19mm or 49mm, respectively, achieving precision levels of 0.05mm or 0.02mm. Based on this principle, vernier calipers can also be designed for different purposes, such as height and depth measurements.
3. Micrometer
A micrometer, also known as a screw micrometer or vernier micrometer, can achieve a measurement precision of 0.01mm. Depending on the application, micrometers are categorized into various types, such as external micrometers, internal micrometers, and depth micrometers, each available in different specifications.