Index judgment in furniture production: processing benchmark, accuracy, and surface roughness!
In the furniture production process, factories often need a series of indicators to ensure the product quality of furniture, evaluate the quality of products, and reduce problems in the production process.
These indicators include machining benchmark, machining accuracy, surface roughness, and machining allowance. In this issue, we will discuss three indicators of furniture production: processing benchmark and processing
Accuracy and surface roughness.
Processing reference
When processing workpieces on a machine tool, in order to meet the corresponding technical requirements of the process, the workpiece must first be positioned and clamped before processing.
Positioning and clamping
Positioning: When cutting, the workpiece must be placed on the equipment or fixture first, so that it has a correct relative position with the tool
Positioning is called positioning.
Clamping: After clamping the workpiece, it cannot withstand the cutting force during processing. In order to maintain its correct position during the processing, it is necessary to adjust it according to the requirements
Fixed in the specified direction, this type of fixation is called clamping.
At the same time, determining the machining benchmark before machining is an important preparatory work for mechanical machining, which has a significant impact on machining accuracy and production efficiency. The so-called machining benchmark is used for
A point, line, or surface used to determine the position of a cutting tool and the processed part, or to determine the relative position between parts in a product.
Benchmarks can have multiple functions, which can be classified into two categories based on their different functions: design benchmark and process benchmark. Process benchmark can also be used for different purposes
It is divided into measurement reference, positioning reference, and assembly reference.
Design Basis and Process Basis
Design Basis: The design refers to the points, lines, and surfaces used on the drawing during product design to determine the positions between components and holes in the production process
Benchmark.
Process benchmark: A point used in measurement, processing, or assembly to determine the relative position with other surfaces on the component or with other components in the product
Line and surface are referred to as process benchmarks.
To ensure product quality, we need to measure whether the dimensions and shapes of the processed parts meet the requirements.
It can be roughly classified into two evaluation methods: the standard for evaluating machining accuracy is based on the degree of conformity between the product and the drawing; Evaluated based on product and actual error values
The standard is machining error.
Processing accuracy and error
Processing accuracy: refers to the actual and theoretical values (as specified on the drawing) of geometric parameters such as size, shape, and position obtained from the workpiece after processing, which match the actual values
The degree of.
Processing error: refers to the actual size, shape, and position of a workpiece that does not match the theoretical size, shape, and position specified on the drawing after processing
The deviation of life.
The occurrence of processing errors is accidental and inevitable. Based on these two situations, processing errors can be divided into systematic errors and accidental errors.
Systematic and accidental errors
Systematic error: When processing a batch of components in sequence, the machining error remains unchanged or varies according to a certain pattern, which is called systematic error.
Accidental error: When processing a batch of components, if the error value is not fixed or does not conform to a certain negative pattern, this error is called accidental error
Or random error.
In order to improve production efficiency and reduce production costs, when determining processing accuracy, we also need to achieve a certain degree of interchangeability between products or parts. research
Interchangeability is of great significance for enterprise production.
Surface roughness
Processing accuracy is an important indicator for measuring the machining size and shape of components, while surface roughness is an important indicator for evaluating the surface machining quality of components.
Surface roughness: After cutting or pressure processing, wood or artificial boards will leave various machining marks or bumps on the processing surface
The unevenness observed is called the surface roughness of wood processing.
Surface roughness can be divided into two forms based on the appearance size of defects, namely macroscopic unevenness and microscopic unevenness.
Macro unevenness and micro unevenness
Macro unevenness: A single machining defect with a relatively large overall size.
Micro unevenness: A single machining defect with relatively small overall dimensions.
The surface roughness referred to in wood processing production is usually micro unevenness. Common surface defects after wood processing are usually divided into the following six types:
Elastic recovery unevenness: During cutting, the tool compresses the surface of the wood, and after releasing the pressure, the unevenness of the wood is formed due to the elastic recovery.
Cutting tool marks and ripples: Usually, the geometric shape of the cutting tool and the marks left during cutting motion are called cutting tool marks; The displacement caused by the stiffness of the process system is called ripple,
Collectively referred to as ripple marks.
Wood wool: One end of a single fiber is connected to the surface of the wood while the other end is erect or tightly attached to the surface of the wood.
Burr: Bundles or pieces of wood fibers that have not yet completely separated from the surface of the wood.
Destructive unevenness: The result of bundles of wood fibers peeling or tearing off the surface of wood during processing.
Structural unevenness: unevenness caused by the cutting of wood cell cavities, or small gaps formed by the arrangement of particles on the surface of particle boards, or due to the surface of wood
Surface unevenness caused by dry shrinkage and swelling of the surface.
