Glass Blank Horizontal Pressing Surface Roughness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The vertical direct press method for manufacturing glass blanks for magnetic disks results in high surface roughness due to mold release material attachment, leading to reduced yield and accuracy in shape processing, as well as potential breakage during cutting processes.
Innovation Solution
A horizontal direct press method is employed, where a falling molten glass lump is press-formed using a pair of dies with controlled temperature, preventing fusion to the dies and eliminating the need for mold release materials, thus achieving lower surface roughness and improved flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mold release material is attached to the lower die to prevent fusion, then the glass blank can be removed from the die, but particles of the mold release material are attached to the glass blank surface, increasing surface roughness
Solution Approach 1:
The patent removes the mold release material from the process entirely by changing to a horizontal direct press method where the glass blank is formed between two moving dies without attachment to a stationary lower die, eliminating the source of surface roughness
Solution Approach 2:
The patent changes the pressing method from vertical to horizontal direction, and controls the temperature of the dies to be lower than the glass transition temperature, which prevents fusion and eliminates the need for mold release materials
2Ease of manufacture
If the surface roughness of the glass blank is large, then the glass blank can be formed without strict die surface control, but the yield of scribing is reduced and circularity and concentricity are deteriorated
Solution Approach 1:
The patent controls the temperature of the dies to be lower than the glass transition temperature of the glass material, which prevents fusion and allows formation of glass blanks with surface roughness of 0.01 µm or less, ensuring high yield in subsequent scribing processes
3Device complexity
If the glass blank is formed by vertical direct press method, then the forming process is simple, but the surface roughness is large due to attached particles of mold release material
Solution Approach 1:
The patent inverts the conventional vertical pressing method by using horizontal pressing where the die moves horizontally to form the glass blank between two dies, eliminating the need for mold release material and achieving smooth surface finish
Solution Approach 2:
The patent changes the pressing direction from vertical to horizontal and controls the die temperature to be lower than the glass transition temperature, which prevents fusion and eliminates the need for mold release materials while maintaining process simplicity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of glass blanks with reduced surface roughness and improved flatness, enhancing the accuracy of shape processing and increasing yield without the need for subsequent grinding or polishing, while maintaining high circularity and concentricity.
Implementation Method 1
press forming is performed while the temperature of the pair of dies, over a period of time until a molten glass is separated from the die after coming into contact with the die, is set at a temperature lower than a glass transition point (Tg)
Data Source
AI summary
A method for manufacturing a glass substrate for magnetic disk is provided in which a glass is kept from being fused to a mold during press forming and shape processing to achieve a good circularity is efficiently performed. The method includes: a forming process of forming a disk-shaped glass blank by direct-pressing a molten glass by a pair of dies; and a shape processing process of performing at least one of inner hole formation and outer shape formation for forming a disk-shaped glass substrate by forming a cutting line on the principal face of the glass blank, followed by growing the cutting line to perform cutting. In the forming process, press forming is performed while the temperature of the pair of dies, over a period of time until a molten glass is separated from the die after coming into contact with the die, is set at a temperature lower than a glass transition point (Tg) and a mold release material is not attached to the surfaces of the pair of dies.