Embossing Roller Hob Machining for Rounded Protuberances
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Solution Overview
Problem
Current methods for producing embossing rollers with protuberances of truncated cone or pyramid shapes are costly and time-consuming due to the need for chemical treatment, laser processing, or chip-removal machining followed by grinding, which results in uniform protuberance heights and sharp edges that cause mechanical stress and uneven chrome plating, limiting the mechanical characteristics and feel of embossed paper products.
Innovation Solution
A method using chip-removal machining with a hob to generate protuberances of truncated pyramids without subsequent grinding, allowing for varied heights and radiused top surfaces to reduce mechanical stress and improve feel, and eliminating sharp edges and acute vertices, thereby enhancing the embossing process and reducing wear on pressure rollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chip-removal machining followed by grinding is used to produce embossing rollers, then manufacturing precision of protuberance height is improved, but production time and cost increase
Solution Approach 1:
The invention extracts and eliminates the grinding operation from the traditional two-step manufacturing process (chip-removal machining followed by grinding). By using a specially designed hob with optimized geometry and parameters, the protuberances are machined directly to the required height precision in a single chip-removal operation, removing the need for the subsequent grinding step that consumed excessive time and resources.
Solution Approach 2:
The invention changes critical machining parameters including hob geometry (modified tooth profile and helix angle), cutting speed, feed rate, and depth of cut to achieve the desired protuberance height precision directly in the chip-removal machining step. These parameter optimizations enable the single-step process to meet manufacturing precision requirements that traditionally required the additional grinding operation.
2Manufacturing precision
If traditional chip-removal machining with grinding is used, then protuberance height precision is improved, but sharp edges and acute vertices are created causing mechanical stress
Solution Approach 1:
The invention applies spheroidality by designing the hob to generate protuberances with rounded top surfaces and curved transitions instead of sharp edges and acute vertices. The modified hob geometry creates protuberances with radiused edges that eliminate stress concentration points, thereby reducing mechanical stress on paper fibers during the embossing process while maintaining the required height precision.
Solution Approach 2:
The invention applies local quality by creating different surface characteristics on different parts of the protuberances. The tops of the protuberances have a rounded, stress-distributing geometry, while the sides maintain the precision machining characteristics. This localized differentiation allows the protuberances to meet height precision requirements while eliminating harmful sharp edges at critical stress points.
3Manufacturing precision
If uniform grinding is applied to all protuberances, then height consistency is improved, but chrome plating becomes uneven
Solution Approach 1:
The invention extracts and eliminates the uniform grinding step that caused uneven chrome plating. By using optimized chip-removal machining parameters and hob geometry, the protuberances achieve the required height consistency directly during the machining process, without the need for subsequent grinding that created surface variations affecting plating uniformity.
Solution Approach 2:
The invention replaces the mechanical grinding system with an optimized chip-removal machining system that uses controlled material removal through carefully selected cutting parameters. This substitution allows for more precise control over protuberance geometry and surface quality, resulting in more uniform chrome plating while maintaining height consistency.
4Object-affected harmful factors
If chemical treatment or laser processing is used to create rounded protuberance tops, then mechanical stress is reduced, but production cost and time increase
Solution Approach 1:
The invention merges the geometry creation and surface rounding operations into a single chip-removal machining step using a specially designed hob. Instead of performing separate operations (chip-removal machining followed by chemical treatment or laser processing), the optimized hob simultaneously creates the protuberance shape and rounds the tops, eliminating additional production steps and reducing both time and cost.
Solution Approach 2:
The invention replaces chemical treatment and laser processing operations with an optimized mechanical chip-removal machining process. The specially designed hob with modified geometry and optimized cutting parameters directly creates the rounded protuberance tops during the initial machining operation, substituting expensive and time-consuming chemical or thermal processes with an efficient mechanical solution.
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 approach reduces production costs and time, improves the mechanical characteristics and feel of embossed paper, minimizes localized stresses on paper fibers, and extends the life of pressure rollers by eliminating sharp edges and uneven chrome plating, resulting in more efficient and effective embossing with better product quality.
Implementation Method 1
A method using chip-removal machining with a hob to generate protuberances of truncated pyramids without subsequent grinding
Data Source
Figure 1~2
Figure 3~4
Figure 5~6B
AI summary
Described herein is a method for obtaining an incision in an embossing roller using a hob, with a low-cost technique that enables protuberances P that are rounded on top to be obtained, which improve the quality of the embossed material and reduce the wear of the mechanical components of the embossing units. The shape of the protuberances (P) is obtained by machining the cylindrical surface of the roller (1) that is placed between the tailstocks of the lathe using a hob that has teeth, the profile of which in cross-sectional view is complementary to that of the cross section of the protuberances illustrated in Figure 6. Figure 6 shows schematically in cross-sectional view a portion of the surface of the roller with protuberances in the machining step and a portion of the hob (10) with the teeth (D) that are generating the grooves that define the side faces of the protuberances . As may be noted in Figure 6A, the grooves between the teeth of the hob have a profile that is curvilinear in a cross-sectinoal view. With a double pass othis taccording two different inclinations of the surface of the roller the protuberances of Figure 5 and 6 are generated.