Stepped Rotary Broach Geometry for Large and Deep Form Cutting
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Solution Overview
Problem
Conventional rotary broaches are limited in cutting large or deep forms, especially in hard metals, and require multiple tools and complex alignment, increasing costs and machining time.
Innovation Solution
A stepped rotary broach with progressively larger steps along its length, allowing for controlled wobbling motion to cut larger forms without the need for multiple broaches, by mounting the broach at a skew to the toolholder's rotational axis and using a series of cutting edges that progressively increase in size as it wobbles through the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional rotary broaches are used to cut large or deep forms, then the cutting capability is limited, but using multiple broaches increases device complexity and machining time
Solution Approach 1:
The broach is divided into multiple sections along its length, with each section having cutting edges of progressively larger sizes. This segmentation allows a single broach to perform the function of multiple broaches by engaging different sections at different depths of the workpiece, thereby increasing cutting capability while reducing the number of tools required
Solution Approach 2:
The invention transitions from using multiple separate broaches (one-dimensional solution) to a single broach with varying cutting edge sizes along its length (adding the dimension of axial position). This dimensional change allows the broach to cut forms of varying sizes and depths in a single operation, resolving the contradiction between cutting capability and device complexity
2Adaptability or versatility
If multiple broaches are used to achieve larger forms, then cutting versatility improves, but machining time and alignment complexity increase
Solution Approach 1:
Multiple cutting functions that would traditionally require separate broaches are merged into a single broach tool. The broach incorporates cutting edges of various sizes along its length, allowing it to perform multiple cutting operations in one pass, thereby reducing machining time while maintaining form size capability
Solution Approach 2:
The broach design enables continuous cutting action throughout its length, with each section contributing to the final form. As the broach is inserted into the workpiece, multiple sections engage simultaneously or sequentially, maintaining continuous material removal without the need to change tools, thus eliminating idle time associated with tool changes and alignment
3Length of stationary object
If conventional rotary broaches cut deep forms, then the cutting depth is limited, but increasing machine load occurs
Solution Approach 1:
Different sections of the broach have locally optimized cutting edges suited for specific depths and cutting requirements. The cutting edges are distributed along the length of the broach, allowing the machine to engage only the necessary sections for the given cutting depth, thereby reducing overall machine load while achieving greater cutting depth capability
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
Enables the cutting of larger forms and deeper profiles in a single operation, reducing machining time and machine load, and eliminating the need for multiple tools, while maintaining precise control and efficiency.
Implementation Method 1
The toolholder is designed with a built-in offset or eccentricity that causes the broach to wobble slightly as it rotates. The bearing or bushing is eccentrically mounted within the toolholder, such that it is not perfectly centered.
Implementation Method 2
The broach is placed at a slight angle to the centerline of the workpiece. This causes the broach to cut with a chiseling or scalloping effect when the broach is rotated around the centerline of the toolholder.
Data Source
AI summary
Stepped rotary broaches, and systems and methods employing such broaches, are disclosed herein. In one example embodiment, a stepped rotary broach includes a contact portion integrally formed with or coupled to a support portion. The contact portion includes a face and a periphery. The periphery includes an outer surface and a plurality of step formations, where each of the step formations extends between the face and a respective location along the periphery at which the respective step formation adjoins a respective portion of the outer surface. Each of the step formations includes a respective step including a respective surface region extending in a respective direction about a central axis of the stepped rotary broach. The respective surface regions of the respective steps are respectively positioned more closely to the central axis than are the respective portions of the respective outer surface that respectively adjoin the respective step formations.