Hammer Drill Composite Transmission Housing
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Solution Overview
Problem
Existing hammer drill designs face challenges in achieving balanced support for transmission mechanisms, as they typically require precise manufacturing of metal clam shells, which can be costly and inflexible, while plastic clam shells are more affordable but lack rigidity. The assumption that using a combination of metal and plastic clam shells would result in unbalanced support has been disproven.
Innovation Solution
A hammer drill design featuring a transmission housing composed of a metal clam shell for rigidity and a plastic clam shell for flexibility, with semi-circular seals molded into the housing portions to simplify assembly and provide consistent support, allowing for reduced manufacturing tolerances and improved ease of manufacture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal clam shells are used for the transmission housing, then rigidity and support are improved, but manufacturing cost and complexity increase
Solution Approach 1:
The transmission housing combines metal and plastic materials in a composite construction. The metal clam shell provides rigidity and structural support, while the plastic clam shell reduces manufacturing cost and allows for easier production. This composite approach resolves the contradiction by integrating the advantages of both materials.
Solution Approach 2:
Different parts of the transmission housing have different material properties tailored to their specific functions. The metal portions are used where rigidity and strength are critical for supporting transmission components, while plastic portions are used where cost reduction and manufacturing ease are priorities. This local differentiation resolves the contradiction between rigidity and manufacturing cost.
2Strength
If metal clam shells are used for the transmission housing, then rigidity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The combination of metal and plastic materials allows the design to leverage the dimensional stability of metal where precision is needed while using the flexibility of plastic to accommodate manufacturing tolerances. The plastic clam shell can flex to compensate for tolerance variations, reducing the overall precision requirements while maintaining rigidity through the metal components.
Solution Approach 2:
The plastic material's ability to flex and deform allows the housing to accommodate a wider range of dimensional tolerances during manufacturing. This parameter change in material behavior compensates for variations in manufacturing precision, allowing rigid metal components to be used without requiring extremely tight tolerances.
3Ease of manufacture
If plastic clam shells are used for the transmission housing, then manufacturing cost is reduced, but rigidity and support decrease
Solution Approach 1:
The transmission housing uses a composite structure where plastic and metal materials are combined. The plastic clam shell provides cost-effective manufacturing and flexibility, while the metal clam shell contributes rigidity and structural support. This composite approach resolves the contradiction by distributing the functional requirements across different materials.
Solution Approach 2:
The housing design applies different materials to different regions based on local requirements. Plastic is used in areas where cost reduction is prioritized and structural demands are lower, while metal is used in areas requiring high rigidity for component support. This local quality differentiation resolves the contradiction between manufacturing cost and rigidity.
4Ease of manufacture
If combination of metal and plastic clam shells is used, then manufacturing flexibility and cost are improved, but support balance was assumed to be compromised
Solution Approach 1:
The transmission housing employs a composite metal-plastic construction that combines the manufacturing advantages of both materials while achieving balanced support for transmission components. The design carefully distributes the structural loads across both materials, ensuring that the plastic portions provide adequate support where needed while the metal portions handle high-stress areas, thus resolving the contradiction between manufacturing flexibility and support balance.
Data Source
AI summary
A hammer drill comprising: a body; a motor mounted within the body; a transmission housing mounted within the body, a transmission mechanism mounted within the transmission housing which is capable of rotatably driving and/or repetitively striking a cutting tool held by the hammer drill in response to rotation of an output shaft of the motor; wherein the transmission housing comprises a pair of housing portions adapted to engage each other to support the component parts of the transmission mechanism within the transmission housing; wherein the first housing portion is made from metal and the second housing portion is made from a plastic material, each of the components of the transmission mechanism being supported jointly be the first and second housing portions.