Construction Machine Arm Top Segmentation for Mold Complexity
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Solution Overview
Problem
Existing methods for producing arms for construction machines by casting result in high stress concentration and difficulty in achieving high production accuracy due to complex and large molds required for integrally forming the arm top.
Innovation Solution
The arm top is divided into left and right pieces formed by casting, which are then welded together at specific surfaces to form the first and second connection portions, allowing for easier production with improved accuracy and reduced stress concentration by integrating the pieces over the entire circumference, rather than at stress-prone joints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the entire arm top is integrally formed by casting, then the arm top has high strength without weld stress concentration, but the mold becomes large and complicated making production difficult and accuracy hard to achieve
Solution Approach 1:
The arm top is divided into two separate cast pieces (left and right) that are individually formed by casting and then joined together by welding. This segmentation allows each piece to be produced using simpler, smaller molds while maintaining overall structural integrity through the welding connection between the pieces
Solution Approach 2:
The left and right cast pieces are merged together through welding at specifically designed welding portions. This combining approach achieves the strength of integral formation while avoiding the manufacturing difficulties of large complex molds, as the welding portions are designed to minimize stress concentration
2Strength
If the entire arm top is integrally formed by casting, then the arm top has high strength without weld stress concentration, but production accuracy becomes difficult to obtain
Solution Approach 1:
Dividing the arm top into separate left and right cast pieces allows each piece to be produced with higher precision using smaller, simpler molds. The segmentation enables better control over casting parameters and mold complexity for each individual piece, resulting in improved overall production accuracy
Solution Approach 2:
The left and right pieces are pre-formed by casting with predetermined welding portions designed in advance. These welding portions are specifically shaped and positioned to ensure accurate alignment and minimal stress concentration when the pieces are joined, thereby maintaining high production accuracy in the final assembled product
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 simplifies the mold design, enhances production accuracy, and reduces stress concentration, resulting in a stronger arm top with improved welding reliability and workability, while protecting welds from wear during use.
Implementation Method 1
The left and right arm top pieces are joined together by welding at the opposed surfaces of the first left boss and the first right boss, at the opposed surfaces of the second left boss and the second right boss, and at the opposed surfaces of the left projecting wall portion and the right projecting wall portion, thereby being integrated to form the arm top
Data Source
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AI summary
Provided is an arm for a construction machine, including an arm top formed by casting, being easily produced with high dimensional accuracy. The arm includes an arm body 14 and an arm top 25. The arm top 25 is formed of left and right arm top pieces P1, P2 individually formed by casting and joined together. The left and right arm top pieces P1, P2 include first left and right bosses 28a, 28b constituting a fist connection section 28, second left and right bosses 29a, 29b constituting a second connection portion 29, and left and right projecting wall portions 30a, 30b constituting a connection wall 30 connecting the first and second connection portions 28, 29 to each other, respectively. The left and right arm top pieces P1, P2 are joined together by welding at respective opposing surfaces of the first left and right bosses 28a, 28b, those of the second left and right bosses 29a, 29b and those of the left and right projecting wall portions 30a, 30b, thereby forming the arm top 25.