July 20, 2023
The mold frame is the key component of the bottle blowing machine and one of the core components of the beverage packaging machinery. The frame is a key part used to support and guide the moving and fixed die moving parts of the bottle blowing machine die frame, and its machining accuracy directly affects the rotating speed of the bottle blowing machine and the opening and closing performance of the die frame. There are many reasons affecting the machining accuracy of the frame, such as: casting material, frame structure, positioning reference precision, pressing deformation, etc. The precision and compression deformation of the positioning reference will directly affect the coaxiality of the mounting hole (center shaft hole) of the moving and fixed die and the opening and closing performance of the moving and fixed die. As the frame belongs to thin and long parts with thin wall and cantilever box, it deforms greatly during processing, and the dimensional accuracy is difficult to be guaranteed. In the past processing, the key dimensions, such as coaxiality of central shaft hole and distance between swing arm holes, cannot be guaranteed, and the dimension is out of tolerance seriously, which cannot meet the performance requirements of the product. This process research and development solves this problem well and ensures the product quality.
1、 Part process analysis
The material of this part is ZG45, which is casted by the disappear die. From the drawing analysis, the total length is 787mm and the wall thickness is 14mm. The part belongs to thin-wall cantilever casting with poor rigidity and variability. It mainly consists of two groups of holes and three groups of planes. The coaxiality of the fixed circular hole of the central shaft is required to be 0.03mm within a distance of 400mm. The tolerance of the distance between the central shaft hole and the swing arm hole is required to be (128.36 ± 0.02) mm, (81.28 ± 0.02) mm. The perpendicularity of Φ26mm to Datum A is 0.04mm, the symmetry of the plane 70 mm to the center of the part is 0.02mm, and the surface roughness is 3.2ηm. It is high requirements.
2、 Brief Introduction to Frame Machining Process
Parts are inspected after being processed according to the process route, and the series of center shaft holes are: Φ26, Φ40, Φ42mm,coaxiality 0.15~0.25 mm;
Shaft hole Φ26mm and swing arm hole Φ47mm In the X direction, the hole pitch is 128.40~128.55mm; in the Y direction, the hole pitch is 81.36~81.51mm; The symmetry of the 70mm plane to the center of the part is 0.50-0.88mm, which reflects that the positioning of the product is unstable and the dimension is out of tolerance seriously.
The specific reasons are as follows:
3、Main measures for solving out-of-tolerance of workpieces
Thin and thin cantilever box parts are prone to two major problems in the processing and production process: deformation under the action of pressing force and distortion caused by the instability of the datum plane. These two factors are the main reasons for unqualified product quality. Therefore, the deformation caused by the installation and clamping of the parts can be effectively avoided by increasing the rough datum, ensuring the machining accuracy of the accurate datum, increasing the fixture positioning, correctly determining the clamping point position of the tooling and other measures, so as to ensure the quality and performance of the product.