Grinding method on cylindrical grinding machine

1. Grinding the Outer Circle

The outer surface of a workpiece is typically ground using a standard cylindrical grinder or a universal cylindrical grinder. There are generally three types of cylindrical grinding methods: vertical, horizontal, and deep grinding.

Fig. 1 Grinding of the Outer Circle

(1) Longitudinal Grinding Method As shown in Fig. 1a, when using the vertical grinding method, the grinding wheel rotates at high speed as the main cutting motion, while the workpiece performs a circumferential feed movement and a longitudinal reciprocating motion along the table to achieve the edge movement. The workpiece also moves axially with a feed rate fa. At the end of each single stroke or after every reciprocating movement, the grinding wheel makes a periodic lateral feed fr in the radial direction of the workpiece, gradually removing the entire radial grinding allowance. After reaching the desired size, a light finishing pass is performed without lateral feed until the sparks disappear. This method offers good accuracy and surface quality due to its small radial feed rate, low grinding force, and efficient heat dissipation. However, it has lower grinding efficiency. The longitudinal grinding method is ideal for large workpieces and is commonly used in single-piece or small-batch production.

Table 1 Characteristics of Longitudinal Grinding

(2) Cross-grinding Method As shown in Fig. 1b, the cross-grinding method involves a wider grinding wheel that covers the full width of the workpiece. In this method, the workpiece does not need to move longitudinally, and the grinding wheel moves transversely at a slow speed, either continuously or intermittently, to achieve radial feed fr. This method fully utilizes the cutting capacity of the grinding wheel, offering high efficiency and suitability for forming operations. However, the large contact area between the wheel and the workpiece increases grinding force, which can cause deformation and burning. Additionally, the wheel's shape errors directly affect the workpiece geometry, resulting in lower accuracy and higher surface roughness. Therefore, a rigid machine with sufficient power and coolant is required. This method is suitable for short shafts or journal grinding.

Table 2 Characteristics of the Horizontal Grinding Method

(3) Deep Grinding Method As shown in Fig. 1c, the deep grinding method is more advanced and highly productive, with a typical grinding allowance of 0.1~0.35 mm. It allows for one-pass machining of the entire material. The feed rate is small, usually around 1~2 mm/r, which is about 15% of the longitudinal grinding method. Processing time is approximately 30~75% of that of the longitudinal method.

Table 3 Characteristics of Deep Grinding Method

(4) Hybrid Grinding Method: This method combines the advantages of both longitudinal and cross grinding, offering improved efficiency and precision. It is particularly useful for complex shapes where a single technique may not be sufficient.

Table 4 Characteristics of Hybrid Grinding

2. Grinding the End Face On a universal cylindrical grinder, the end face of the grinding wheel can be used to grind the shoulder and flat surfaces of the workpiece. Before starting the grinding process, the end face of the wheel should be brought slowly close to the workpiece surface. During grinding, the axial feed of the workpiece should be kept minimal, as the rigidity of the grinding wheelâ€™s end face is poor and cannot withstand large axial forces. The best approach is to use the conical surface of the grinding wheel to grind the end face, which requires adjusting the worktable to a larger angle.

3. Grinding the Inner Circle The inner circle of a workpiece can be ground using a cylindrical grinder. When grinding the inner surface, the workpiece is typically positioned using the outer diameter or end face and clamped in a chuck (see Figure 2). To grind an internal conical surface, the grinding tool is simply angled appropriately.

Figure 2 Grinding of the Inner Circle

Unlike cylindrical grinding, inner circle grinding is limited by the workpieceâ€™s hole diameter, which is usually smaller. This results in faster wear of the grinding wheel, requiring frequent dressing and replacement. The grinding wheel used for internal grinding is softer than those used for external grinding because of the larger contact area. Additionally, the smaller diameter of the grinding wheel shaft leads to reduced rigidity and increased overhang, limiting the depth of cut and reducing productivity.

Chest Muscle Training

The fitness equipment for chest exercises has diverse characteristics and can meet different training needs and goals. ‌

1. Barbell bench press is one of the most common training exercises for chest muscles, mainly training the pectoralis major, shoulders, and triceps. When using a barbell push, it is important to maintain a straight back and stable shoulder blades, avoid excessive use of shoulder and arm strength, and adjust the weight and frequency of the barbell to suit your level of ability. ‌

2. Dumbbell bench press is another common exercise for training chest muscles, which places more emphasis on the stability and balance of the chest muscles compared to barbell bench press. When using dumbbell push, it is necessary to maintain the stability of the arms and try to keep the movements of both arms consistent. A smaller weight can be used for dumbbell push to improve stability and grip. ‌

3. A chest stretcher is a device specifically designed to train chest muscles, which can be adjusted to different body shapes and training needs by adjusting the position of the seat and handle. The advantage of chest thrusters is that they can more effectively isolate and stimulate the pectoralis major muscle while reducing the impact on other muscle groups. ‌

4. A fitness ball is a multifunctional equipment that can be used for various training exercises, including chest training. By performing exercises such as bench presses and push ups on the fitness ball, the challenge and stability requirements for the chest muscles can be increased. ‌

5. The pull-up device is used to exercise upper body muscles, including chest muscles. By performing pull ups, the development of chest muscles can be effectively stimulated. When using the pull-up device, it is important to maintain correct posture and movements, avoid shaking and excessive use of arm strength.

In addition, other equipment such as butterfly machines, fitness ropes, barbells, and flying birds can also be used for chest exercises. No matter which equipment is chosen, the key is to maintain correct movements and postures, grasp appropriate weight and frequency to avoid injury and achieve the best training results

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Tool Selection Decision Model and Application for Green Manufacturing

Grinding method on cylindrical grinding machine