Shock absorber

Overview

The JZ/H‑type all‑mechanical shock absorber uses a disc spring as its elastic element to absorb the jerking and vibrations of drilling tools. Its performance is unaffected by the operating environment, overcoming the reliance of conventional hydraulic shock absorbers on sealing integrity. It offers advantages such as a simple structure, reliable operation, convenient handling and maintenance, excellent shock‑absorption performance, and a long service life.

Basic Structure

The shock absorber’s core‑shaft assembly primarily comprises the core shaft, anti‑drop connector, impact tube, spacer sleeve, and float; the outer‑cylinder assembly mainly consists of the splined sleeve, intermediate cylinder sleeve, lower cylinder sleeve, and lower connector.

• The shock absorber transmits torque via a splined sleeve.
• Elastic element in the damping chamber: disc spring.

Working principle

This shock absorber is installed between the drill bit and the drill collar. Drilling weight is transmitted via the mandrel and the drop‑prevention joint to compress the disc springs, which in turn apply force to the cylinder liner and then to the drill bit. Conversely, when the drill bit experiences stick‑slip or vibration, these forces compress the disc springs, absorbing energy and achieving shock absorption. During operations such as tripping out or moving the drill string—when the drill string needs to be lifted—the lifting load passes through the mandrel and the ram‑pipe joint to compress the disc springs, which then transmit the force to the cylinder liner and raise the lower portion of the drill string. Thus, this shock absorber exhibits a degree of elasticity under tension, helping to reduce damage to the drill string caused by lifting.
This shock absorber employs a steel disc spring as its elastic element, offering a long service life. Its all‑mechanical design eliminates reliance on seals for performance, ensuring more reliable operation. Moreover, its stiffness can be adjusted to meet user requirements, enabling the tool to adapt to varying drilling loads and achieve optimal vibration‑damping performance.

Preparatory operations before entering the well

1. Inspect the upper and lower drill pipe connections to ensure they are in good condition and free from damage incurred during transportation; connections must be securely tightened.
2. Before entering the well, inspect the chrome-plated surface of the tool mandrel for any damage.
3. Inspect the certificate of conformity and the markings on the tool’s outer packaging to verify the tool number, manufacturing date, inspection status, and other relevant information.
4. The drill string configuration shall position the shock absorber close to the drill bit to ensure effective vibration damping and protect the drill bit.
5. After the shock absorber is installed on the drill string, remove the clamp and store it properly for use during tripping operations.

Technical Specifications

Precautions

1. Before use, the lifting system and equipment must be inspected to ensure they are in good working condition.
2. When tightening with large pliers, it is strictly prohibited to allow the jaws to grip the oil plug or the threaded connection, to prevent damage to the oil plug or the threads.
3. The shock absorber must not be used when there is a dropped object at the bottom of the well or during fishing operations.
4. For optimal performance, the tool should be installed at the over‑bit position.
5. During tool operation, do not exceed the tool’s maximum working torque, maximum tensile strength, maximum allowable drilling pressure, or other specified limits.
6. When a tool has reached its rated service life, it must be sent for inspection and maintenance, regardless of whether it is damaged.
7. After use, rinse the shock absorber’s exterior surface and the water ports to remove any mud; flush the oil‑seal area; clean the chrome‑plated surface of the core shaft; wipe dry, apply calcium‑based grease, install the retaining clamp, and fit protective threads on both end fittings.