Joytech Hammer

Description

The JOYTECH JT Series hammers are valve less, pneumatically operated tools designed to use with 3" to 40" diameter bits in rock formations under a wide range of operating conditions.

The JOYTECH hammers incorporate thick hardened wear sleeves. The simple design of the JOYTECH hammers provides performance, dependability and ease in servicing.

The JOYTECH hammers are designed for universal applications using air pressure 100psi to 350psi (7bar to 24bar), with some exceptions of special models.

Operation

• Check if the chuck and the back head are firmly tightened.
• Lubricate the hammer with rock drill oil. DTH Hammers need 0.2 litre/hour of oil per 3m³/min of air consumed
• Connect to the hammer to the drill string.
• Open the hammer lubricator valve to continually inject oil into the air stream whilst the hammer is operating
• Start to drill after checking safety
• Rotation Speeds
  As a general guide, the harder the rock or the larger bit diameter, the slower the rotation speed required. It may be necessary however to increase the rotation speed where the rock is badly fissured in order to prevent stalling.

Thrust(Pull down) / Holdback / Torque

• Thrust should be kept as low as possible at all time avoiding excessive vibration in the drill string.
• Holdback should be increased more and more as additional pipes are added, as drilling progresses.
• Although the base of the hammer should maintain contact with the bit, there should be neither excess thrust nor vibration due to reaction between the hammer and the bit Insufficient thrust will cause the hammer to bounce resulting in a low blow energy to the rock causing vibration and also possible damage.
• DTH bits unlike rotary tritons require very little rotation torque

Drilling depth capability

• The depth capability with DTH hammers is governed by two main factors, sufficient air volume to keep the hole clean and the drill rig’s lifting power.
• On deep hole applications, such as water well drilling, it is essential that the drill rig has sufficient lifting power with a reserve of power(safety factor) for contingencies such as the drill rig’s hydraulic system inefficiency, the weight of the rotary head/hammer/bit, friction in the hole, potential hole collapse etc. In reality, only around half of gross lifting power can be used.