|
|
 |
| Drum Chippers |
|
The SKD (Straight Knife Drum) Chipper uses straight-edged knives mounted across the face of a cylindrical drum, fed from an inclined chute, to produce quality chips. The knife and discharge screen arrangements can be varied and fine-tuned to match a wide variety of furnishes (wood sizes and types).
Download SKD Drum Chipper Brochure ( PDF 456 KB)
The anvil is mounted on a robust shear pin-protected pivoting carrier. This helps protect against damage from large pieces of metal or other unintended foreign objects. The overall chipper construction is exceptionally sturdy and maintainable.
Application
An SKD, a gravity-fed chipper, can be set to handle any of a wide variety of furnishes. These include logs, boards, trim ends, edgings and short log ends (“lily pads”).
The versatility of SKD chippers has allowed them to be successfully applied to a number of specialized unconventional situations such as processing stringy bark, veneer waste, re-processing oversize chips and mobile applications.
Standard Features
- Large infeed spout opening.
- Close control of knife-anvil clearance - adjustment screws at the chipper shaft pillow blocks allow the drum to be positioned to the desired knife clearance. Generously sized access covers at both sides of the chipper base allow close inspection of the anvil sections and knife clearance.
- Carbide-edged anvil - each 16 inch long anvil section is equipped with two edges and is reversible. The anvil edges are made from wear resistant tungsten carbide.
The anvil sections can be reversed and interchanged to obtain maximum life. They are mounted in a precision-machined pocket in the pivoting anvil carrier.
- Shear pin-protected pivoting anvil carrier - large opening for drop-out of foreign objects if the carrier is released.
- Ample room for knife service - large hinged top cover provides easy access to knives. Generous clearance to the face and both ends of the chipper drum.
- Rugged construction drum, with integral thick support block at knife clamping area. Field-replaceable threaded bushings allow complete renewal of knife clamp bolt anchoring threads when needed.
- Grate-type screen under the drum is standard. Typical design of this screen virtually eliminates oversize chips.
- Screen clearance is fully adjustable from outside the chipper base, using conveniently located screw-positioned supports.
- Generous openings at rear and top of chipper base for screen maintenance and replacement.
- Bottom discharge is standard - large bottom opening gives unimpeded discharge.
- Oversized shaft, mounted to drum with field-proven heavy duty locking elements, allows easy field change-out of shaft or drum if required.
- Rugged SKF ductile iron split housing pillow blocks.
Gravity Feed Configuration
The spout slopes downward into the chipper. The slope angle is chosen to ensure smooth feeding. A thick flange surrounds the spout entrance. The flange includes holes for attachment of the customer’s infeed chute.
It is important that the customer-provided infeed chute be designed for smooth flow of material into the chipper. This means the internal width of the infeed chute should be slightly narrower than the chipper spout. The entrance into the infeed chute should be narrower still, so that material sliding down toward the chipper is always moving into a slightly larger opening. The chute should be free of any pockets, projecting edges or lips that might catch material.
For specialized applications such as bark processing, the chipper can be mounted on an inclined base to provide an even steeper drop angle.
Chipper Hand
Handing is determined according to which side the chipper drive is on. This is as viewed when looking toward the chipper from the infeed end of the base. A Left Hand chipper will have the chipper drive at the left side of the base. Right hand is opposite.
Number of Knife Pockets (number of cuts per revolution of chipper drum)
Drums can be supplied for 2, 4 or 6 knife pockets.
Drums can be equipped with optional knife pocket blanking plates at opposite knife pockets. The blanking plates fit in place of the knives and clamps at those pockets. This may be done when a chipper is selected and installed with a higher future production rate in mind, but is to be initially used at a lower rate and with a smaller capacity chipper drive.
Options
Disposable Knives
A Key Knife disposable knife system can be provided. Installation is simple. Only the knife and counter knife are replaced. The same knife clamp is used as for conventional babbitted knives.
Babbitt Fixture
a babbitting fixture is required for all knife types except disposable knives. It is used to pour Babbitt shims behind newly ground knives. The shims put the knives at a controlled depth, ready for re-use.
Special Counterknives
Ridged-front counterknives are available for use with conventional knives. The sharp ridges bend and help break up over-width chips (“ribbons”). However they also increase the amount of pins and dust.
Momentum Discharge (no internal screen)
The chipper can be supplied for momentum discharge. The standard screen below the drum is replaced with close-fitting abrasion-resisting shroud plate. This plate in turn leads to a rectangular discharge duct at the rear of the chipper.
Because of the absence of a screen, and depending on the furnish, a higher quantity of oversize chips and sticks can be produced.
Chips leave the chipper, moving at high speed (up to 6000 ft/min = 30 meters/sec).
Momentum discharge is used in some agricultural applications where the furnish is woody and dry, close control of particle size is not important, and the conveying distance is short (15 feet or less). Because of the less control of particle size distribution and the conveying problems that can develop with fluffy or rotted wood and sticky wet materials, momentum discharge is rarely recommended.
Bottom Discharge (no screen)
The chipper can be supplied for bottom discharge, but without a screen. This may be suitable for some unusual situations where chip bruising and breakup must be kept to the absolute minimum. Without a screen, and depending on the furnish, a substantial quantity of oversize chips and sticks is likely to be produced.
A screen and its supports can be field-installed later, without modification to the basic chipper.
Bottom Discharge - With Grate Screen
This is the standard discharge arrangement. Various screen configurations are available according to furnish and desired chip size. Standard screens provide outstanding control of oversize chips. Variations are available to suit particular situations.
Four externally mounted support blocks with screw adjustments allow the screen to be precisely positioned to the knives for best control of chip size.
Drum Stopping Brake
A caliper-type disc brake is used. The brake disc mounts direct to the chipper shaft, at the opposite side of the chipper from the chipper drive. The shaft is made longer to accept the brake.
Provided that the chipper shaft was originally specified for use with a brake, the stopping brake can be added in the field. If field installation is anticipated, “brake-capable” shaft should be specified when the chipper is ordered.
If a guard is required at the stopping brake, this should be specified on the order.
Chipper Motor and Drive Option
Complete drive packages are available. The simplest arrangement is to mount the sheaves directly on the motor and chipper shafts.
A motor slide base is provided, to allow moving the motor for installation and tensioning of the drive belts.
The safety guard completely encloses the V-belt drive. It is floor-mounted and shipped loose for installation by the customer.
Acrobat Reader is required to view PDFs. Download for free if needed.
|
|
|
