Road milling machine
Road milling machine ( cold milling machine) is a road machine designed for loosening and grinding soil (including asphalt concrete pavements). They are divided into self-propelled, mounted and trailed. Used for milling (removing) the top layer of road surfaces and, in some cases, the subsequent collection of the removed material for reuse. Often used in road repairs.
The first road milling machines were created by Galion Iron Works and resembled a grader in their shape and size. Instead of a knife, a milling drum 76 cm wide was installed on them. The drum was driven by a large hydraulic pump.
Modern self-propelled machines are much larger (up to 2-2.2 m wide) and often use four drive tracks, between which a drum is located. The milling drum is supplemented with throwing blades, and the machine is equipped with a system for collecting the removed material and a conveyor for loading it into vehicles. The largest road milling machines have a capacity of up to 13 thousand m³ per day. The cutting depth can be up to 35 cm.
Road milling requires special training. Some modern machines require the collaboration of two operators, one located on the machine itself and directly controlling, and the second located on the ground next to the machine and controls the depth of milling and the presence of obstacles (for example, manholes and storm drain grates).
Milling drum
The main tool of the road milling machine is the milling drum. The drum contains on its surface scoring tool holders (at the edges), a plurality (several hundred) of tool holders on the main surface and a number of throwing blades to collect the cut material. A cutter with a carbide tip is installed in each tool holder using a holder.
They are divided depending on the number, size and location of the cutters into types: Standard, Profiling, Micro-milling, Special, Stabilizing.
Drums allow quick replacement of worn cutters.
Main manufacturers
According to the article «The quality of work gives a cutter»
- XCMG
- Bitelli
- Caterpillar
- CMJ
- roadtec
- Weber
- Wirtgen
- DYNAPAC
- BOMAG
- TEREX
Mounted hydraulic road milling machines
In connection with the widespread use of road surface profiling technology, another type of road milling machine has recently been rapidly gaining popularity — hinged hydraulic
road cutters. A feature of these cutters is the fact that these are no longer self-propelled machines, but hydraulic attachments, which are used as the working body of the base machine.
Mounted hydraulic cutters can be operated with such types of equipment as:
- mini loaders
- backhoe loaders
- front loaders
- excavators
The standard design of hydraulic mounted milling cutters consists of a milling drum driven by a hydraulic motor and a mounting frame designed to attach the road milling machine to the base machine carrier. Optionally, these types of cutters can be equipped with drums and cutters for profiling various types of surfaces, a set for surface moistening, consisting of a tank and an electric pump, hydraulic side shift options that allow you to move the road milling machine in a horizontal plane using a hydraulic cylinder without leaving the cab (on cutters of some manufacturers, this function is enabled by default). The profiling depth and the inclination of the milling drum to the right or left can also be adjusted. The landing plate can also be replaced based on the media on which the cutter is planned to be used.[5]
Depending on the type of base machine, mounted hydraulic road milling machines require a hydraulic oil flow of 30 to 120 l/min for successful operation, while the profiling depth of such mills is from 130 to 170 mm, and the drum width can be from 250 to 1000 mm .
Mounted hydraulic road milling machines are widely used in patching where the use of self-propelled road milling machines is economically unprofitable, or impossible due to the dimensions of self-propelled equipment.