Wire Rod Block

Background


Around 1945, Morgårdshammar marked a new epoch in the rolling mill technology. Housingless units replaced the conventional heavy housing stands. Advantages such as optimum stiffness, low weight, and easy handling implied higher yields, better tolerances, and increased profitability to the user.

In 1975, when the company started developing its first generation Wire Rod Block, the experience and knowledge from the design and performance of these housingless stands was used. The Wire Rod Block roll units were designed with an optimum stiffness that, together with other unique design features, has been further developed to satisfy the increasing demands of the market. Morgårdshammar wire rod blocks are found where the rolling is toughest, stainless steels, nickel alloys, carbon steels and rebar are produced to the closest industrial tolerances.





General Design


The Morgårdshammar Wire Rod Block is supplied as 4, 6, 8, and 10 roll units for twist-free rolling. A primary gearbox drives the roll units via two common shafts. Two different sizes of roll units are available, with ∅ 170/150 mm rolls and ∅ 223/200 mm rolls. All roll units are identical and interchangeable. Morgårdshammar can offer blocks with different reduction ratios, such as 20%, 16%, or 14% average reduction per pass, depending on steel grades to be rolled. The block is designed for a speed of 120 m/s.





Quality, Efficiency, Economy


When using roller guides in high-speed applications it is a must to use air-oil lubrication. In the Morgårdshammar compact design lubricant is supplied from the guide adapter through the bottom of the guide. However, in such cases where it will not be possible to direct lubrication supply from the bottom, the guides can easily be changed to common supply from hoses via quick release couplings.

The lubricant is supplied via he pivot shaft and further through internal drillings to the bearings.

It is of highest importance that the bearings are shielded on the outside so that an overpressure is obtained inside the bearings to prevent water and residue from penetrating.


Examples of basic advantages:

Small space requirement hence easy to install
in existing plants
Easy removal and replacement of roll units for
inspection and maintenance
Excellent accessibility when changing
roll rings and guides
Simple roll-gap adjustment with safety cover down
Roll ring with radial stress free mounting for high
quality Tungsten Carbide rings
Unique feature for Stainless Steel applications
with intermediate shear inside the wire rod block






Stiff Roll Units For Close Tolerances


The power transmission to the rolls is unique. It is made directly to the roll shaft from the reduction gear over torsionally rigid, self-aligning couplings. This simplifies the design of the roll shafts and power transmission and means low maintenance costs. The design of the roll stand embodies direct transfer of the rolling load between the roll chocks. The large roll shafts and the short torque arm give unsurpassed stiffness and minimum deflection. This facilitates accurate setting of the roll unit before and during rolling and contributes to the best wire rod block rolling tolerances possible. The mill screws are supported in the roll chocks by the spherical mill-screw nuts. All play in the contact surfaces is eliminated by a pre-stressing system mounted integrally within each roll chock. The roll shafts are radially supported in friction bearings of multi-layer type eliminating any necessity to check bearing lift. The optimum hydrodynamic design of the friction bearing ensures stable running.

The roll shafts are axially supported in two opposing single-row, angular contact bearings. The roll shafts are driven via torsionally rigid couplings that allow the necessary angular alignment within the roll diameter range. Morgårdshammar offers a unique method for carbide ring mounting. The rolling torque is transmitted only by friction obtained by axial clamping at high pressure. No circumferential tension to the surface of the roll rings is present. Axial clamping makes it possible to use thin roll rings. Ring removal is by oil injection, which eliminates friction, scratching of the mating surfaces and expensive roll-shaft maintenance.





Roller Guides For Wire Rod Blocks


A recent development of the Morgårdshammar roller guides for Wire Rod Blocks is the SRW (Single Roller guide for Wire rod blocks) and the DRW (Double Roller guide for Wire rod block).


Characteristics:

Single-point central adjustment
Independent roller adjustment
Individual vertical roller adjustment
Critical parts made of stainless steel
Fully integrated supply of cooling and lubrication
without pipes from the Wire Rod Block



The bottom base of the guide is V-shaped in order to achieve a precise alignment between the guide and the attachment base. As an alternative to the SRW, where single-point central adjustment is not required, roller guide 0820 is recommended. The 0820 roller guide can also be supplied with V-shaped bottom base.

High-speed rolling requires maximum setting accuracy. For best results in setting, Morgårdshammar supply a high-precision optical equipment. Such equipment ensures proper alignment of the guide, in the guide shop and in the rolling mill.