Fine turning and roller burnishing machines

HEGENSCHEIDT 7794 - Fine turning and roller burnishing of crankshafts

The 7794 is a universal fine turning and roller burnishing machine for machining the end faces of crankshaft thrust bearings. The bearings are fine-turned and smoothed to the required length references. The precision turning operation significantly improves the parallelism of the flat surfaces due to the high machining accuracy and machining tolerance. The subsequent roller burnishing process significantly increases the contact ratio of the flat surfaces and results in very good running properties.

Areas of use and application

The 7794 is a universal fine turning and roller burnishing machine for machining the end faces of crankshaft thrust bearings. These are reliably fine-turned and smooth-rolled, taking into account the required length references. The fine-turning operation considerably improves the parallelism of the flat surfaces due to the high machining accuracy and machining tolerance. The subsequent smooth rolling significantly increases the contact ratio of the flat surfaces and leads to very good running properties. During machine development, the focus was on short machining times and long tool life for both the fine turning tool and the roller burnishing tool. With the 7794U-2NC model, the flange face, the encoder ring, etc. can also be machined using an additional NC-driven cross slide. As the additional machining is carried out in one and the same clamping operation as the machining of the locating bearing, optimum axial production tolerances are achieved. This additional operation drastically reduces investment and production costs, as a complete subsequent operation can be replaced.

Added value

Fine turning and roller burnishing replace conventional processes such as grinding and polishing
Excellent surface quality
Increased contact ratio of the flat surfaces (no aggressive peaks)
Improved fine hardness
Dry machining
Turning of various materials
Long tool life
High machine availability
Short floor-to-floor times
High production reliability
Low process and tool costs
Low maintenance and production costs
Low energy consumption
The possibility of machining the mating bearing and flange eliminates the need for an additional machine for flange machining alone

Function

The crankshaft is loaded and unloaded from the loading gantry through the loading hatch and deposited on pre-supports in the machining position. The floating quills are clamped hydraulically to clamp the workpiece. The measuring device is moved forward to scan the position of the shim bearing shoulders via the measuring sensor. The recorded coordinates are transmitted to the NC axis for positioning the machining units in cross slide I and, if necessary, cross slide II (7794U-2NC). The locating bearing shoulders are then fine-turned one after the other. In addition, the flange, encoder ring seat, etc. can be machined with the 7794U-2NC via cross slide II. can be machined. After the turning operation and before roller burnishing, the width of the locating bearing is measured again and any correction values are passed on to the control system for the next machining operation. The quill clamp is released for the roller burnishing operation. The register bearing smoothing device is moved forward to the machining position. The oil coils are now rolled smooth to increase the contact ratio and create a functional surface with Ra ≤ 0.4µm.

The machine and all additional units form a compact unit. This keeps transportation and assembly costs on site to a minimum. The tailstock, the cross slide with facing support, the roller burnishing unit with measuring device and the optional additional support for flange processing are mounted on the machine stand, which is designed as a welded construction. The ergonomic control panel with all the necessary operating elements can be swiveled.

Highlights of the 7794

Machine specification

	Types 7794U-1NC and 7794U-2NC
Machine data
Machine dimensions (L x W x H)	4,000 mm x 3,000 mm x 2,500 mm (including integrated control cabinet and hydraulics)
Machine weight	5,5 t
Machining height	1,250 mm
Connection data
Installed electrical power	30 kVA
Compressed air connection	1/2 inch
Required connection pressure for compressed air, min.	0.6 MPa
Compressed air consumption	~ 10 m³/h
Machining speed
Cutting speed when turning	~ 170 m/min
Rolling speed	~ 45 m/min
Workpiece data
Length, min. \| max.	260 mm \| 700 mm
Vibration diameter max.	220 mm
Bearing width min. \| max.	18 mm \| 70 mm
Bearing level max.	12.5 mm
Additional equipment type 7794U-2 NC
	Additional longitudinal slide for: Fine turning of the flange face Fine turning of the flange diameter Fine turning of the flange journal Grooving the flange journal Fine turning of the shaft journal diameter

Brochure

Here you will find all the contents of the 7794U as a download.

DOWNLOAD | PDF 3.85 MB

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