What Is a Milling Machine?

Milling machine (milling machine) mainly refers to a machine tool that uses a milling cutter to process various surfaces of a workpiece. Normally, the milling cutter mainly rotates, and the movement of the workpiece and the milling cutter is the feed motion. It can process planes, grooves, and various curved surfaces, gears, etc.

The milling machine was first created by American E. Whitney in 1818

Distinguish according to layout form and scope of application

To be used for machining planes, steps,

Inspection standards

Mainly include: GB6477.9-86 "Milling Machine Terminology for Metal Cutting Machines", ZBJ54017-89 and JB / T5599-91 "Parameters and Series Profiles of Lifting Milling Machines", GB3933-83 "Milling Precision of Lifting Mills", JB / T2800- 92 "Technical Conditions of Elevating Table Milling Machine", ZBJ54014-88 "Accuracy of CNC Vertical Elevating Table Milling Machine", ZBJ54015-90 "Technical Conditions of CNC Vertical Elevating Table Milling Machine", JB3696-84 "Accuracy of Rocker Milling Machine", JB / T3697- 96 "Technical conditions for rocker milling machines", JB / T2873-91, JB / T5600-91 "Parameters and series of universal tool milling machines", JB / T2874-94 "Precision of universal tool milling machines", JB / T2875-92 "Universal tools Technical Conditions of Tool Milling Machines ", JB / Z135-79" Lathe Milling Machine Parameters and Series Profiles ", GB3932-83" Lathe Milling Machine Precision ", ZBJ54010-88" NC Lathe Milling Machine Precision ", JB / T3027-93" Longmen Milling Machine Parameters ", JB / T3028-93" Accuracy of Gantry Milling Machine ", JB / T3029-93" Technical Conditions of Gantry Milling Machine ", JB3311-83, JB / Z195-83" Plane Milling Machine Parameters and Series Spectrum ", JB3312-83" Plane milling machine accuracy ", JB / T3313-94" Technical conditions of plane milling machine ", ZBJ54013-88 "", JB / GQ "parameters of three-dimensional copy milling machine", JB / GQ "precision of three-dimensional copy milling machine", JB / GQ "technical conditions of three-dimensional copy milling machine", ZBJ54007-88 "accuracy of vertical three-dimensional copy milling machine", JB / T7414-94 "Technical conditions of vertical three-dimensional profile milling machine" and so on.

Inspection items related standards Inspection items and other

Special milling machine operating procedures

Applicable models:

1. Gantry milling machine: X245 (A662), X209 (6642), X2010, X2012A, FRM5, 6642H1, 92001.

2. Double-column milling machine: FX03, 564H1, 273-11A, 535H2, 459, 544H1, 571H1, 529H1, FXZ-001, 462C1.

Milling machines are mostly packed in wooden boxes.

XK-1060

Difference between milling machine and planer

Working scope of milling machine

1. Cleaning the bed and components, cleaning iron filings and the surrounding environment;

2. Check each oil level, it should not be lower than the oil level, and fill all parts with lubricating oil;

3. Cleaners, clamps and measuring tools.

Milling machine one guarantee operating range

1. Clean and adjust the workbench, screw handle and inlays on the column;

2. Check and adjust the clutch;

3. Clean the three-way guide rails and linoleum, and clean the internal and external parts of the motor, machine tool and accessories;

4. Inspect the oil circuit and fill each part with lubricating oil;

5. Tighten the screws.

Working scope of milling machine

1. Cleaning of the bed and components, cleaning iron filings and the surrounding environment, cleaners, clamps and measuring tools;

2. Check each oil level, it should not be lower than the oil level, and fill all parts with lubricating oil.

Milling machine weekend maintenance work range

First, clean

1. Disassemble and clean each felt pad;

2. Wipe the sliding surfaces and guide surfaces, wipe the workbench and the horizontal, lifting screw, wipe the transmission mechanism and the knife holder;

3. Wipe the dead ends of each part.

Second, lubrication

1. Each oil hole is clean and unobstructed and filled with lubricating oil;

2. Lubricate each rail surface and sliding surface and each screw;

3. Check the oil tank body and oil level of the transmission mechanism, and refuel to the elevation position.

Third, tighten

1. Check and tighten the pressure plate and the panel screws;

2. Check and tighten the slider fixing screws, the knife transmission mechanism, the hand wheel, the workbench bracket screws, and the fork top wires;

3. Check to tighten the loose screws in other parts.

Fourth, adjustment

1. Check and adjust the elasticity of the belt, pressure plate and inserts.

2. Check and adjust the slider and screw assembly.

V. Anticorrosion

1. Remove the rust of each part and protect the painted surface from collision.

2. Discontinued, grease the anti-corrosion of the guide rail surface of the standby equipment, the sliding screw handwheel and other exposed rusty parts.

Pre-shift maintenance

1. Check if there is no oil shortage in each oil tank before driving, and use clean engine oil for refueling as shown in the lubrication chart.

2. Check whether the appearance and function of the power switch is good, and whether the grounding device is complete.

3. Check whether the screws, eyes, handles, handballs and oil cups of each component are loose or missing. If found, tighten and fill in time.

4. Check the condition of the transmission belt.

Gantry milling machines are mostly made of steel or

The development of horizontal boring and milling machines has attracted much attention because of its concept of injection acceleration. Electric spindles, linear motors, and linear guides, which are technical support for high-speed operation, have been widely used, pushing the machine's operating speed to new heights. The innovative design of the spindle-replaceable horizontal boring and milling machining center solves the shortcomings of the advantages and disadvantages of the electric spindle and the boring rod mobile telescopic structure. Technical innovation.

The development of the floor-type milling and boring machine leads the trend of modern processing with its new design concept. The high-speed processing concept of the boring-shaft-free ram type and the use of a variety of milling head interchangeable structures show its style, which is a great alternative to traditional milling the trend of. Various milling head accessories represented by two-coordinate pendulum milling heads have become the main means to achieve high-speed and efficient composite machining. Its wider process performance, greater power, and greater rigidity are a major breakthrough in the development of floor milling and boring machines.

Although the CNC systems configured for various types of CNC milling machines are different, the functions of various CNC systems, except for some special functions, are basically the same. ^[3]

With the continuous development of science and technology, the requirements for the quality and productivity of mechanical products have become higher and higher, and the upgrading of products has continued to accelerate. Therefore, the transformation of CNC machine tools has become more important. Transformation has also become an important aspect of industrial development. Milling machines have a wide range of applications, mainly for machined or formed surfaces. When processing special planes such as arcs and cams on a vertical milling machine, it is necessary to rely on machine accessories such as circular tables and indexing heads, and to make overall adjustments to the machine. The processing accuracy is low, and the basic adjustment is laborious. Therefore, in order to improve the machining accuracy of the workpiece, ensure the quality of the product, and facilitate the processing of the arc surface and the curved surface of the cam, etc., the numerical control method can be used to transform the milling machine numerically.

Conditions for NC Transformation of Ordinary Milling Machines

Not all ordinary machine tools are suitable for NC transformation. The transformed machine should have the following conditions:

(1) The machine tool foundation must have sufficient rigidity

NC machine tools are high-precision machine tools and require high movement accuracy. Generally, the pulse equivalent of the closed-loop system is 0.001mm, and the pulse equivalent of the open-loop system is 0.005mm or 0.01mm. High positioning accuracy and contouring accuracy require that the basic parts of the machine tool have high dynamic and static stiffness. If the basic part is not rigid, it will easily deform after being subjected to force, and this deformation has a large uncertainty, and it is impossible to use CNC In the compensation function. Therefore, a machine tool with poor rigidity of the base part is not suitable for being transformed into a CNC machine tool.

(2) The reconstruction cost is appropriate and the economy is good

The cost of machine tool renovation is divided into machine tool and electrical parts. On the one hand, it is necessary to repair and modify the original machine tool part and replace worn parts; on the other hand, it is to replace the original machine tool control cabinet and replace it with a new numerical control system and strong electric device. The cost of renovation is related to how much the original machine tool parts are used, and also to what control system is used. Due to economic considerations, economical numerical control systems driven by stepper motors are usually used for machine tool transformation. How much the total cost of renovation is appropriate depends on the user. Generally speaking, it does not exceed half of the price of similar specifications of equipment, which is economically appropriate.

General steps of NC transformation of ordinary milling machine

(I) Mechanical part design

The most important part of the transformation of CNC machine tools is the transformation of the longitudinal and transverse feed mechanism and the design and control of the control system, so that it has a more reasonable structure and a more comprehensive control system, which is convenient for its actual application in practice. in production.

Feed motion of table

Because the plane is mainly used to process the curved contours of arcs and cams, the microcomputer numerical control is used to implement three-axis and two-axis linkage control. After the stepping motor is decelerated by the first gear, it is dragged by the ball screw nut pair. Because the load torque acting on the motor shaft is large during milling, a high-power stepper motor should be selected. The driving of high-power stepper motors is more difficult. The stepper motors do not have overload capacity, and the torque drops a lot during high-speed motion, and it is easy to lose steps. To make the feed servo performance of the milling machine better after the transformation, the DC servo motor is used for the transformation.

2. Structural design of mechanical part

(1) The original machine tool's spindle rotation motion is retained, and the table lifting movement is still manually operated. After the longitudinal and lateral feed transformation, both the computerized numerical control processing of complex parts can be performed by motor, and the simple parts can also be processed manually or used for Tool setting before CNC machining.

(2) Keep the motorized part of the longitudinal feed of the original machine tool, disengage the clutch, remove the handwheel, connect the handwheel shaft to the stepper motor through a pair of gears, and use the microcomputer numerical control system to control the longitudinal feed motion. During processing, the clutch is disengaged to stop the original motorized feed.

(3) For the horizontal movement of the table, a reduction gear and a stepping motor are installed at the original handwheel installation position, and the lateral feed movement is controlled by a microcomputer numerical control system.

(4) The DC servo motor is used as the driving element. The shaft end of the servo motor is the optical axis, the gear and the motor shaft, and the motor shaft and the transmission shaft adopt a cone-ring keyless connection to eliminate the connector structure. The characteristic of this connection is that no keyway is needed, and the relative angle of the two connecting pieces can be adjusted arbitrarily. Due to the wedge-tightening effect between the cone rings, the inner and outer rings are deformed elastically in the radial direction, and are connected to the sleeve by friction to eliminate the fit clearance and ensure centering.

(Two) hardware design of numerical control system

The numerical control part adopts MCS-51 series 8031 single-chip microcomputer to realize the main control of the whole system. Using 8031 external 3 pieces of 2764 (E-PROM), a piece of 6264 (RAM) and a piece of 8255 (expanded I / O), a piece of 8155 chip, expand into a simpler computer control system. 2764 is used as program memory, 6264 is used to expand the RAM memory of 8031, 8155 is used as a keyboard and display interface, and 8255 is used to receive the control signal of the multi-way switch on the control panel. Figure 2 is a schematic diagram of the hardware structure of the control system. When the single-chip microcomputer system controls a single stepping motor of the X and Y axes, the horizontal and vertical linear feed of the milling machine can be realized; when the XY axis is controlled to cooperate with the linkage, it can realize straight lines, oblique lines, arcs and composites in the horizontal plane The processing of the trajectory can approximate the non-circular curve in the horizontal plane. Based on the original machining function of the milling machine, its control accuracy and machining accuracy are much higher than ordinary milling machines.

Milling machines unavailable for two types of foundry companies announced by AQSIQ

The General Administration of Quality Supervision, Inspection and Quarantine conducted spot checks on 30 types of milling machines in 10 provinces and cities including Zhejiang, Fujian, Jiangsu, Shandong, Jilin, and Liaoning. According to the requirements of the General Technical Requirements for Safety Protection of Metal Cutting Machine Tools GB15760-2004, Mechanical Electrical Safety Machinery Electrical Equipment Part 1: General Technical Conditions GB5226.1-2008 and other standards, after inspection, two of the milling machines are not Qualified, so this type of product is not suitable for foundry companies.

The radial drilling machine manufactured by Tengzhou Dongfang Machine Tool Co., Ltd., tested by Zhejiang Quality Inspection Scientific Research Institute, has the model ZQ3040 × 12. The reasons for this product's failure are: emergency stop, splash, and motor overheating protection are not satisfactory. Zhejiang Shuanglong Machinery Co., Ltd., a dual-use drilling and milling machine tool produced by the Zhejiang Quality Inspection Scientific Research Institute, is named Qilong and its model is ZX7020. After testing, its products have been tested for emergency stop, splash, power switch, overcurrent protection, accuracy Aspects are not qualified.

Milling machines are often used in foundry companies for surface treatment of cast products. The above two types of products are unqualified, and the General Administration of Quality Supervision, Inspection and Quarantine recommends that casting enterprises do not use them.

Concluding remarks

The NC transformation of the ordinary milling machine is essentially adding a microcomputer control device to the ordinary milling machine so that it has a certain degree of automation capability to achieve the predetermined processing technology goals. The purpose is to make the original machine tool have certain flexibility, improve production efficiency and quality, and solve the processing problems of complex parts. The single-chip microcomputer expansion system is used to transform an ordinary milling machine into an economical milling machine, which is simple and easy to implement, can guarantee the machining accuracy of parts, and has a significant effect on the machining of complex parts, especially curved surfaces and convex surfaces.