The quality of processing often depends on the correct location of all structural elements. Choosing the right mechanism in accordance with all standards and tolerances is quite difficult. An important element in the design of metal processing equipment can be called a coordinate table. It is used when processing on drilling, milling equipment for precise positioning of the workpiece during processing.
Hardware Definition
A coordinate table is a manipulator that is used to secure the workpiece being processed. There are several options for machine tables:
- vacuum fastening method - used quite rarely due to the complexity of the design;
- the mechanical type of fastening is simple to implement, you can do it yourself quickly;
- fastening due to the weight of the workpiece. Using drilling machine Large workpieces can be processed. Due to its weight, the supported part remains in place even under strong impacts.
There are positioning with one, two, three degrees of freedom. This point determines that the workpiece can be fed along three different coordinates. When drilling a flat product, it is enough to move it along just one horizontal plane.
We can roughly distinguish two main types:
- Large dimensions. A large coordinate table is created taking into account the fact that the equipment itself, as well as the workpiece, will be installed on it.
- Small coordinate table overall dimensions mounted on the equipment frame.
There are several control mechanisms by which the coordinate table changes its position:
- Mechanical drive is quite common. You can make it for a drilling machine with your own hands to set up small-scale production.
- An electric drive is installed quite often for a drilling machine. Making it yourself is quite difficult, since you need to maintain high precision during manufacturing. For automatic movement, the coordinate table must have its own power source.
- Another separate group can be called a mechanism that operates using numerical control.
You can make a small coordinate table with a mechanical drive with your own hands.
Production of homemade versions
When manufacturing, you should initially select the material of manufacture:
- Cast iron is expensive, heavy, brittle material. It is quite rarely used in the production of a drilling machine.
- Steel is a strong, hard, durable metal, which also has a fairly high cost. Steel can be called the most attractive material.
- Aluminum is a light, fusible, but expensive and soft material. It is quite easy to use in the manufacture of any machine parts. As a rule, mini equipment is created using this alloy.
The above materials are selected for a full or mini machine.
Manufacturing of guides
The accuracy of processing depends on the correct choice of guides. You can make the following designs with your own hands:
- rail;
- cylindrical.
They are created with a carriage and bearing units. You can select guides depending on the type of drive. To achieve the highest processing accuracy, plain bearings are used. When using a rolling bearing, friction is significantly reduced and the service life of the device is increased, but significant play appears, which reduces the accuracy of processing.
There are two types of guide carriage:
- with increased flange dimensions, which allows mounting from below the table;
- the design without a flange is attached from above using the threaded method.
Let us note the point that homemade version execution of the guide should be closed using of stainless steel. Stainless coated steel can withstand impact high humidity for a long time.
Drive types
When creating a small machine, a coordinate table with mechanical feed is often installed. However, there are quite a few types of drives, the selection of which is based on the following criteria:
- processing speed;
- positioning accuracy;
- equipment performance.
In most cases they choose electric drive, during the creation of which an engine is installed.
The essence of this mechanism is to convert rotation into reciprocating motion. The following types of gears are distinguished for the design in question:
- belt;
- ball screw;
- rack and pinion.
When creating a drive, a belt drive is often chosen. Homemade mechanism The belt type is cheaper than others, but the belt quickly wears out and stretches. Also, belt slippage determines the low accuracy of the moving element. All elements of the coordinate steel are connected to each other by welding. In this case, the threaded method of connecting certain parts is also used.
In conclusion, it should be noted that homemade design Suitable exclusively for equipment household use, since it is practically impossible to achieve the accuracy that industrial models have.
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The coordinate table helps to make the operation of the unit precise, smoothly move the workpiece to the desired position, and avoid jumps and twisting of the part. The efficiency of working on any type of machine increases significantly when using a coordinate table, especially one made by yourself.
A coordinate table makes drilling faster, easier and more accurate. If a person has a set of tools and materials on hand, such equipment is easy to do independently.
Types and purpose
Tables for drilling machines come in several different types and can be made from various materials and operate on different principles. This is a simple fixing device, with the help of which the workpiece is secured in the required position.
With the help of a table during processing, a part is able to change its position and angle; manipulation allows different types processing without removing or moving the part. The methods for fixing equipment are as follows:
- using vacuum and differential pressure;
- mechanical devices;
- the part is held on the table independently due to its heavy weight.
For amateurs who are planning to make a table for a drilling machine with their own hands, the second fixation option is most suitable.
Workpiece to be fixed in different installations has an unequal number of degrees of freedom - two or three. In the first case, she is able to move only along the X and Y coordinates; in the second, the ability to move up, down or along the Z coordinate is added. For home use two degrees of freedom is quite enough.
Equipment use
Before starting to operate the coordinate base, the master must study the safety rules, equipment features, as well as the lighting requirements in the room where the work is taking place.
The table is activated in the following ways:
- mechanical movement;
- use of electric drive;
- installation .
The first or second option, if you implement it yourself, will be the most suitable.
It is worth mentioning separately such design options as Rotary table and cross.
The first one is capable of rotating around its own axis and is the maximum convenient option, if you need to process parts with axial symmetry, round and disc-shaped workpieces.
The cross drill table is more common in everyday use and provides the ability to move the workpiece in two directions: X and Y.
Base material
Before you start creating a device, you need to think about what materials and spare parts to use. Preliminary preparation necessary so that they can give the future creation the following characteristics:
- Normal working weight so that one person can work with such a table without noticeable difficulty.
- Simplicity and versatility of installation. Good product must fit different types drilling equipment.
- Maximum cost savings on manufacturing. If development turns out to be too expensive, wouldn’t it be easier to buy a ready-made item?
Most often, these requirements are met by the following common and economical options:
- steel;
- metal;
- cast iron;
- aluminum;
- duralumin.
If the table is needed mainly for drilling soft materials(wood, plastic), then aluminum would be the best option. It is extremely light and has sufficient strength.
If you have to work with metals, drill serious parts to a relatively large depth, then you will need something more durable - steel, cast iron, iron. These are heavy materials, but the loads they can withstand are impressive.
Guides
Of particular importance in the design of the device being developed are the so-called guides - components along which the table moves in the required directions.
The better they are made, the more accurately the specialist will work on the machine, set the position of the workpiece being processed and the easier it will be to move it in Right place, apply filler materials and perform other necessary actions.
Two types of guides are used: cylindrical type and rail type. It’s difficult to say which of them is more efficient - with high-quality implementation, both options perform well.
To make the sliding of the guides as smooth and accurate as possible, it is necessary to use special carriages and bearings. If the requirements for the accuracy of the equipment are not too high, then rolling bearings are quite suitable, otherwise, plain bearings must be used.
Roller bearings will create a slight amount of play, but for typical applications this is not a major problem.
For smooth sliding of the guides, it is possible to use rolling bearings
When making a product with your own hands, you need to choose the option that is most suitable for future tasks.
Motion transmission mechanism
The most important part of the future device, no matter whether it is a rotary table for a drilling machine or a cross version, is the mechanism for transmitting movement from the control handles to the device.
It is best to make a drive with mechanical type movements are manually controlled. In this way, specialists can achieve greater accuracy of movements, High Quality work being performed.
The components of the motion transmission mechanism are:
- racks and gears, gears;
- belt mechanisms;
- ball screw drives.
Experts advise choosing the latter type of mechanism, especially if we're talking about About the cross table, it has many significant advantages:
- extremely small system play;
- the product moves very smoothly, without jerking;
- The ball screw operates quietly;
- under significant workloads it shows high stability.
Experts say that the disadvantage of the mechanism is the inability to achieve high operating speed, but if you are considering a cross table for a drilling machine, then high speed is usually not required.
To save money, the master needs to try to implement belt drives. They are simple and accessible, but have disadvantages:
- low accuracy;
- rapid wear;
As a conclusion, we note that if a person decides to make a table for a drilling machine with his own hands, then there is nothing fundamentally unrealistic about this. A basic set of materials and tools will help you quickly complete the task. The task for the specialist is to choose correct view design and high-quality production of all critical components of the future device.
Of great importance when operating drilling equipment are additional accessories, making the operator’s work more convenient and efficient. Thus, a coordinate table used to equip a drilling machine significantly increases the productivity of the device and the accuracy of the processing performed. This device can be purchased from finished form or do it yourself.
Purpose and types
In essence, a coordinate table is a movable metal platform on the surface of which a workpiece processed on a machine is mounted. Possible various ways such fixation:
- using mechanical devices;
- by means of vacuum;
- due to the own weight of massive parts.
Depending on their functionality, coordinates can have two or three degrees of freedom. So, individual models can only move in the horizontal plane (X and Y axes), while more technologically advanced ones can also make vertical movements (Z axis). Tables of the first type are used when processing flat parts, and devices with the ability to move vertically are equipped with drilling machines that process parts with complex configurations.
On large industrial enterprises where large-sized parts are processed, long coordinate pads are often used, on which, thanks to the presence of a special mounting frame in their design, both the workpiece and drilling equipment can be installed. Most of the models are mounted on the machine itself or on the surface of a workbench.
They can be responsible for moving the coordinate table different kinds drives:
- mechanical;
- electric;
- equipped with a CNC system.
Warping characteristics
Coordinate-type tables, which are equipped with drilling machines, can be made with bases made of various materials:
- cast iron;
- become;
- light alloys based on aluminum.
Tables with base made of aluminum construction are not designed for heavy loads, so they are used to equip drilling machines that process parts made of soft materials (wood, plastic). The advantages of devices whose frame is made of aluminum profile are:
- light weight;
- ease of installation;
- affordable price.
Thanks to the simplicity of its design and the availability of manufacturing materials, such a table is easy to make with your own hands. If you don’t want to use it while working on the machine homemade device, you can purchase a ready-made kit for its assembly, which is produced by many companies.
Industrial coordinate tables for drilling machines, which are used most intensively and experience significant loads during operation, are manufactured with bases made of cast iron.
Both serial and homemade tables coordinate type can be manufactured on the basis of welded steel frames, which demonstrate high reliability. When making such a frame with your own hands, you should keep in mind that welded joints do not withstand vibration loads well, so in the finished structure it is necessary to get rid of internal stresses as much as possible. This is achieved through appropriate heat treatment (tempering).
Coordinate tables, depending on their purpose, can be made according to two design schemes:
- crusade;
- portal
Tables made according to the first scheme are equipped with universal drilling machines, on which parts of complex configurations are processed. The design features of such devices allow access to the workpiece being processed from three sides. Portal-type tables are equipped with machines on which holes are drilled in sheet blanks.
Guides
The guides along which the coordinate table moves are important element its design, since from their quality and design features Not only the smooth movement of the part depends, but also the accuracy of its processing. Both in serial models and in homemade coordinate tables, the guides can be of rail or cylindrical type.
Smooth and accurate movement along the guides is ensured by the built-in carriage and bearing units. In cases where increased movement accuracy is required from the coordinate table, sliding bearings are used in its guides, since rolling bearings create significant play in the supports, although they reduce the friction force more effectively.
Guides for coordinate tables, depending on the type of carriage, are:
- equipped with an enlarged flange used to attach the structure to the bottom of the table;
- wafer-type, which are fastened in the usual way.
Dovetail guide
Mechanisms for transmitting motion
On the simplest models of serial drilling machines and on equipment that is made by hand, coordinate tables are installed mainly, which are driven mechanically. In the event that the drilling machine is required high accuracy and processing performance, tables driven by electric motors are installed on it.
Three types of gears are used in coordinate table drives:
- based gear wheels and slats;
- based on belt mechanisms;
- ball screw.
The choice of transmission type is influenced by a number of parameters:
- the speed at which the table and the workpiece attached to it must move;
- power of the electric motor used;
- requirements for precision processing of parts.
High precision of movement is ensured by a ball screw drive, which also has a number of other advantages:
- very slight play;
- smooth movement;
- quiet operation;
- resistance to significant loads.
Ball screw in high precision coordinate table
The efficiency and accuracy of part processing largely depends on the quality of the machine. A correctly selected mechanism is the key to product compliance with all specified standards and tolerances. An important role in compliance with drilling technology is played by a coordinate table.
Concept and types
The table is a manipulator for fastening the workpiece being processed. Externally, it looks like a plate with the ability to fix the part using:
- mechanical method;
- vacuum method;
- own weight of the workpiece.
Products come with one, two and three degrees of freedom. This means that the feed is carried out along the coordinates X, Y, Z. For drilling flat parts, horizontal movements are sufficient. With a voluminous product or a fixed drill, vertical movement of the table is necessary.
For large industrial drilling installations, long coordinate pads are manufactured. They are equipped with their own mounting frame. Both the part and the processing unit itself are mounted on such a device. The table for small machines is made with fastening to the device or to the surface of the workbench.
To set the table in motion, the design can be:
- mechanical;
- electrical;
The latter type is the most accurate, but the cost of such a device is significant.
Manufacturing of load-bearing elements
The materials for making the table frame are:
- cast iron;
- metal;
- aluminum.
The latter material is used for circuits with light loads and low torque forces. This option is acceptable when drilling wood or plastic.
pulled aluminum profile frame, mounted on threaded connections. This creates a solid foundation. Advantages of the material:
- low weight;
- accessibility;
- ease of installation.
Many companies produce ready-made kits for assembling tables with your own hands.
Cast base structures are often cast iron. Their weight is significant, but the forces they can withstand are quite high. Such tables are used for large production volumes. Installation is carried out on the foundation, permanently.
The welded frame is the best option both for production facilities and for home use. The main thing is to reduce the welding stresses of the metal by releasing it when welding with your own hands. Otherwise, when the engine picks up speed, cracks may appear in the frame.
For drilling machines, two table technological schemes are used:
- cross;
- portal.
The first is used for bulk workpieces. It makes it possible to carry out other manipulations on the fixed workpiece. With this arrangement, access to the part is provided from three sides.
The portal pattern is used when drilling flat products. It is easier to manufacture and has increased processing accuracy.
Selection of guides
From the right choice and fastening the movement guides of the table surface depends on the accuracy of processing. Rail and cylindrical elements are used. They are produced with a carriage superstructure and mounted bearing units.
The choice of table guide type depends on the type of drive. The part in question works to overcome the friction force. If high precision in movement is required, it is better to choose plain bearings. Rolling bearings reduce friction but create a lot of play.
Depending on the type of carriage, the guides are:
- with an enlarged flange, for fastening to the bottom of the table;
- Wafer type for conventional mounting to top threaded holes.
If you make it yourself, you can order rails with a stainless steel coating. They have an increased service life and longer abrasion resistance.
Types of gears for table movement
With small desktop machine The table is moved mechanically. But the greater the speed, accuracy and performance required, the more carefully the type of drive is selected. Electric motors are mainly used.
The essence of the unit’s operation is to convert the rotational work of the engine into translational motion of the table plane. There are three types of transmissions:
- rack and pinion;
- belt;
- ball screw.
The choice of node type is made based on:
- workpiece movement speed;
- machine engine power;
- required processing accuracy.
Machining accuracy at various transfer units
Advantages of Ball Screw:
- possibility of high-precision processing;
- small backlash;
- smooth movement of the table;
- quiet operation;
- ability to take heavy loads.
A significant disadvantage is the limited feed speed. The decrease in speed is especially noticeable when the propeller length is more than 1500 mm. Approximate speed calculation: for a 1 kW drive, the rotation speed is 3000 rpm. With a screw pitch of 10 mm, the transmission speed is 0.5 m/sec. In this case, 3 m will be covered in 6 seconds.
Another disadvantage is the high cost. You can reduce the cost of the project by using a connection with a screw and nut. In this case, it is necessary to ensure constant lubrication of the unit.
In new generation drilling machines, lubrication of the movable mechanisms of the coordinate surface is carried out automatically. The device contains sensors for monitoring the temperature of important parts.
The rack and pinion transmission ensures high speed and sufficient accuracy. The disadvantage is the high degree of play when transmitting forces from the drive.
Installing a belt is the most budget-friendly and common method when creating a table with your own hands. The low cost of belt drive and feed speed up to 1 m/s is compensated by the following disadvantages:
- rapid wear;
- loss of tension due to stretching;
- possibility of breakage during acceleration;
- low accuracy of work.
When purchasing a coordinate table for drilling or do-it-yourself installation, you must take into account the working conditions. The ratio of all mechanisms according to parameters: workload, service life, heating and cooling will give good result at work. This is especially important when self-production from scrap materials.
Modernization of a metal-working milling machine will increase the technical potential and significantly expand its productive capabilities. One of possible options modernization consists of installing on milling machine coordinate mini-table. By using a jig table for the milling unit, the manufacturer can significantly reduce labor intensity.
Characteristic
The coordinate table device is an additional structure to the machine that allows you to move the part fixed on it along the required path. The installation can be used both for a milling unit and for a drilling unit. There are two types of coordinate table - industrial factory or small homemade.
The table can be set in motion using mechanical action manually, using electric drives or using computer control systems. When using numerical control, production is as automated as possible, and the processing accuracy of the part varies in the region of several micrometers.
Variety
In the factory version, the coordinate part installed on a milling or drilling machine includes:
- load-bearing support;
- control drives;
- part fixation system;
- automated control system.
Part fixation is divided into three types:
- vacuum;
- using the mass of the part itself;
- mechanical.
Coordinate structures have several different designs, but there are two main ones:
- portal;
- cross.
The cross pattern is used for processing volumetric parts, which is solved by using additional structures with three degrees of freedom. This means that the workpiece being processed has the ability to move along X, Y, and Z coordinates. In this design, the coordinate structure is installed on a milling machine.
The gantry scheme is a rotary table that is used to work with flat parts, in particular for drilling, with a rigidly fixed working body when movement along a vertical axis is necessary.
At enterprises producing large-sized products, long coordinate aluminum structures are installed. Thanks to this, the functionality of the machines used increases, because on the workbench it is possible to secure equipment, such as:
- special connector for tools;
- cooling drive;
- lubrication drive;
- neutralization of harmful gases and fumes;
- drive for removing dust and chips.
Features of the supporting structure
The design of coordinate settings for a milling machine and a machine differs in the material from which it is made Basic structure. If these are massive metal parts, then it is necessary to use a more rigid structure, which may consist of cast metal.
More rigid structures are still used to ensure the necessary clarity of movement of the working object on machines with, since the speed of movement of the workpiece in such production can reach several meters per second.
The material used for the manufacture of coordinate mounting pads is chosen as follows:
- steel;
- cast iron;
- aluminum alloys.
Structures consisting of aluminum alloys, are designed for light loads and are often used to equip drilling machines, where only vertical movement of the workpiece is implied.
The advantages of such a device are:
- manufacturability;
- budget;
- low weight of the structure.
Mechanisms for transmitting motion
Factory and homemade coordinate mini-platforms are driven mechanically. If production is associated with high-precision processes, then in such cases electric motors are used.
Types of gears for converting rotational motion into translational motion, as well as for moving a part relative to the working element, are divided according to the method of implementation.
They are divided into:
- gear;
- belt;
- screw.
Parameters that influence the selection of transmission type:
- the speed of movement of the platform with the workpiece fixed on its surface;
- electric motor power;
- processing accuracy.
The best option in terms of efficiency and ensuring the accuracy of movement of the part is a ball screw, which also has a number of other features:
- no jerking when moving;
- no noise;
- small backlash.
One of the disadvantages of this type of transmission is the inability to move the coordinate table from high speed. The second disadvantage is the high cost.
High cost is one of the disadvantages of this transmission
Additional options
It will be cheaper to use a belt drive, but as the cost decreases, the disadvantages also increase:
- increased wear;
- the need for frequent maintenance;
- high probability of belt breakage;
- low accuracy.
High accuracy and rapid movement of a part on a fixed platform can be achieved by using a gear drive, but in such a mechanism you need to be prepared for the appearance of backlash some time after the start of operation.
One of best options transmitting motion from the engine to a mini-coordinate unit is the use of a direct drive, which consists of:
- linear motor;
- servo amplifier.
Servo amplifier
The advantage of these drives is that there is no need to use mechanical transmissions. This design allows you to directly transfer movement from the engine to the elements of the coordinate table.
The benefits also include increased speed and accuracy of part processing. Due to the fact that there are no auxiliary gears in the table circuit, the number of series-connected elements is reduced, and this, in turn, in better side affects the reliability of the coordinate installation.
conclusions
The error, which is at the level of several micrometers, is noticeably reduced in relation to other types of gears. Direct drive is characterized by high braking and acceleration rates.
Due to the fact that there are no parts in the direct drive that are subject to friction, the aluminum coordinate unit is less subject to wear, which has a positive effect on its durability.
One of the few, but most significant disadvantages of direct drive is its price. The high cost of mass high-precision production is justified and paid off.
