Band saw welding technology at home. necessary equipment, mode, control
Saw blades are widely used in the woodworking industry, the main feature of which is a continuous cutting surface. It is a ring of band with metal teeth.
Band saw welding is at the heart of their manufacture, as they are obtained by joining a pre-prepared band into a ring. This process is also used in their repair. This article will talk about the main features of welding such devices.
General information
When joining the band saw ends it is necessary to consider the stresses to which the band is subjected during the processing of the workpieces by subjecting it to constant stretching and bending.
Made of alloyed or carbon steel band saw strip withstands the force of the processed material, which sometimes cannot be said about the welded joint.
After a period of hours worked, the weld breaks. That is why the latter must be made of a material of the same composition as the toothed ring itself.
Use of a special machine for band saws welding, which uses contact arc welding, will help to create a quality joint.
The latter is due to uniform heating of the joints of the two parts to be joined. After the described thermal process, the ends meet tightly to form an inseparable ring.
Band Saw Welding Machine
Band saw welding works on the principle of resistance and fusion welding. This equipment is designed for a wide variety of welding jobs, as well as a variety of activities.
Machine for saw welding is divided into several groups:
- Resistance welding is an affordable welding machine that is designed for wood saws and their repairs, for example, in the production area when sawing wood. This machine is designed to be easy to use, but it has a low productivity, only about a hundred welding jobs for a whole shift.
- Welding by means of melting is made when using the medium variant of the equipment, which is designed for welding knives and saws of any varieties, the load here is rather large in comparison with the above-described equipment.
- Welding by means of melting automatic welding cycle allows to weld various saws and blades quickly, and this equipment has a high productivity, allowing for one shift to produce up to thousands of welds. This method is usually used in centers and services, as well as in manufacturing plants.
There are also other devices that are auxiliary in order to prepare and monitor the welding process:
Welding operations
Bandsaw welding is subdivided into several steps. For each technological step, it is necessary to strictly follow the methodology to achieve the best result.
There are several types of devices that allow the process of joining. They generally function as follows: the edges of the saw’s ends are joined together by welding them together and passing current through them.
Such equipment is excellent for small amounts of work, it will be especially effective in the repair of saws of production sawmills.
This method requires high quality preparation of the joint and electrodes, as well as the right choice of modes. Devices that operate on the principle of melting offer higher productivity. In addition, they are able to work with all types of blades. Such devices are in the middle class.
The method also requires good preparation of the surface, the right choice of modes and accounting of metal consumption.
Automatic devices, working on the technology of melting, require from the machine operator only the installation of quality materials, as well as their removal after the completion of processing. This tool is widely used in professional workshops and service centers.
The saw welding process, as noted above, is divided into stages, each of which will be described below.
Cutting
In addition to the machine for saw welding, some other tools are required. These include guillotine shears, used to cut the blade. If you don’t have such a device, you can use a chisel or a cutting machine.
If the connection is made in a previously used area, five millimeters should be cut off on each side. The cut must be made perpendicularly between the teeth. On each side an allowance of five millimeters is left.
Deburring
Welding a band saw. The next step is to clean the saw blade. To this end, it is necessary to carry out a thorough cleaning of the surface of the tool. As solvents you can use acetone or alcohol.
In addition to dirt, burrs and irregularities must be removed. This is easiest to do on the sharpening machine.
Installing
After preparing the blade according to the steps listed above, the blade is placed in the welding equipment. Edges of the product must match each other.
Equipment parameters such as force, mode and stroke are set based on the material selected for the blade. You can find the necessary regimes in the tables in the documentation of the machine.
Welding
If professional equipment is used, the butt welding of band saws is started by turning the appropriate knobs or by pressing a button. Current is applied to the electrodes, passes through the joint, heats the metal to melting point, and joins the ends of the blade together.
One of the essential parameters is the current time. In automatic equipment it takes one or two seconds. If welding is done by your own hands. the time is set by the master.
Annealing
Band saw preparation processes. Immediately after making the connection the saw is not usable. To prepare the tool at the application it is necessary to perform a few more operations with the blade.
Welding machine makes the saw material brittle. It becomes impossible to use it in operation. This problem can be solved by annealing. This process is carried out by passing a smaller current through the product. As a result, the seam is heated, and then it is cooled.
You can control the temperature of the annealing with a pyrometer. If it is absent, control is carried out visually by the color of metal. A cherry red is the best color, but orange or yellow indicates overheating.
Sharpening
The final step is to clean the connection from the accumulated metal. It is also necessary to bring the correct shape of the cavity between the teeth. Any type of abrasive can be used for this purpose. However, as mentioned earlier, it is best to use a sharpening machine.
What materials and tools will be required to make the saw
Set of tools and supplies for creating a band saw with their own hands at home can vary depending on the features of the chosen design. But, as a rule, it is obligatory to construct a machine:
- Boards or sheets of plywood for the frame;
- bearings;
- motor. electric or gasoline motor;
- metal corners;
- metal cutting blade. homemade or purchased;
- self-tapping screws and bolts with nuts;
- rubber from a bicycle camera;
- wooden bars and slats, they are needed for the supporting frame of the structure;
- grommets;
- belt to transmit the torque;
- steel rod, which will serve as a shaft for the pulleys
- steel plate or a piece of textolite;
- varnish or paint, they are needed at the final stage of the construction of the machine.
READ How much quieter does a cordless chainsaw sound?
Also, when making a band saw with your own hands, you will need to use the following tools:
- angle grinder;
- electric screwdriver;
- pliers;
- wrenches. sizes are chosen according to the bolts;
- electric jigsaw;
- screwdrivers;
- hammer.
How to assemble a band saw from a jigsaw with your own hands
Another simple scheme suggests making a mini band saw on wood with your own hands from an electric jigsaw. The algorithm is as follows:
- Place the jigsaw on a small square workpiece with the handle facing down and secure the metal corners on both sides. Using a drill in the marked places make holes for screws. Fix the squares on the wooden base. Suitable base for the bench-mounted jigsaw is any hard board or small chipboard
- Between the corners insert the jigsaw, lift it slightly and put a piece of rubber between the edge of the metal elements and the body. Since the tool is not pressed closely to the board, there is space at the bottom to make adjustments through the buttons. Use long screws to fix the jigsaw between the nooks so it won’t wobble or play. The rubber gasket cushions any vibrations that may occur when the jigsaw is operated
- Theoretically a semblance of a band saw can already be used, but it is more convenient to perfect the construction and give it the appearance of a classic machine. To do this, a compact-sized tabletop is attached to the sole of the jigsaw with screws. Preliminarily it is necessary to cut a narrow hole in it, through which the band saw blade of the tool will protrude. For a table top any hard material will do. steel, textolite, ebonite
For serious work and cutting logs and large boards a band saw
from an electric jigsaw with your own hands is not suitable. But it will be very handy for small workpieces with its help.
Choice of band saw blade
If desired, you can make a saw blade for the band saw with your own hands from tool steel U8 or U10. The material must be strong, but flexible, with a thickness of 0,4-0,8 mm for sawing hardwood. With an independent creation of the blade you will need with the help of an angle grinder to cut teeth in the metal, dilute and sharpen them, and then solder the band in a solid ring with a gas burner and grind the seam.
Soldering
When the contact method of welding is not available, use high-temperature soldering with silver solder and a special paste flux based on borax. To fix the ends of the blade, a simple homemade device is used. Heating is done with a gas torch.
Soldering is performed according to the standard procedure. Flux is applied to the beveled ends of the saw. After clamping in fixture joint place is heated to the melting point of solder laid nearby. Under the action of capillary forces it will begin to tighten into the joint. After solder appears all along the joint line heating stops. After the saw has cooled, it is removed and cleaned from the buildup.
Welding and soldering band saws: how to do everything correctly with your own hands?
Band saw. a special fixed closed blade with teeth, designed for sawing metal, wood products on special machines. When working, they sometimes break as a result of the increased load. After that the saw can be thrown away. But if it is not worn out, you can try to repair with your own hands.
The band saw blade is subjected to high stress in operation, which can sometimes tear it. The repair seems simple. The challenge lies in the quality of the connection. The weld must be able to withstand the same loads as the product itself, which is subjected to bending and tensile stresses.
Welding the band saw blade is the best choice. It can be securely joined with a special band saw welding machine. It welds the saw butt to butt, after which its performance is not impaired. It is not possible to do such a job with manual resistance welding.
Welding machines differ only in degree of automation. Some use manual welding and seam control, the advanced ones do everything automatically.
The simplest machine requires a few preparatory steps:
- Cutting of the blade. To do this, we use a guillotine. it gives the smoothest cut. It is placed on the top of the teeth, leaving 1-2 mm for the draft. It is better to process the ends simultaneously, folding the cloth, for even processing.
- After the cut, the ends must be cleaned and degreased with any solvent.
- Insert the saw’s ends into the clamp, putting it in the gap between the moving and fixed part of the construction. The joint must be straight and precise.
- To weld, set the mode of the machine. The manual adjustment is selected according to the thickness of the metal and the current pulse rate. This is to prevent the material from overheating.
- After heating, the movable clamp is shifted a little to form a welded roll.
- Welding makes the heated area stiff and brittle. Annealing helps return it to its former shape, after which the plasticity returns. You don’t have to take the blade out of the clamp to anneal. just change the current draw and get the metal to 600 degrees. expensive machines do it automatically. The cloth becomes cherry red when heated. Do not overheat to yellow and orange. Annealing is done twice with cooling for 5 minutes.
- Repeated scraping with any type of abrasive can help remove any build-up.
- Welding quality control is mandatory. It is necessary to bend the band with a circumference of 25 cm. The bend should be round. After bending, no cracks should remain in the weld. Their appearance indicates a low-quality annealing
Brazing of band saws
In the absence of a welding machine, solder the band of the saw blade. To do this, degrease it, heat the ends of the blade with a gas torch and the following operations. apply flux and melt it with the same torch, connecting by diffusion with a piece of brass:
- Let’s put a piece of brass on the end of the blade, let’s melt it in the torch flame. when melted, the steel of the saw diffuses with the brass melt at the atomic level. Use borax or special flux PV209X as flux.
- Construct a special fixture, similar to the movable and fixed clamps of a saw welding machine.
- Secure the ends and apply flux to both ends.
- Align the ends of the band in the overlay by 2 teeth.
- Put a piece of brass between the webs and heat this place with a torch.
- As the melt is forming, we join the sheets.
- Wait for complete cooling down.
- Grind the connection point until “enough is enough”.
The melting temperature of brass is about 900 degrees. The halves are heated up to this temperature. Instead of brass we can use silver solder with melting point over 900 degrees.
The overlap joint is easier, but it is harder to machine the solder joint to the proper thickness. This method is suitable only if it is impossible to use special equipment for welding.
Stages of welding work
Cutting
To begin, the saw blade must be cut to the proper length. Different tools can be used for cutting. We recommend a guillotine cutter because it gives the smoothest cut. The cut itself should be on top of the teeth. Do not forget to leave about 1-2 millimeters on the cutting side for the sludge.
To get a precise cut, you can use the technique shown in the picture below. After this cut, the saw ends will be flat and mate well. This has a direct impact on the quality of the weld.
Deburring
After cutting, the ends of the saw need to be deburred. This is the standard preparation of metal for welding. Clean all dirt and corrosion from the metal. Then degrease it with any solvent. With acetone, for example. After that, deburr the edges with an abrasive material. We use sandpaper. Make sure there are no burrs on the edges. Ideally, they should be smooth and even.
Installing the saw in the clamps
Above we could already familiarize ourselves with the components that make up a band saw welding machine. We said that there is a clamping mechanism. This is where you need to set the saw blade. The clamp has a moving part and a stationary part. Put one end of the blade in the moving end and the other end in the stationary end. There is free space between the clamps. You need to install the fabric so that its joints are exactly in the middle of this space. Naturally, the joint must be even and precise.
The choice of welding mode
Next, you need to select the welding mode. If you have a rudimentary welder, all parameters must be set manually. The welding mode is chosen based on the size of the saw and its cross section. The larger the section, the greater the welding current value. These are general recommendations.
Usually a welding machine comes with a manual, which prescribes all the modes of welding, depending on the size of the saw blade. Also pay attention to the current pulse rate setting. In budget models it should be controlled manually, otherwise the metal will be too hot. Recommended power on time is 1 to 2 seconds. On the more expensive machines, this parameter is adjusted automatically.
Welding
Band saw welding begins with turning the machine on. Depending on the model, start the band saw welding machine. This can be by a separate pushbutton or a special knob. After start-up the saw ends will be supplied with welding current which will melt the metal in the area of the future weld. The saw is energized via clamps. After the joint is heated, the movable clamp must be displaced slightly to form a welded roll. The weld is ready!
Make sure the electrode surface is clean before welding. It is not necessary to clean all of the electrodes, just the part that is in contact with the saw blade. If you ignore this rule, the connection will be of poor quality. Contaminants will impair the resistance of the circuit.
Annealing
The next step is annealing. Annealing is necessary because welding makes the metal too hard, making it more brittle. Annealing helps bring the fabric back to its original state. After spinning, the metal becomes malleable again, improving its performance.
You don’t have to take the blade out of the clamp to do the annealing. Simply switch to a different current draw. The key is to get the heat up to about 600 degrees. The more expensive machines have a separate annealing function. But if you have a simple budget model, there are a few extra steps you must take.
Above all, note that in addition to heating, you also need to cool the metal. And preferably perform these operations one after the other. Press the current button and hold it down until the heating temperature is displayed. Then release and allow the metal to cool. To evenly cool the blade, you can periodically press the button again to keep the metal from cooling quickly. On average, a cooling time of 5 minutes is required.
If your machine does not have a display for the heating temperature, the color of the metal can be used as a guide. Usually a cherry color is created when the desired heating temperature is reached. Do not allow the metal to turn orange or yellow. Sometimes it is necessary to anneal twice.
Repeated Deburring
Visible ridges may form on the sheet during annealing. They should be removed by re-scraping. Now it is not needed for technical purposes, but for aesthetic purposes. At the same time you can correct the cavities between the teeth, giving them the correct geometrical shape. Repeated deburring can be performed with any abrasive tool. Treat the metal so that the joints are almost invisible.
Band saw soldering
If there is no welding machine, solder the band of the saw blade. To do this, degrease it, heat the ends of the blade with a gas torch and perform the following operations. apply flux and melt it with the same torch, connecting by diffusion with a piece of brass:
- Let’s put a piece of brass on the end of the blade, let’s melt it in a flame of burner. while melting the steel of saw diffuses with the brass melt on the atomic level. As a flux we use borax or special flux PV209X.
- Construct a special fixture, similar to the movable and fixed clamps of the saw welding machine.
- Secure the ends and apply flux to both ends.
- Align the ends of the band in a 2-tooth overlap, aligning.
- Put a piece of brass between the strips and heat this place with a torch.
- As the melt forms, we join the blades.
- Wait for the blades to cool down completely on their own.
- Grind the joint until “that’s enough. it’s already flat”.
Brass melting point is about 900 degrees. The halves are heated to exactly this temperature. Silver brazing alloys with a melting point over 900 degrees can be used instead of brass.
Overlapped joining is easier, but it is more difficult to machine the soldering point to the correct thickness. This method is only suitable if the use of special welding equipment is impossible.
Makeshift machine for band saw welding
Often the difficulty in carrying out an independent band saw welding is the need to join blades made of different materials or have a non-standard cross-section.
In such cases, the force and amperage is set individually. In this regard, you should be prepared for the fact that the first attempt will be unsuccessful. Then, by varying the parameters, the most optimal values for a quality saw joint are selected.
To make the apparatus itself it is necessary to use the classic description for manual or semi-automatic model and on the basis of the approximate drawing assemble the construction.
When assembling the equipment and checking the wiring, think about a reliable grounding and prepare the ground site.
Let’s see a video about band saw welding with a semi-automatic:
Transformer for band saw welding with your own hands
In answering such a question, it should be noted at once that the process of self-assembly of the transformer is long and capacious. Furthermore, it is not possible to assemble an electrical design which is able to ensure the efficient and trouble-free operation of a welding machine with the required degree of safety if you are not properly trained.
Welding machine for welding strip plates
Trying to save money increases the risk, at best. of receiving a finished product of improper quality, and at worst. of burns and injuries. In this regard, it is more reasonable to make on ready-made models.
Excellent models, allowing at home to carry out band saw welding with their own hands, are the company Griggio devices modifications G 5-30, G 10-40, G 20-60, G 20-80.
The difference between these models lies in the width of the blade that is used.
Welding procedure
Regardless of the type, saw welding is carried out by the same method, step by step.
Blade preparation
To keep the ends to be joined even, the blade is cut with a guillotine. If it is not available, you can use an angle grinder or a metal chisel. When re-welding, 5 mm of the destroyed old weld is cut off at the ends. The cutting line of the trimmer must run strictly between the teeth. Allowance for the draft of 1,5 mm on both ends. Use an abrasive tool to remove irregularities and burrs. After cleaning the ends of dirt they are degreased with a solution of industrial alcohol or acetone.
Welding process
After preparation the ends of the blade are inserted into the clamping fixture of the band saw welding machine. Make sure that the edges are aligned and centered between the movable and rigid retainers. Using the enclosed table, current, force, shrinkage travel are set. Depending on the choice of operating mode, automatic or manual, the welding time is determined. In the first case, it lasts for several seconds, in the second. it is controlled by the operator.
Band saw welding process
Before welding, it is necessary to check that the electrodes are clean, because dirt creates additional resistance. After turning on the machine, a current is applied to the ends of the tape. At the place where they meet, the metal starts to melt. Simultaneous movement of the sliding clamp by the pre-set shrinkage value starts. The welding seam in the form of a bead is created as a result.
Secrets of band saw repair
Band saws are widely used throughout the woodworking industry, for joinery work, in the furniture industry, etc.д. They are used in various sawmills, band saws, and bandsaw machines.
The peculiarity of band saws is a continuous cutting surface, which is a ring of metal band with teeth. To make band saws, a pre-prepared band is welded into a ring. Welding is also used to repair torn saws. This article is about band saws welding technology.
Band saws welding technology
It is divided into several stages. preparation, sharpening, welding and flaring of the teeth of the resulting saw. At all stages it is necessary to observe due care. Let’s consider the technology in detail.
Repair of band saws, has its own peculiarities
Band saw welding machines
Typically, a band saw welder works like this: the ends of the saw are clamped in clamps, butted together, and then an electric current is passed through them, which melts and welds the edges of the ends. The current is applied through the electrodes, which are connected to the clamp clamps.
There are different types of these devices. Next, we’ll look at how they differ. Conventionally they can be classified into three groups.
Resistance welding machines
These devices are cheap, compact, not very productive and are intended for small amounts of work. for example, for saws repair in production sawmills.
Process features require high quality of seam preparation, high quality of electrodes, good adjustment of clamps and correct mode adjustment.
The melting welding machines
Performance is significantly better, these machines can be considered middle class. They operate on the principle of continuous fusion and are designed for welding all kinds of webs, including bimetals.
Process features. high demands on the surface of the blades and electrodes, need for correct spacing of teeth, taking into account metal losses. Properly selected mode is characterized by good, even melting process during the whole welding process.
Automated Fusion Welding Machines
The welding process is automated, the operator only has to install the saws into the machine and remove the welded blades. Such machines have good productivity and are usually used in service centers.
In addition to welding machines, the band saw welding process requires some auxiliary devices. guillotines for blades, stripping machines, pyrometers, and so on.
Welding process of band saws
Let’s see the welding process. As mentioned above, it is divided into several stages, which will be considered in order.
Web Preparation
Before the fabric can be welded, it must be prepared. The saw preparation consists of several steps.
Cutting of the blade
The blade is cut by means of special guillotine scissors. If these are not available, it is possible to cut the blade with a chisel or a cutting machine. If you intend to weld over an area that has been welded before, you must cut off 5 millimeters on each side of the previous weld.
The blade is cut between the tops of the teeth. Leave an allowance of about one and a half millimeters on each side. Cutting line for trimmer must pass strictly perpendicular to the back of the saw.
Band saw, a very flexible, but fragile tool
Finishing off the ends
The prepared blade must be deburred. To do this, they are cleaned of dirt, cleaned with acetone or alcohol if necessary. Edges are processed with an abrasive material, removing burrs and irregularities. this is convenient to do on a sharpening machine.
Then the band saw blade is welded. The prepared blade is fastened in the machine and welded.
Installing the saws in the machine
The prepared blade is mounted into the clamping mechanism of the bandsaw welder so that the edges of the blade coincide completely and are in the middle of the space between the clamps. Force, mode of settling and settling travel are selected according to the blade. the documentation of the machine contains tables with the information about the modes of various webs. The selected mode is set by turning the control knobs.
Welding blade
The machine is started by turning the on/off switch or pressing the button. Current begins to flow to the electrodes and melts the metal at the joint. The movable clamp goes to the stationary clamp and forms a welded bead at the place of the weld.
Important parameter. the time of current delivery. As a rule, in automatic welding it is one or two seconds, in manual welding it is controlled by the operator.
If the welding does not go well, the appropriate settings are selected and recorded; they are then used for welding similar blades in the future.
Electrodes must be clean. Poor electrode-to-blade contact increases resistance and impairs the welding process.
Saw blades require a special unit for joining
Finishing of saw blade after welding
The saw cannot be used immediately after welding. To get it in the right condition, there are several operations.
Annealing of the seam
Welding hardens the material of the blade and makes it brittle. Annealing gives it back its ductility and toughness. The saw blade is not removed from the machine; the draft is set to zero; a different current mode is selected. Press the annealing button to heat the seam and then cool it slowly. If you do not have a pyrometer, you can check the temperature visually. Optimal color of metal is cherry red. Orange or yellow color indicates overheating.
Cooling takes three to five minutes. Two cycles are necessary for some blades.
Blade cleaning
Deburring the blade from the welded area removes molten metal and corrects the shape of the cavity between the teeth of the blade. Any abrasive is good for deburring, the best is a sharpening machine.
Technological features
- Alloys from which saw blades are made are difficult to weld;
- The welding seam is under extreme strain during operation;
- The geometry of the teeth at the seam section influences the stresses at work.
From the above you have learned how band saw welding is done, what are the band saw welding machines and what are the peculiarities of this process. We hope that this information will be helpful to you.
Secrets of band saw repair
Band saws are widely used throughout the woodworking industry, for joinery work, in the furniture industry, etc.д. They are used in various sawmills, band saws and band division machines.
The peculiarity of band saws is a continuous cutting surface, which is a ring of metal band with teeth. To make band saw blades, pre-prepared band is welded into a ring. Welding is also used to repair torn saws. The welding technology of band saws will be described in the article.
Welding technology of band saws
It is divided into several steps. preparing, sharpening, welding, and setting up the teeth of the resulting saw. Due care must be taken at all stages. Let’s consider the technology in more detail.
Repair of band saws has its own peculiarities
Machines for band saw welding
As a rule, the bandsaw welder works like this: the saw’s ends are clamped in clamps, docked, and then an electric current is passed through them, which melts and welds the ends’ edges. The current is fed through the electrodes, which are connected with the clamp clamps.
There are different types of such devices. Next we will consider how they differ. They can be roughly divided into three groups.
Resistance welding machines
These machines are cheap, compact, not very productive and are designed for small amounts of work. for example, to repair saws in production sawmills.
Features of the technology requires high quality weld preparation, high quality electrodes, good adjustment of the clamps and the correct setting of the mode.
The flash fusion welding machines
Considerably higher productivity, these units can be categorized as middle class. They operate on the principle of continuous fusion and are designed for welding all kinds of webs, including bimetal.
Special features of the technology. high requirements to the surface of the blades and electrodes, the need to observe the correct tooth pitch considering the metal loss. The right mode is characterized by a good, even fusion process throughout the entire welding procedure.
Automated flash fusion welders
The welding process is automated, the operator only has to install saw blades into the unit and remove the welded blades. Such machines have good productivity and are usually used in service centers.
In addition to devices for welding, the welding of band saws requires some auxiliary devices. guillotines for blades, machines for stripping, pyrometers, and so on.
Process of band saw welding
Let’s look at the welding technique. As mentioned above, it is divided into several stages, which will be considered in order.
Preparing the blade
Before welding a blade, it must be prepared. The preparation of the saw consists of several steps.
Cutting of the blade
The blade is cut with the special guillotine shears. If these are not available, you can cut the blade with a chisel or a cutting machine. If you intend to weld over a section that has been welded before, you need to cut off 5 millimeters on each side from the previous weld.
The blade is cut between the tops of the teeth. On each side an allowance of about one and a half millimeters is left. The cutting line for the trimmer must pass strictly perpendicular to the back of the saw.
Band saw, a very flexible, but fragile tool
End cleaning
The prepared blade must be deburred. To do this, they are cleaned of dirt, cleaned with acetone or alcohol if necessary. Edges are processed with an abrasive material, removing burrs and irregularities. it is convenient to do on a sharpening machine.
Then the saw blade is welded. The prepared blade is clamped in the machine and welded.
Setting the saw into the machine
The prepared blade is mounted into the clamping mechanism of the band saw welding machine so that the edges of the blade coincide completely and are in the middle of the space between the clamps. Force, upsetting mode and course of upsetting are selected according to the blade. the documentation of the machine contains tables with information about the modes of various blades. The chosen mode is set by turning the control knobs.
Welding the blade
The machine is started by turning the on/off switch or pressing a button. The current starts to flow on the electrodes and melts the metal at the joint. The movable clamp goes to the stationary clamp and forms a welded roll in place of the weld.
Current time is important. As a rule, in automatic welding it is one or two seconds, in manual welding it is controlled by the operator.
If the welding is not satisfactory. suitable settings are selected and stored; they will be used for welding of similar saw blades in the future.
The electrodes must be clean. Poor contact between the electrodes and the blade increases resistance and impairs the welding process.
Saw is required for joining
Handling the saw after welding
Immediately after welding the saw is not usable. Several operations are performed to bring it to its proper condition.
Annealing of the seam
Welding makes the fabric material harden and become brittle. Annealing allows it to regain ductility and toughness. Saw is not removed from the machine, draft is set to zero, other current mode is selected. Press the annealing button to heat up the seam and then cool it down slowly. If there is no pyrometer, the temperature can be checked visually. Optimal color of metal is cherry red. Orange or yellow color signals overheating.
Cooling takes three to five minutes. Two cycles are necessary for some webs.
Cleaning of blade
When deburring the blade, the weld metal is removed from the welded area and the correct shape of the cavity between the teeth of the blade is created. Any abrasive is suitable for deburring, the best is a sharpening machine.
Process Features
- The alloys from which saw blades are made are difficult to weld;
- The welding seam is under extreme strain during operation;
- Teeth geometry in the seam section influences the working loads.
From the above you have learned how band saw welding is done, what are the machines for band saw welding and what are the peculiarities of this process. We hope that you will find the above information useful.
Soldering
When the contact method of welding is not available, use high-temperature soldering with silver solder with a special paste flux based on borax. To fix the ends of the blade used a simple homemade device. Heating is accomplished with a gas torch.
Brazing is performed according to standard procedures. Flux is applied to the beveled ends of the saw. After clamping in the fixture, the junction is heated to the melting point of the solder placed next to it. It will be pulled into the joint by capillary forces. After the entire joint line is exposed to solder, the heating stops. After cooling down, the saw is taken out and cleaned of the buildup.