And its analogues are one of the most common types of metal-cutting equipment in the post-Soviet space. It began to be produced almost fifty years ago (in 1971) and is still used in various industries: from small workshops to large ones industrial enterprises. 16K20 has many modifications and analogues, which are produced not only in the former Soviet republics, but also at several machine tool factories in China and Bulgaria.
The repair of these lathes is well mastered at many enterprises, since over many years the layout and composition of the mechanisms of the 16K20 have remained virtually unchanged. The order and composition of repair work also remained unchanged, although now this equipment is repaired not only traditional methods, but also with the use modern technologies and materials.
Possible faults
During long-term operation of turning equipment, the parts of its mechanisms lose their original qualities, which leads to a change in their shape, an increase in gaps at the interfaces and a deterioration in the condition of the friction surfaces. One of the main reasons for the occurrence of such malfunctions is wear of the friction surfaces of individual parts, which occurs as a result of:
- influence of friction force;
- plastic deformation (metal collapse);
- surface layer fatigue;
- chemical corrosion.
Possible malfunctions of the main elements of the lathe:
- Case parts. Cracks, chips, wear of holes, damage to threads, deviation from straightness of planes.
- Shafts. Wear of journals, keyways, center holes.
- Flanges. Cracks and chips in mounting holes. Wear of mating surfaces.
- Gears and pinion shafts. Tooth wear and radial runout of the ring gear.
- Spindle. Worn journals, front inner cone and spline joint.
- Lead screw. Wear of threads and journals.
- Running roller. Wear of the keyway and journals.
Based on the inspection and control measurements of these 16K20 components, the need for repair is determined and preparations for repair and restoration work are carried out. Inspecting the machine for repairs begins with the pulley, which on a 16K20 lathe transmits motion from the main motor to the spindle. A list of the main problems that arise as a result of violations of the equipment operation rules is given in section 16 of the “Operation Manual.” Possible causes and methods for eliminating them are also indicated here.
Types of repairs
Repair work is carried out in order to maintain the operational characteristics of turning equipment and is of two types: planned and unscheduled. The first ones are carried out only on the basis of preventive maintenance schedules. For 16K25, four types of work are provided, including inspection and three types of repairs:
- small;
- average;
- capital.
According to clause 17.2 of the “Operating Manual” of the 16K20 lathe, its turnaround period (working time before the first overhaul), subject to compliance with the manufacturer’s operational requirements, is 10 years with two-shift operation. During this period, six scheduled inspections 16K20, four minor repairs, one medium (in the middle of the period) and one major (at the end of the period) must be performed.
The need for unscheduled repair work usually arises when the permissible parameters of equipment suddenly decrease or fail. This usually happens when the manufacturer’s specifications for the operation and maintenance of turning equipment are not met. On manufacturing enterprises All types of work are carried out according to maintenance schedules by qualified personnel of specialized repair departments. In small enterprises, repairs to a lathe are carried out with their own hands as problems arise with its accuracy and performance.
This type of repair work is carried out both according to the approved nomenclature and according to the results of observations of turning equipment during shift and periodic Maintenance. Its purpose is to ensure the operation of turning equipment until the next scheduled repair.
According to clause 17.3.3 of the “Operation Manual” for the 16K20 lathe, minor repairs are required to be carried out the following types works:
- identifying faults for elimination during subsequent scheduled repairs;
- measurements of equipment geometry for certified accuracy;
- idle tests;
- noise and temperature tests;
- checking the accuracy and purity of processing.
The rest of the work from the list given in the Manual is carried out only if necessary, depending on the condition of the equipment. Based on the results of minor repairs, a statement of the condition of machine parts is compiled for inclusion in the following PPR schedule works
Medium renovation
This type of repair work includes work according to the list of recommendations for minor repairs, as well as partial disassembly of the turning 16K20, during which the functionality of the main mechanisms and assemblies is restored. Such repairs for the 16K20 screw-cutting lathe are carried out according to the list given in paragraph 17.3.4 of the “Operating Manual”.
During an average repair, the accuracy is checked before and after disassembling the turning equipment, the spindle rigidity is checked, and the wear of the friction surfaces is measured before and after their restoration. The average repair of a lathe is performed in the middle of the overhaul period. Its goal is to restore the service life of turning equipment to such a level that the machine can operate until overhaul.
Major renovation
According to clause 17.3.2. In the “Operating Manual”, a major overhaul of the 16K20 lathe is preceded by an inspection of the condition of the machine equipment. During the inspection, inspection data from previous repair work is checked, lists of parts for restoration and replacement are determined, and working drawings are produced for ordering replacement parts.
During major repairs, before complete disassembly, the accuracy of 16K20 and the degree of wear of the friction surfaces will be checked.
After complete dismantling of all mechanisms, each part is cleaned, after which they are inspected and compared with the defective list. The overhaul involves the restoration of all passport characteristics of 16K20. Therefore, lathes after a high-quality overhaul have the same parameters as new turning equipment, and their overhaul period is also ten years.
Download the passport (operating instructions) of the lathe 16K20
Repair of main components
bed
The 16K20 bed is a cast structure with stiffening ribs on which all other equipment of the lathe is mounted. On the top of the bed there are four longitudinal guides of the lathe: two flat and two prismatic. The positioning accuracy of the tailstock and caliper carriage, as well as the alignment of the front and rear stock, depends on the condition of their surfaces. The composition and procedure for performing the work is regulated by section 6.1 of the technical manual “Repair of a 16K20 screw-cutting lathe.”
There are four machining methods used to repair lathe guides:
- manual scraping;
- grinding using portable grinding equipment;
- grinding on surface grinding equipment;
- planing on a longitudinal planing machine;
In general, if the wear is less than 15 microns per 1000 mm, the surface geometry is restored by manual scraping. If more - with the use of machine equipment or the spraying method.
Scraping is performed using hand tools, so its labor intensity is several times higher than with mechanized processing.
In addition, only non-hardened surfaces can be treated with this method. It is possible to scrape the bed of a lathe without dismantling the bed, therefore, along with manual grinding, this is the most common method of restoring guide surfaces.
Grinding of guides using portable grinding equipment installed on the bed is used in two cases: if it is impossible to deliver the bed to the repair shop and if the length of the bed is greater than the length of the grinding equipment table. Most effective method restoration of the bed guides is processing on grinding and longitudinal planing machines in repair shops or at specialized enterprises. It provides the highest precision and guarantees quality.
Restoration of deep damage to the lathe bed is carried out by spraying brass or zinc, as well as filling it with babbitt. After filling the dents and potholes with metal, the surface of the guide is processed by grinding or scraping.
Carriage
In accordance with section 6.2 of the Technical Manual, repairing the slide carriage of a 16K20 screw-cutting lathe includes two technological operations:
- restoration of the lower guides associated with the bed guides;
- restoration of the transverse guides adjacent to the guides of the lower part of the caliper.
Before starting work, the carriage is installed on the exposed bed along with the rack and feed box. After this, clamping bars, an apron, a lead screw and a running shaft are mounted on the carriage, it is set for accuracy, measurements are taken and the engagement of the apron gear with the rack is checked.
Based on the results of control measurements, the degree of wear of the guide surfaces is determined and they are processed manually and mechanically until the standard straightness, flatness and parallelism are achieved. At the final stage, the accuracy of fit to the lathe bed is ensured by processing with a scraper and grinding devices.
According to section 6.7 of the Manual, the range of repair work 16K20 includes technological operations to restore the parameters of the following components:
- surfaces of the body mating with the surfaces of the plate;
- surfaces of the plate adjacent to the body and frame;
- hole for quill.
When restoring flat surfaces, scraping and grinding are used, and when processing quills, boring is used.
Grinding of flat surfaces of guides is carried out on a longitudinal grinding machine. Prismatic surfaces are brought to standard quality by scraping. Boring the hole for the quill is done in two ways: on the machine itself using a boring bar and with dismantling on a boring machine.
|
Remedy |
||
|
Ovality of the part. The internal diameter of the hole is not maintained |
Workpiece runout in the chuck. Transverse displacement of the tailstock (during drilling). Poor tailstock fastening. Incorrect drill sharpening |
Adjust the workpiece in the chuck for runout. Boring the cams. Adjust the tailstock along the spindle axis. Secure the tailstock. Resharpen the drill |
|
The axis of the part hole is shifted |
Insufficient centering depth. The tailstock quill axis does not coincide with the spindle axis. Incorrect drill sharpening |
Center the workpiece, following all the rules. Adjust the tailstock along the spindle axis. Resharpen the drill |
|
Taper of machined part |
Offset of spindle and tailstock centers |
Adjust the alignment of the centers of the headstock and tailstock |
|
The presence of a spiral (helical) mark on the part during the reverse stroke of the cutter. Unclean end of the part from the cutting side |
Incorrect cutter installation. Incorrect sharpening of the cutting edges of the cutting tool (the right auxiliary surface has a small auxiliary lead angle and a small relief angle) |
Set the cutter slightly above the center. Resharpen the cutter |
|
When cutting the end, the size along the length of the part is not maintained |
The workpiece is loosely secured. Incorrectly determined location for processing the end of the workpiece |
Firmly secure the workpiece in the chuck. Follow all trimming rules |
|
Crushed surface treated |
Gaps in caliper guides. Weak fastening of incisors. Weak fixation of the workpiece in the chuck (centers). The workpiece vibrates during processing. Long cutter overhang. The cutter is not centered |
Tighten the caliper bars and wedges. Fasten the cutter firmly. Reduce cutter overhang. Set the cutter exactly along the center axis. Firmly secure the workpiece |
|
Remedy |
||
|
Torn threads on a rod or hole |
Very soft and viscous workpiece material. The workpiece diameter does not meet the requirements. High cutting speed |
Reduce the diameter of the threaded rod or increase the diameter of the threaded hole. If possible, replace the workpiece. Reduce spindle speed |
Close the spindle with a casing and lower the protective screen;
Turn on the main drive electric motor by pressing the “start” button.
While performing work you must:
Turn on the main drive drive using the main drive friction clutch control handle;
Bring the cutter to the workpiece to be processed until it touches, using manual longitudinal and transverse feeds, using the appropriate flywheels;
Set the transverse and longitudinal feed dials to zero. Before setting the dials to zero, be sure to select the backlashes (air gaps) in the feed mechanisms;
Remove the cutter from the processing area;
Set the required cutting depth using the dials;
Turn on the automatic longitudinal or transverse feed mechanism;
Process the workpiece at a given length (at the end). At the end of turning, turn off the automatic feed;
Move the cutter away from the workpiece and return it to the starting point at rapid feed or manually;
Continue processing in the same sequence until the workpiece has the appropriate dimensions;
When cutting, monitor the flow of chips and, if necessary, remove them; in this case, the cutting process must be interrupted. Removal of chips should only be done with a special hook.
Upon completion of the work you must:
Turn off the electric motor with the “stop” button;
Turn off the input automatic switch;
Remove the processed part, processing tool and additional equipment from the machine;
Set the tailstock to the extreme right position;
Move the machine support to the right towards the tailstock;
Clean the machine from chips and dirt using a hook, scraper, brush and rags;
Lubricate the machine at lubrication points and rubbing surfaces.
Defects during broaching and ways to prevent them
Most lathes have a similar structure: a workstock, spindles and a bed. On lathes, parts are processed mainly in the horizontal plane. Screw-cutting machines differ from standard lathes in the presence of a front and rear working headstock, an elongated bed and support, as well as a feed box.
A special feature of the repair of screw cutting machines is the work with cutters, drills and other equipment for internal processing of parts.
The main causes of breakdowns of screw-cutting lathes
- As practice shows, the spindle speed control unit is often the first to fail. It is the tapered roller bearings used in such machines that are subject to the maximum degree of wear. Depending on the type of machine and the type of circular lubrication system, periodic adjustment or replacement of bearings is required.
- In addition, malfunctions often occur in the fixing caliper holder. As a result, the workpiece being processed moves unevenly in the longitudinal and transverse directions.
Different models of screw cutting machines differ in the types of workpieces, sizes and design. For example, there are automatic and semi-automatic machines. They differ in the presence of special sensors for feeding the working heads. In practice it is automatic systems work longer, since during manual feeding the size of the part and the degree of its processing may be incorrectly calculated.
Repair of screw-cutting lathes
A machine of this type is classified exclusively as complex equipment. Moreover, if the equipment is additionally equipped with heads for milling or grinding. Therefore, it is recommended that machine repairs be carried out by specialized companies.
Of course, our own staff of engineers can carry out routine repairs, consisting of lubrication of working parts and control inspection of the condition of working elements. But complete overhauls are best done by a professional.
Specialists in the repair of screw-cutting lathes carry out their work in accordance with uniform norms and work standards, taking into account the specific features of your model. In addition, such repairs will always be carried out with a guarantee for spare parts and the work itself.
Therefore, in order to save money and reduce downtime, which means additional losses, you should not resort to repairing screw-cutting lathes yourself. After all, imaginary savings can lead to unimaginable waste.
During the operation of the lathe, sooner or later you will encounter some kind of malfunction. The likelihood of a breakdown is especially high if you are using a unit with considerable mileage. In this case, you need to be prepared not only for minor malfunctions, but also for the possible need to overhaul the lathe, and this is a very, very expensive undertaking.
Fortunately, the design of most units (especially those produced during the Soviet era) is simple enough for you to cope with the repair of a lathe without the involvement of a third-party specialist. Below, using the 1K62 model as an example, we will look at the most common breakdowns, the causes of their occurrence and methods of elimination. If in practice you encounter the problems described, you will most likely be able to carry out repairs on your own, following the recommendations below.
Main breakdowns, causes and methods for their elimination
The initial cause of most malfunctions in the operation of a lathe is improper operation and care of the equipment. The technician should know how to service the unit. This will allow you to save considerable amounts in the future, since major repairs of lathes are expensive, even if you do the repairs yourself.
Experts recommend that before starting to work with the machine for the first time, you study in detail the operating instructions and other documentation that comes with the equipment. If you purchase a used machine without instructions, then it makes sense to find all the documentation related to the 1K62 unit or any other model yourself on the Internet.
Now that you have learned about the intricacies of operating your “assistant,” it’s time to study the most common breakdowns and how to fix them. For ease of understanding, we present tips for repairing a 1K62 lathe in the form of a list:
- The machine does not turn on. The most common and easiest problem to solve. It is most likely due to a lack of mains voltage. The technician is recommended to check the presence and voltage indicators.
- It is not possible to shift the gear unit using the handle; the unit makes a typical slipping sound. This kind of problem is due to the fact that the block does not move out of the idle position. It is recommended to restart the electric motor and engage the gear “on the freewheel”.
- The electric motor switches off spontaneously during operation. Most likely, this triggers a relay that protects the power unit from excessive load. In this case, the master should reduce the intensity of cutting or feeding.
- Insufficient spindle torque, which does not reach the limit specified in the documentation. The problem may be that the belt tension is not tight enough. By increasing it, you will increase torque. Another cause of the problem may be a poorly tightened friction clutch, by increasing the tension of which you will also be able to increase torque.
- Slow spindle braking. In most cases, the cause of this malfunction is insufficient tension in the brake band. By increasing this parameter, you will notice that braking has become more dynamic.
- The caliper feed gain does not reach the values specified in the documentation. To cope with the problem, experts recommend tightening the spring of the overload device more strongly.
- The cooling pump is not functioning. Typically, this problem is associated with an insufficient level of coolant in the system. By topping it up, in most cases you will be able to eliminate the problem. Failure of fuses may also be the cause of this problem. A simple replacement with new ones will solve the problem that suddenly arises in front of you.
- Excessive vibration of the machine during operation. There may be several reasons for this. The first is incorrect level installation of the unit. In this case, you need to align the machine. Second possible reason– this is wear at the joint of the caliper guides. Tighten the clamping wedges and strips, and, most likely, the situation will improve. Also, excessive vibrations are often associated with incorrect selection of the cutting mode or improper sharpening of the cutting tool.
- The processing accuracy of the workpiece is unsatisfactory. There are four main reasons for this problem. This is a transverse displacement of the tailstock, excessive overhang of the structure fixed in the chuck, and insufficiently rigid fixation of the cutter holder or chuck. In the first case, you need to adjust the position of the headstock, in the second, press the structure with the center or support it with a rest. In the third and fourth cases, you should tighten the cutter holder handle or chuck mounting straps.
Often the 1K62 lathe needs to be repaired due to a malfunction of the lubrication system. If there is no weak stream of lubricant in the oil indicator, this indicates that the pump lever stop screw is not adjusted. The technician needs to adjust the position of the plunger.
If there is a stream of oil, but it is very weak, then most likely the reason is a dirty filter. The problem can be solved by simply washing the filter.
In addition, a malfunction of the plunger pump spring can lead to a complete lack of lubricant flow into the oil indicator. Replacing the spring will fix the problem. If the lubricant is not supplied to the frame guides, then the reason most likely lies in contamination of one of the valves of the plunger pump. Again, repairs involve a thorough cleaning.
Results
As you can see, you can repair lathes yourself if you understand how to eliminate basic faults. We hope that the information presented will save you money and a lot of time.
Any equipment sooner or later fails, so repairing a lathe is simply necessary, since purchasing a new machine can cost a lot of money, and, frankly, there is no point in it.
First, let's look at what turning is, the structure of the machine, and also talk about the overhaul of the tailstock of a lathe.
The technological process of turning consists of reducing the diameter of the workpiece using a cutter, which is equipped with a special cutting edge.
Due to the rotation of the workpiece, the cutting process occurs; feed and lateral movement are carried out by the cutter.
Thanks to these three components: rotation, feed, movement, it is possible to influence the amount of material removal; the quality of the machined surface, the shape of the chips, etc. also depend on this.
Basic elements of a lathe:
- Bed with guides for the tailstock and support;
- At the front of the bed is the headstock, as well as the spindle and chuck;
- A gearbox is attached to the front part of the frame;
- Support with slide for cross-cutting;
- The cutter holder is located on the cross slide.
These elements are the main ones; depending on the modifications, you can get centering, turret lathe, multi-cutting and other machines that must undergo mandatory maintenance.
Preparation for repair
The most common problems include wear of bearings, guides, gear forks, etc.
Major repairs can only be done after preparing the equipment.
Before stopping the machine, it is necessary to check how it operates idle to determine the increased level of vibrations and noise.
To determine the rolling condition of the spindle supports, a sample must be processed. The axial and radial runout of the spindle is also checked.
These actions will allow you to correctly identify problems that have arisen, since they are not always obvious.
In general, the enterprise must maintain machine tools according to a calendar schedule.
Thus, it is possible to eliminate breakdowns and shortcomings in a timely manner to avoid major repairs.
If you send the machine for major repairs, you must first wash it from dirt and dust.
You also need to drain the oils and emulsions and check that all parts are in place.
For cleaning and lubricating the guides, see the video.
Guide repair
Overhaul of the bed guides can be performed in several ways: scraping, grinding, planing.
To determine the amount of wear on the guides with your own hands, you need to clean the surface and remove nicks.
After this, the gap between the guides is measured using a ruler along the entire length of the machine. Measurements are taken in increments of 30-50 cm.
The straightness of the guides can be checked using very thin paper (no more than 0.02 mm), tissue paper is suitable for such purposes.
The sheets must be laid out on the guides and pressed down with a light object.
With normal straightness, it will not be possible to pull out the leaves whole from under the object, only in fragments.
Scraping is carried out after installing the equipment on a coating characterized by its rigidity (special stand).
You can also determine deviations by the level that moves along the guides or along the tailstock bridge.
The guides located at the bottom of the tailstock are usually chosen as a reference surface as they are subject to less wear.
Before sanding, it is necessary to clean the surfaces to remove all nicks.
To perform this work, it is necessary to use a planer table on which the bed will be installed.
After this, it must be checked for parallelism.
The bed must be securely fastened to the table; the final result will depend on this. The curvature of the guides is measured again (the indicators before and after installation should not differ) and grinding begins.
Repair of guides by planing begins with cleaning the surface, installing a longitudinal planing machine on the table, after which it is checked for parallelism and fixed.
For best results, surface treatment with a cutter is carried out 3-4 times.
After completing the work, it is necessary to check the straightness, parallelism and crookedness of the guides and unfasten the equipment.
Features of guide processing
It should be taken into account that the scraping process involves the use of a certain order of work, which may differ for different machines.
Let us consider below the technology for performing scraping on a screw-cutting lathe:
- First, the guides, which are located at the bottom of the tailstock, are processed;
- Next - located under the clamping bars and at the bottom of the carriage, while deviations in parallelism should not be allowed to exceed 15 microns;
- Then – scraping of the transverse caliper. Minor errors are allowed;
- The next stage of repairing a screw-cutting lathe is scraping the carriage (counter guides). A triangular ruler is used to determine the error. The difference between the screw axis and the guides should not be more than 35 microns;
- If the longitudinal guides of a screw-cutting lathe are heavily worn, it is necessary to use an anti-friction compound. The important point here is to achieve compliance along the axes of the running shaft with the landing zone; the travel rack must have good adhesion to the gear in the longitudinal direction; in the transverse direction, the spindle axis must be perpendicular to the movement of the caliper;
- Next, the tailstock guides are repaired using an antifriction compound.
See video about rough scraping.
It is better to trust the maintenance of machines to specialists, since the work must be performed accurately, professionally, without deviations.
It will be difficult to achieve such results with your own hands.
Repairing the caliper carriage
Restoring the accuracy of the lower guides, which are associated with the base guides, without taking into account wear - this is where you need to start repairing the caliper carriage.
Also, when repairing the carriage, it is necessary to restore the perpendicularity of its plane under the apron of the base plane (under the gearbox).
The location of these planes is measured by a level. The thickness of the probe placed under the carriage will determine the level of deviation (value).
The parallelism of the longitudinal guides and their parallelism to the axis of the transverse feed are also subject to restoration.
The longitudinal and transverse guides must be exactly aligned with each other.
It should be noted that repairing a caliper carriage is a very labor-intensive process; it is very difficult to do it yourself, so the company must schedule maintenance of the device on a schedule.
The carriage guides can be restored using compensation pads or acrylic plastic.
The cross slide of a screw-cutting lathe can be repaired by grinding. The rotary sled begins by scraping the surfaces, after which they begin sanding.
If necessary, the upper skids are also repaired.
To do this, the surface is scraped, aligned, polished, after which the accuracy of the surfaces’ mating with the guides of the rotary slide must be checked.
See the video for scraping the cross carriage.
Lead screw and lead shaft
During a major overhaul, it may be necessary to align the axes of the lead screw and shaft, feed box and apron.
The feed box is installed and secured to the base.
The carriage must be moved towards the feed box until the ends of the frame touch. Next, you need to measure the clearance using a feeler gauge with a ruler.
Using pads and scraping the guides, you can restore the alignment of the holes of the lead screw and the shaft.
Loading...