JPH0453623A - Grinding method and device for dual lead worn in numerically controlled grinding machine - Google Patents

Abstract

PURPOSE:To have a dual lead worm subjected to automatic thread grinding in a short time by putting a grinding wheel narrower than the ground groove of a thread ridge, in an interval between both lead surface, or on one side and on the other, and machining both these lead surfaces by means of automatic thread grinding in accordance with each lead while reciprocating the grindstone as many times as the shift number. CONSTITUTION:A grinding wheel 12 is formed so that it is narrower than the minimum width size (a) of every part of the grinding groove, and set to a form with the same incline as each of lead surfaces 3, 4, and each of technical data such as lead L1 of a lead surface 3 on one side of a thread ridge 2, lead L2 of a lead surface 4 on the other, an initial position and a stroke of a table 10 at time of grind starting, offset value between these lead surfaces 3 and 4, feed traveling rotation of the grinding wheel 12 ranging from grind starting to its termination, feed per stroke at each time of the grinding wheel 12 and so on are all inputted into a numerical control system 21 as a command value, and this N/C system 21 controls two motors 11, 20 and the feed-per-stroke of the grinding wheel 12 in synchronization, while controlling the table 10 for positioning to perform thread grinding for both these lead surfaces 3, 4 while shifting the grinding wheel 12 as much as the offset value corresponding to the feed in rate.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is directed to a multi-lead worm in an NC grinding machine that automatically thread-grinds different worms of leads on one and the other lead surface of a screw thread using an NC machine. Concerning grinding methods and equipment.

[Prior Art] Multi-lead worms are often used for the purpose of eliminating backlash or as a feed screw mechanism that requires slight changes in the feed speed in both reciprocating processes, such as the feed screw in an injection device. . As shown in FIG. 2, the multi-lead worm 1 has a lead (L,) on one lead surface 3 of one screw thread and a lead (L2) on the other lead surface 4.
) are different from each other. That is, as shown in Fig. 3, the pitch circumference length (πD) of the thread 2 is plotted on the horizontal axis.
If we take the lead L on the vertical axis, the lead surfaces β0. of the lead surfaces 3 and 4. β2 is different as shown.

When grinding a thread with a constant lead that is not a double lead, a grindstone with a thread shape that matches the shape of the thread is brought into contact with the lead surface of the thread at the same time, and the grinding process is performed several times depending on the grinding allowance. It is normal to grind both lead surfaces according to a predetermined lead while making a cut, and then finish the grinding. In the NC grinding machine as well, the first motor that rotates the worm and the second motor that reciprocates the table are synchronously controlled in correspondence with the predetermined lead to perform grinding. In addition, in a thread grinding machine other than an NC grinder, a gear mechanism is provided between a drive source, a main shaft, and a table, and the gear mechanism is assembled in correspondence with the lead, and the main shaft and table are driven synchronously to screw the thread. Grinding is usually performed.

[Problems to be Solved by the Invention] In order to thread-grind a multi-lead worm using an ordinary thread grinding machine having the gear mechanism, first, the gear mechanism is turned to thread-grind the negative lead surface with a predetermined lead. After assembling and thread-grinding by a predetermined grinding allowance, the gear mechanism is rearranged to thread-grind the other lead surface with a predetermined lead different from the above, thread-grinding is carried out by a predetermined grinding allowance, and then one lead surface is ground again. The only way to complete thread grinding was to alternately repeat grinding one lead surface and then grinding the other lead surface. In other words, it is necessary to reassemble the gear mechanism each time changing from one lead surface to the other, and if the grinding allowance is large, the number of repetitions is large, requiring an extremely long grinding time. For example, it may take eight hours to thread-grind a multi-lead worm. Furthermore, in order to perform high-precision thread grinding, it is necessary to perform high-precision alignment between the grinding wheel and the threads of the workpiece, and when using the gear mechanism described above, alignment must be performed each time. There are problems in that it takes a long time to set up the alignment and requires a high level of skill.

The present invention aims to provide a method and apparatus for grinding a multi-lead worm in an NC grinding machine, which can automatically thread-grind a multi-lead worm in a short time, improve work efficiency, and enable high-precision thread grinding. purpose.

[Means for Solving the Problems] In order to achieve one or more objects, the present invention provides a method for grinding a multi-lead worm in which the lead on one lead surface of the screw thread is different from the lead on the other lead surface. , In an NC device attached to the grinding machine, each lead, the initial position of the table at the start of grinding, the table stroke, and the amount of movement (offset amount) of the grindstone between the one lead surface and the other lead surface.

Input each specification such as the number of feed movements (shift number) of the grinding wheel from the start of grinding to the end of grinding, and create a groove with a width smaller than the grinding groove of the thread between the one lead surface and the other lead surface. A method for grinding a multi-lead worm in an NC grinding machine is characterized in that a grindstone is inserted and the grindstone is reciprocated by the number of shifts while automatically thread-grinding both lead surfaces according to the respective leads, and further comprising: a first motor that rotates a small-width grindstone and a multi-lead worm;
a second motor that reciprocates the table; an NC device that is connected to the two motors and controls their operation in correspondence with the leads; the NC device is connected to each of the leads; the initial position of the table at the start of grinding; It is composed of a specification input means for inputting specification values such as the table stroke (offset amount), the number of movement of the grindstone from the start of grinding to the end of grinding (number of shifts), and While sequentially engaging the lead surface of the grinding wheel and the other lead surface, the grinding wheel is
Controlling the first and second motors.

The means for this purpose is a multi-lead worm grinding device in an NC grinding machine configured to thread-grind both lead surfaces into predetermined leads.

[Operation] Each specification necessary for thread grinding of a multi-lead worm is input into the NC device in advance by the specification input means.

First, one lead surface is ground using a grindstone with a width smaller than the minimum grinding groove width of the multi-lead worm.

That is, the table is positioned at a predetermined initial position by a command from the NC device, and one lead surface is ground by a predetermined grinding displacement by a command to start grinding. Next, the grindstone is automatically moved by a predetermined offset amount, and thread grinding of the other lead surface is performed.

Next, the grindstone returns to the one lead surface side again, and thread-grinds the one lead surface according to a predetermined grinding allowance.

Next, the grindstone is moved to the other lead surface side again.

Thread grinding of the other lead surface is performed. The grindstone sequentially reciprocates by the number of shifts input in advance to complete thread grinding on one and the other lead surface.

The feed amount, offset amount (reciprocating amount), lead, etc. of the grinding wheel are all controlled by commands from the NC device.

Multi-lead grinding will be performed automatically. Therefore, there is no need to stop the machine and change the setup every time the lead surface changes, and the thread grinding time can be significantly shortened.

[Example] Hereinafter, a preferred embodiment of the present invention will be described based on the drawings.

Lead L1 as shown in FIG. A multi-lead worm 1 having an L2 thread 2 is supported between a main spindle center 5 and a tailstock center 6, as shown in FIG. Ru.

Further, a headstock 8 that pivotally supports the main spindle 7 and a tailstock 9 that supports the tailstock center 6 are placed on the table 10. Further, a first motor 11 for rotationally driving the main spindle 7 is arranged on the headstock 8 . On the other hand, the whetstone 12 is supported by a whetstone head of the circuit so as to be able to reciprocate in a direction perpendicular to the plane of the paper.

The table 10 is slidably supported on a bed 15, and a feed nut 13 fixed to the table 10 has a feed screw 1.
4 are screwed together. The feed screw 14 is supported at both ends by brackets 16 and 17 fixed to the bed 15 side, and is supported by a gear mechanism 18 . It is connected via a speed reducer 19 to a second motor 20 for feeding the table 10 .

First motor 11. The second motor 20 and the grindstone 12 are connected to an NC device 21, and the NC device 21 is configured to perform NC control on them. NC device! 21 is connected to an MDI 22 which is one of specification input means.

The grindstone 12 for grinding the thread 2 of the multi-lead worm l has a width smaller than the minimum width dimension a of each part of the grinding groove as shown in FIG. (already shown), and is formed from a material having the same sloped surface as the lead surface 3.4.

The following command values are input to the NC device [21] by the MDI 22. Namely.

The lead L□ on one lead surface 3 of the thread 2 and the lead L3 on the other lead surface 4. The initial position of the table 10 at the start of grinding corresponding to the start position of the grindstone 12, the stroke of the table 10, the amount of offset between the lead surfaces 3 and 4 (a value that changes depending on the grinding allowance), from the start of grinding to the end of grinding. Each specification, such as the number of feed movements of the grindstone 12, ie, the number of shifts, and the amount of feed of the grindstone 12 each time, is recorded as a command value in the NC system! 21. The NC unit M21 performs necessary calculations based on the above command input values, and controls the first motor 11. The table 10 is used to synchronously control the feed rate of the second motor 20 and the grindstone 12, and to alternately thread-grind the lead surfaces 3 and 4 while moving the grindstone 12 by an offset amount corresponding to the cutting depth. is configured to control positioning.

Next, the operation of this embodiment will be explained in more detail.

As shown in FIG. 4(a), a small-medium grindstone 12 is selected based on the minimum grinding groove width dimension of the thread 2.

The grinding allowance for thread 2 is assumed to be 61. Also, for the sake of explanation,
The number of shifts shall be two. In other words, it is assumed that thread grinding is completed with two cuts, but in reality, it is
The number of shifts as shown in the figure is required.

First, the grindstone 12 is brought into contact with one lead surface 3 as shown in FIG. 4(a). Next, as shown in FIG. 4(b), the grinding wheel 12
Make a cut and perform thread grinding until the grinding allowance becomes 62mm.

In thread grinding, first, the grindstone 12 in the initial position is moved to the thread 2 of the multi-lead worm 1 by the movement of the table 1o.
is moved to the position , and thread grinding is performed by the lead L1 of the lead surface 3. In this case, the first and second motors 11.20 are synchronously controlled by the NC device 20 so that the lead L□.

Next, as shown in FIG. 4(c), the grinding wheel 12 is moved by an offset c1 according to a command from the NC unit N20, and brought into contact with the other lead surface 4 side, and the lead surface 4 is moved as shown in FIG. 4(d). ) Screw grinding is performed to a position where a grinding allowance δ2 is left. Next, as shown in FIG. 4(e), the grindstone 12 is moved by an offset amount c2, and as shown in FIG. As shown in FIG. 4(g), the grindstone 12 is moved to the lead surface 4 side by an offset amount C1, and the lead surface 4 is thread-ground into the final shape.

The engagement relationship between the grindstone 12 and the multi-lead worm 1 from FIG. 4(a) to FIG. 4(g) is all automatically controlled by the NC device 21 based on the command value input by the MDI 22. Therefore, no manual adjustment work is required during grinding.

FIG. 5 shows the above operation in a flowchart.

First, a grindstone 12 with small and medium dimensions and a predetermined pressure surface is set.

Next, the workpiece, the multi-lead worm 1, is held between the spindle center 5 and the tailstock center 6 and centered. MDI
22, lead L engineering, L2. Various specifications such as the initial position of the table 10, the stroke of the table 10, the offset C1, the number of shifts, and the amount of feed of the grindstone are input to the NC device 21. When the grinding starts, the table 10 is positioned at the initial position.

As the table 10 moves, the grindstone 12 approaches the multi-lead worm 1 side. Then, the first of lead L1 on lead surface 3
Thread grinding is performed twice, the table 10 is positioned by a predetermined stroke, and then returns to the original initial position. Next, the table 10 is moved by the offset C1, and the first thread grinding by the lead 2 on the lead surface 4 is performed. The table 10 is moved again by the offset C2, and the second thread grinding of the lead L□ of the lead surface 3 is performed, and the thread grinding of the lead surface 3 is completed. Next, offset C1 table 10
moves to lead surface 4 again, and leads L2 of lead surface 4
A second thread grinding process is performed, and the thread grinding of the lead surface 4 is completed. The table 10 returns to its original initial position,
Thread grinding is completed.

As described above, in this embodiment, the grinding was completed after two shifts, but of course, the same applies to the case where the number of shifts is several or tens of times. In addition, if the width of the cutting groove is relatively wide, a grinding process may be laid out in which only the troughs are first ground before the lead surfaces 3 and 4 are ground, and then the threads are ground alternately as described above. Of course I don't mind.

[Effect of the invention] According to the present invention, the following effects can be achieved.

1) By inputting the necessary specifications into the NC device in advance,
Alternate thread grinding of lead surfaces is completed.

Therefore, unlike the prior art, there is no need to change the setup of the gear mechanism each time, and the working time can be greatly shortened and the working efficiency can be improved.

2) Automatic grinding using an NC device does not require special skill, and as long as there are no errors in the input values, a multi-lead worm of the desired shape can be easily ground and finished with high precision.

3) Since the relative position between the table and the grindstone is automatically controlled by the NC device, it is not necessary to align the workpiece each time, and highly accurate thread grinding is performed.

4) Because it is input using MDI etc., even if the numerical values of various specifications of leads etc. change, it can be easily handled.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view showing the thread shape of a multi-lead worm, and FIG.
The figure is a line diagram for explaining the difference between the reed unit and L2 of the multi-lead worm, Figures 4 (,) to (g) are partially enlarged cross-sectional views for explaining the operation of the embodiment, and Figure 5 The figure is a flowchart for explaining the operation of the embodiment. 1...Multi-lead worm, 2...Screw thread. 3.4...Lead surface, 5...Spindle center, 6...
Tailstock center, 7... Main spindle, 8... Headstock, 9... Tailstock, 10... Table. 11...first motor, 12...grindstone, 13...
Feed nut, 14...Feed screw, 15...Bed,
20... Second motor, 21... NC device, 22.
...MDI. Fang diagram ((2) Diagram -) Diagram (C) Lock (9) Niirokotsui] 2 α mouth] ■ Ko E mouth 7 Koni; - Horizontal 11 = Gate

Claims (1)

[Scope of Claims] 1) In a method for grinding a multi-lead worm in which the lead on one lead surface of the screw thread is different from the lead on the other lead surface, each of the leads is ,
The initial position of the table at the start of grinding, the table stroke, the amount of movement of the grinding wheel between the one lead surface and the other lead surface (offset amount), the number of feed movements of the grinding wheel from the start of grinding to the end of grinding (number of shifts) ) etc., enter each specification,
A grindstone having a width smaller than the grinding groove of the screw thread is inserted between the one lead surface and the other lead surface, and while the grindstone is reciprocated by the number of shifts, both lead surfaces are NC characterized by automatic thread grinding
How to grind a multi-lead worm on a grinding machine. 2) In a grinding device for a multi-lead worm in which the lead on one lead surface of the thread is different from the lead on the other lead surface, a grinding wheel whose width is smaller than the grinding groove of the thread and the multi-lead worm are driven to rotate. a first motor for reciprocating the table, a second motor for reciprocating the table, and an NC device connected to both of the motors and controlling the operations of the two motors in accordance with the respective commands;
The NC device includes each lead, the initial position of the table at the start of grinding, the table stroke, the amount of movement of the grindstone between the one lead surface and the other lead surface (offset amount),
It is composed of an input means for inputting various specification values such as the number of times the grinding wheel moves from the start of grinding to the end of grinding (number of shifts), and the narrow grinding wheel is connected to one lead surface of the screw thread and the other lead surface of the thread. The grinding wheel, the first motor, and the second motor are controlled by the NC device based on the command values of the input means while sequentially engaging the grinding wheels, and both lead surfaces are thread-ground to a predetermined lead. A multi-lead worm grinding device for an NC grinding machine.