JPS62114818A - Method and device for manufacturing screw - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a screw by cutting a thread groove and then compressing and smoothing the thread surface, and an apparatus therefor.

(Prior Art and Problems) A method for producing screws of this type is already known from German Patent No. 854,291. With such a method, the thread surface is smoothed by compression grinding and precisely dimensioned. However, the above-mentioned publication does not describe how compression polishing and the tools used therefor are carried out.

Roll tools can also be used, as well as other surface smoothing applications.

Often such tools are large in size and are difficult, especially in the case of small screws. When compressing and smoothing small screws, the same amount of surface pressure must be applied as in the case of large workpieces, so it is usually not possible to obtain the desired surface quality if the roll device has a complex structure. Screws with precise dimensions and excellent surface quality require, in particular, screw transmissions that convert rotary motion into linear motion and vice versa. Screws for such applications require normal operating conditions even under severe conditions, for example under large radial loads or when being tilted relative to each other. In these cases, large adhesive or discontinuous frictions must never occur.

(Means, Actions and Effects for Solving the Problems) The object of the present invention is to provide a method for manufacturing a screw of the type mentioned at the beginning, which is inexpensive, precise, and has a smooth thread surface, and a method for manufacturing the same screw with a smooth thread surface. The goal is to provide equipment.

According to the present invention, regarding the manufacturing method to achieve this objective, a rough surface structure is formed in the thread dimension by cutting, and during compression smoothing, the area occupied by the peak (pointed end) is compressed. The surface structure is constructed by compressing and smoothing the surface structure in the plastic range to 30-80% of the total area.

In addition, as a device for this purpose, a compression smoothing tool suitable for the thread work to be machined is equipped with a dividing groove that extends almost horizontally to the thread groove and divides the tool into a machining end range and a machining start range. The starting range corresponds to the dimensions of the machined thread groove, and the finishing range has dimensions corresponding to the set dimensions of the thread, with a continuous transition between these two dimensions. Consisted of.

In the present invention, first, when a thread is cut using a tap or a die as is known in the art, a deliberately rough or rough surface texture is formed. This is particularly the case when the cutting edge of the tap is cut at a large angle compared to the normal acute configuration. Another method is to obtain a somewhat friable or coarse tissue! In order to use the IJ1wi alloy material, the workpiece may be subjected to a predetermined hardening treatment in advance. In both cases, after cutting the thread, the highly sharp microstructured surface will have groove-like properties also due to the cutting movement. The structure forms sharp peaks with raised valleys adjacent to each other.

In the next processing step, compression smoothing is carried out in the plastic range. In this case, it is important to consciously prevent compression (densification) of the surface so that at most the volume of the material in the peaks can be accommodated in the valleys. In order to ensure that the material deforms exclusively plastically without any compression of the structure in any case, according to the invention the compression smoothing of the surface is carried out only in parts, and the area of the compressed smoothed peaks is reaches 80% of the total area compressed and the remaining 20%
is the area of the valley. In that case, the compression-smoothed partial surface forms the supporting sliding surface of the screw, which sliding surface has an excellent surface quality and has precise dimensions despite only plastic deformation.

On the other hand, if a stronger compression treatment were to be performed, the entire material would be compressed if the troughs exceeded the limit of accommodating the material, ie exceeded the 100% limit. In this case, it is necessary to apply a very large pressure to the surface of the thread by means of the tool. Depending on the material of the workpiece, this pressure can rise up to several times the compressive force required for plastic deformation without compaction according to the invention.

The "compression smoothing" process of the invention described above is carried out, for example, with a roll tool. Since the forces required for deformation in the plastic range are small, this roll tool only needs to satisfy a few stability conditions and can therefore be made simple and small.

According to another feature of the invention, the thread flank surface is
It may be compressed and smoothed to the extent of transition to the top surface of the thread. In the case of special threads, for example trapezoidal threads, the non-supporting transition area is not compressed and smoothed. This results in a compression-smoothed 3
Two separate areas result: the thread flanks and the top surfaces on both sides. This division further improves the results in compression smoothing. This is because, due to the geometry, the compression process often takes place faster in the angular transition region than in a flat or nearly flat thread flank. Moreover, the compressive force is at least somewhat reduced and confined to the support surface.

Furthermore, according to another feature of the invention, the compressive smoothing is
This is carried out with sliding friction due to pressure inclined to the surface, in which case the surface structure ridges are deformed in bending and in parts by sliding. In this case, compression smoothing for the rolling device is achieved by means of ramps that stand up at an angle on the threaded surface of the tool under pressure. This movement of the thread surface relative to the inclined portion generates an inclined force on the thread surface, and this force partially bends the ridge portion in the direction of movement, and partially causes a sliding deformation transversely to the direction of movement. This process preferably takes place in the starting region of the slide. Another sliding range further improves the smoothed surface.

Compression and smoothing can be improved by supplying lubricant.

The above-described version of the method according to the invention is particularly advantageous with respect to the formation of tools, in particular for compression smoothing. In other words, the tool can be realized very simply and economically as a tool similar to a common screw tap. This advantage is, for example, several meters
This enables subsequent machining of very small screws of m. In other words, it is possible to apply compression smoothing according to the invention to an internal thread of, for example, a diameter of 5 mm in a simple and problem-free manner, in which case the tool becomes very thin, but there is no danger of it breaking. In this case, if the compression smoothness exceeds the above-mentioned limit of 100% and the compression process begins, so-called "galling" of the tool inevitably occurs. The method according to the invention completely eliminates this risk and nevertheless significantly improves the thread quality, where the dimensional accuracy and surface quality reduce adhesive friction and
The quality is uniform over the entire length of the screw. Of course, internal threads as well as external threads can be manufactured based on this method. The tool utilized for compaction smoothing according to the invention will be explained below with reference to an exemplary embodiment.

(Example) FIG. 1 shows a thread groove of a cut trapezoidal thread. In this case, a very rough surface structure 1 is created with sharp peaks 2 projecting from the surface and valleys 3 located between them. In the drawing, the structure wanders around the mean centerline 4 shown in FIG. The slight textural differences in the materials, the nature of the cutting edge of the tap and its cutting angle result in highly irregular structures with roughnesses of up to 10 μm RT.

The roughness is exaggerated in the drawings for ease of understanding.

FIG. 2 shows the trapezoidal screw in FIG. 1 after being subjected to compression smoothing in the next step. For the compression and smoothing process, a tap-shaped tool 5 shown in FIGS. 3 and 4, which will be described later, is used. The entire thread surface is smoothed up to the transition area 6 between the flank surface 7 and the top surface 8, in which case the tool 5 mentioned above has the dimensions indicated by the average center line 4 of the structure in FIG. The original dimensions 9 of the machined thread in FIG. 1 are indicated in dash-dotted lines in FIG. By compression smoothing processing,
The ridge 2 is deformed, the material part of the ridge becoming the trough 3.
Get inside. The total support surface of the smoothed partial surfaces is, for example, about 80% of the total area compressed.
The remaining approximately 20% is the area of the valley portion 3. In the transition area of the thread groove to the bottom surface 10, a slight excess material 1) in the form of a bulge occurs.

Next, the compression smoothing process will be explained with reference to an enlarged cross-sectional view of the surface structure shown in FIG. This compression smoothing step is carried out with tool 5 in FIGS. 4 and 5. In order to make the process easier to understand, the tool 5 will be explained first. This tool 5 consists of a tap-shaped shaft 12 with two separating grooves 13 extending symmetrically and parallel to the axis and orthogonal to a number of screw turns. All thread turns are divided by a separating groove 13 into two approximately semicircular parts 14, each of which has a machining start range 15 and a machining end range 16. The machining start range 15 of each semicircular portion 14 starts at the small diameter part that is the bottom of the separation groove 13, rises in a ramp (uphill trajectory) to the desired nominal diameter of the screw, and forms the machining end range 16 in a circular shape. It extends continuously to line 17. This is particularly the case in Figure 5, which is an enlarged detail of section A in Figure 4.
It can be clearly understood from the diagram. Lubricant is conveyed to the screw through the separation groove 13.

As already mentioned, the smoothing tool 5 is used to compress and smooth the machined thread in FIG. The surface structure to be processed after cutting corresponds to the enlarged view on the right in FIG. Its surface is rough and has prominent peaks 2 and valleys 3 between them. When screwing in the smooth tool 5, the crest 2 first comes into contact with the machining start range 15 of the first semicircular portion 14. Due to its slope, mountain part 2 has
A compressive force F is applied which is inclined from the circumferential direction to the radial direction. As shown by the arrow at the peak 2, this compressive force F is applied to the trough 3 due to bending in some parts and due to the sliding of the material in some parts.
move it inside. When the end-of-machining region 16 is reached, the process in this semicircular section 14 is terminated, resulting in a smooth structure as shown on the left side of FIG. , the trough 3, which had been open until now, becomes narrower and becomes larger. The deformation takes place in the plastic range of the material. As the smoothing tool 5 continues to be screwed in, another semicircular section 14 follows and provides even better smoothing.

The illustrated smoothing tool is merely an example. It is also possible for the semicircular section of the first screw turn to be located at a small diameter and for the subsequent semicircular sections to be formed with successively increasing diameters. This allows the compression smoothing effect to be distributed over a wide area of the tool.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a sectional view of a trapezoidal thread after cutting, Fig. 2 is a sectional view of the trapezoidal thread in Fig. 1 after compression smoothing, and Fig. 3 shows a compression smoothing process. FIG. 4 is an enlarged cross-sectional view of the surface structure showing the deformation of the material therein, FIG. 4 is a cross-sectional view of a tool for smoothing an internal thread, and FIG. 5 is an enlarged detailed view of the portion in FIG. 4. 2・・・・・・・・・ Mountain part 3・・・・・・・・・ Valley part

Claims (7)

[Claims] (1) In a method of manufacturing screws by cutting a thread groove and then compressing and smoothing the thread surface, the cutting process forms a rough surface structure in the thread dimensions, and during compression smoothing, the smoothed ridges occupy A method for manufacturing a screw, characterized in that the surface structure is compressed and smoothed in a plastic range until the area becomes 30 to 80% of the entire compressed area. (2) Claim (1) characterized in that the thread flank surface is compressed and smoothed to the extent of transition to the thread top surface.
Method for manufacturing screws described in Section 1. (3) The method for manufacturing a screw according to claim 1 or 2, wherein the compression smoothing is performed with sliding friction by applying pressure inclined to the surface. (4) According to any one of claims (1) to (3), the peaks of the surface structure are partially deformed by bending and partially deformed by sliding. Method of manufacturing screws. (5) The method for manufacturing a screw according to any one of claims (1) to (4), wherein the compression smoothing is performed while supplying a lubricant. (6) A rough surface structure is formed when cutting the thread using thread dimensions, and the plasticity range is maintained until the area occupied by the smoothed peaks becomes 30-80% of the entire compressed area. In a device for compressing and smoothing a surface structure, a compression smoothing tool 5 corresponding to the threaded workpiece to be machined extends substantially transversely to the thread groove, and divides this tool 5 into a machining end range 16 and a machining start range 15. The machining start range 15 has dimensions corresponding to the dimensions of the machined thread groove, the machining end range 16 has dimensions commensurate with the set dimensions of the thread, and there is a continuous line between these two dimensions. An apparatus for manufacturing a screw, characterized in that the screw is provided with a transition section. (7) An apparatus for manufacturing a screw according to claim (6), wherein the separation groove 14 is formed as a lubricant passage.