DE2444653A1 - SOUND-ATTACHING LINING FOR A GUIDE TUBE FOR ROD MATERIAL - Google Patents

Description

24U653

Patent attorneys

Dr. Ing.Waiter AbHz

Dr. Dieter F. Morf

Dr. Hans-A. Brown"! ¹⁸ September 1974

S Munich 86, Pienzenaueretr. 2 «2272

POLYMER EXTRUSIONS, INC. 1701 West King Street, York, Pennsylvania, V.St.A,

Sound-absorbing lining for a guide tube

for rod material

The present invention relates to metal working machines and in particular machines in which a bar material of a certain length is fed to the machine, so that processing, such as thread cutting, drilling, broaching, providing with slots and the like. To the Work pieces is exercised, which can then be separated from the inner end of the rod material when the Editing is complete. In the present application, an automatic screw manufacturing machine is referred to as Example of the type of machine tools used in connection with the present invention.

Such machines may have a single spindle or a multiple spindle arrangement with the inner end a length of the rod material in a chuck

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becomes unofficial and the rod material rotates at holier speed, while the workpiece is being manufactured. The speed stands in direct relation to the processed material. With steel A speed of 800 rpm is used, while for brass a speed of between 210 and 2400 rpm is appropriate is.

The sections of the rod material, which are initially a extend a considerable amount beyond the machine, are held within elongated metallic! which in common machines have an average length of 3 m and which have an inner diameter, which is large enough to handle bar material of different diameters and profiles, such as Kund, square and hexagonal profiles and the like. It is therefore not necessary to change the guide tubes for the rod material depending on the diameter to exchange it, nor would such an exchange be expedient. Since the rod material is only on its inner The end is held while it rotates at high speed, the unsupported part of the rod material strikes as Result of the rotational forces around itself and rubs against the inner wall surface of the Kihrungsrohres, whereby the thereby caused Noise generation is so high that serious problems arise. It comes to nervous fatigue of the Machine operator with a corresponding drop in performance. The seriousness of this situation has since been Long recognized in the industry and there are federal regulations of the US Environmental Protection Agency which guidelines with regard to the permissible daily exposure to noise for operators of such machines, the permissible number of hours is directly related to the sound level (decibel).

For many years, attempts have been made to create optimal working conditions in which the sound level would be reduced to a negligible value, so

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that normal work activities including conversations is not disturbed. However, such attempts have not been successful.

The present invention relates to a sound-absorbing lining for a guide tube or the like for rod material, the liner being made from a very high molecular weight polyethylene.

The present invention also relates to a guide tube for rod material for use with metal working machines Or the like. Which consists of an elongated outer cylindrical metal pipe and an inner cylindrical sound-absorbing Lining consists of a thermoplastic material arranged coaxially in the outer pipe, wherein the portions of rod material through the liner and wherein a foamed thermoplastic material is present between the pipe and the liner is, as well as means for setting the lining.

The advantages of the present invention emerge from the following description in conjunction with drawings. Show it:

Fig. 1 is a partial perspective view of a conventional automatic Multi-spindle screw manufacturing machine from which the guide tubes according to the invention for the rod material . can be seen

2 shows a partially sectioned side view of a conventional guide tube for rod material,

3 shows a partially sectioned view of an inventive Lining for a guide tube,

FIG. 4 is a side view of the liner of FIG. 3, which from a helical band-like envelope composed of

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is surrounded by compressible material,

Fig. 5 is a side view of a locking ring to the To keep the liner within the guide tube,

6 shows an end view of the locking ring according to FIG.

7 is an end view of the liner and locking caps; which are arranged inside the guide tube, the final locking not yet taking place is,

FIG. 8 is an end view similar to FIG. 7, partially cut and on a larger scale, of the finished guide tube, with the locking done,

9 shows a longitudinal section through a modified embodiment of a lining for the guide tube,

10 is a vertical section of the modified embodiment of the invention along line 10-10 of FIG.

11 shows a vertical section of a further modified embodiment of a lining for a guide tube, and FIG

Fig. 12 is a longitudinal section of the further modified embodiment of the invention along line 12-12 of FIG.

In Fig. 1 is somewhat schematically the front end of a conventional automatic screw-making machine M with a plurality of Turret heads shown, which is provided with a number of guide tubes T for rod material, each guide tube serves to receive a section of a rod material to be machined, and the inner end of each section of the rod material is received in a known manner within a chuck, not shown.

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Each guide tube 10 (Pig. 2) consists of a relatively thin-walled tube, which is preferably made of stainless steel or a comparable material and has a length of approximately 3 m, the inner diameter of the pipe larger than the diameter of the machined Rod material is and is in a certain ratio to this, so that a free rotation of the rod material in the forward movement of the same in successive machining operations is possible when the respective end products (Screws) are manufactured.

During the machining operations, the rod material, which is only held at its front end, becomes high Rotated speed so that the rear or free end of the rod material is given an impact movement, and continuously Impacts against the inner surface of the guide tube take place, which leads to considerable sawing vibrations. Will If steel is used as the rod material, speeds of up to 800 rpm can be used. The rod material consists of Brass, speeds are in the order of magnitude of 2100 permissible up to 2400 rpm.

To prevent the rod material from hitting the inner wall the guide tube beats, and thus the transmission of sound vibrations to the guide tube and the machine To prevent this, the guide tube is to be fitted with a sound-reducing or sound-absorbing lining 11 arranged axially made of a plastic with sound-absorbing properties. Such linings are known and have been made from materials such as polyvinyl chloride (PVC), its sound-absorbing Properties are known. However, such materials have a relatively short service life and under operating conditions with speeds in the order of magnitude from 800 to 1000 rpm the service life of the pipe is such, that a weekly exchange must be made.

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Impact The Izod. Impact strength of a polymer strength: with a very high molecular weight at room temperature is greater than 173 cmkp / cm for a modified sample provided with a double notch. In a ballistic test performed at -540 c (-65 ° F), a very high molecular weight polymer plate, which was 2.54 cm thick, held a 0.45 inch ball which was fired at a distance of 7.6i. (173 cm kp / cm = J> 2 foot-pounds per inch)

Referring to Fig. 4, the liner 11 is the guide tube appropriately equipped with an outer covering in the form of a spiral-shaped wound band 12, which extends from one end of the tube to the other. This tape can be made from any foamed thermoplastic Material, such as polyurethane, exist, which is particularly suitable for the present application has proven. Such fabrics are easily compressible to 50% or less of their normal thickness, whereby a bandwidth on the order of 2.54 cm and one Tape thickness in the tension-free state in the order of magnitude of 0.63 cm is particularly suitable. As from the drawings As can be seen, a relatively narrow distance 13 is provided between adjacent turns of the tape, the purpose of which is described in more detail below. An adhesive can be used to make an accurate fix of the spirally wound tape 12 on the outer surface of the lining 11 to ensure.

As stated above, the inside diameter of the guide tube is not critical and depends on the diameter of the processed bar material. It is only necessary that enough play remains for the rod material, and both in the idle state and during operation, if there is a state of vibration or vibration within the guide tube. striking occurs. These relationships also exist with regard to the inner diameter of the lining 11 for the Guide tube.

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While PVC pipes do provide a certain amount of soundproofing, the costs of constant pipe replacement add up with the machine's working time lost as a result, the application of this known solution to the noise problem is impractical made.

By the present invention it has been found that a very high molecular weight polyethylene liner (ÜHMW) completely solves the problem of wear and tear and is sound-absorbing Exhibits data previously unknown in this and related fields.

Such pipe linings, which are expedient in continuous length, from a mixture of essentially equal parts of resins of very high Molecular weight produced, which molecular weights can range between 1 million to 6 million. A mixture of very high molecular weight resins, the respective molecular weights being 2.5 million and 4 million gives excellent results for the present application. With a mixture of resin particles, each portion having a molecular weight of 3 »5 million and an intrinsic viscosity of 20, optimal results are obtained.

Important mechanical characteristics of polymers with a very high molecular weight (polyethylene) are given below:

Hardness Rockwell R scale (test method D 785) - more representative Worth 64

Abrasion - For tests carried out over a period of 7 hours at a speed of 1750 rpm stood: were, the carbon steel had an abrasion of 100 (based on the volume of the during lost material testing), while the very high molecular weight polymer has a Has an abrasion number of 15.

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However, the outer diameter of the lining for the guide tube is critical, and if a spiral sheath is used, the difference between the inner diameter of the guide roller and the outer diameter of the lining should essentially correspond to the thickness of the sheath in the de-stressed state. If the lining above the side in the i ^ Ärungs ± ear IÖ centrally along -desselben according to FIGS. 7 * md 8 is £ Iilirt ₃ so the spiralfoinaige Uanhüllmig has collapsed bxl £ 50% of their thickness in the spanamingslosen state country it will be a close fit between the lining and the UBm guide tube. In such a too-tight anorantiaag, all the sound vibrations that arise when the stata material hits the inside of the lining are not transferred directly to the liriangs pipe, but are distributed to a large extent in the spiral-shaped Umhmlliang gedaagpüt edge, usually as a path of the cell-shaped Structure of the material S ₉ on which the tape used for the wrapper is made. Barüberhinaas serves to existing innerhallb Mihriangsrohrs the helical seam formed by the distance 13 between adjacent ¥ ind "hang the spiral Umhülliang voriiancLen 12 is to reduce transmission of sound from the vibrating Angen lining to further guide tube.

As can be seen, the lining ii has a lower one longer than the Mihrong's tube and is centered in it arranged so that it is at the same distance from the ends of the FCihriangsrohres, with the permanent locking of the Lining in place and to secure the same against unintentional! Longitudinal movement ¥ locking rings 14-provided each ¥ locking ring Ί4 consists of one Singbody with a marginal shoulder i5, which at one end of the guide tube rests when the locking ring, de ssen outer diameter, the inner diameter of the guide tube corresponds, is arranged in the latter. This ensures that there is close friction contact between the guide tube and

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opposing locking rings 14- enabled, wherein the inner end of each locking ring from the opposite end of the liner 11 is a sufficient distance to create a play with respect to the adjacent end of the liner through which expansion as a result of temperature changes
of the two dissimilar materials is included.

If necessary, each locking ring 14 with a
Bingmit 16, and after assembling the
Guide tube, the encased lining and the opposing locking rings, the guide tube 10 is rolled at each end of the same into the annular grooves 16 of the locking rings or pressed in some other way
as indicated at 17 in FIG. This creates a permanent lock between the guide tube and the liner. It is obvious, however, that frictional contact, for example between the locking rings 14 and the guide tube, is sufficient to ensure the assembled state of the arrangement, it being possible to provide a screw connection or another suitable connection between the locking rings and the guide tube, if necessary.

In the modified embodiment of the lining shown in FIGS. 9 and 10, the »lining 20 is in the
Inside the same provided with a flat spiral metal band 21, the inside diameter of which corresponds to the inside diameter of the lining, so that a completely smooth inner surface is obtained along the lining. This
Metal tape can be used during the manufacture of the liner
inserted, for example · by extrusion, and
ensures increased resistance to impacts, for example.

In a further embodiment of the lining according to FIG

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the pig. 11 and 12 is the lining JO with a number of ribs 31 running in the longitudinal direction. As can be seen, the outside diameter of the ribbed part of the lining is slightly smaller than the inside diameter of the guide tube 10, while the Liner located axially within the guide tube, a suitable polymeric material which in situ to a Foaming and expansion leads, under suitable pressure, into the annular space between the inner diameter of the guide tube and the outside diameter of the finned liner. This imported material results in the continuous annular layer 32 which extends the entire length of the liner and Attenuates sound vibrations that arise during operation of the arrangement within the lining.

When testing from a very high molecular weight polymer existing lining according to the invention, taking into account the preferred embodiments According to FIGS. 2 to 8, the system was on a four-spindle machine using a 3 / ^ inch hexagonal steel bar Installed. The machine equipped in this way was put into operation and worked with one Speed of 800 rpm. Periodic inspections were carried out over a period of more than 3 months, whereby No excessive wear was found on the inner surface of the liner. At the same time one was executed in the same way Machine tested with standard guide tubes without lining. There was also another test with a third Machine carried out, which was equipped according to the invention, but no spiral-shaped for the lining Wrapping was provided. In this machine, the liner was in direct contact with the inner surface of the guide tube.

Acoustic measurements were made in the vicinity of all three

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machines made »; It was found that in the machine without the use of the spiral-shaped envelope, the sound level on the guide tube was about 18.5 decibels lower than on the standard machine. The computational evaluation showed that the sound level at the Eührungsrohr for most frequencies below 4000 Hz lower than the sound level maintenance on the machine, the sound level of the modified Haschine, wherein the spiral wrap ₃ was used was 81.5 ÖBÄ. in the Yergleieh to a sound level of 103.5 «over for the machine in worm version. The noise reduction achieved by the modified machine was therefore 22 dB. This very substantial reduction in sound level has brought the sound level well below the permissible values under federal regulations issued by the Occupational Safety and Health Administration in the USA.

The prescribed limit values are listed in the table below :

Workplace limit value e

Sound Level Allowable Times Continuous

in decibels

every 90 dBA * unlimited

90 - 92 dBA, 6 hours

92 - 95 dB 4 hours 95 - 97 dB "'3 hours

97 - 100 dB - 2 hours

100 - 102 & b 1.5 hours

102-105 dB '. 1 hour

105 - 110 dB 0.5 hours

110 - 115 ÖB 0.25 hours

above 115 dB none

* A gives the sound level in decibels as it is determined by a sound ^{meter, which is measured with a filter with 11} A ". Such a filter only takes into account the sound at frequencies below 1000 Hz to a certain extent. The reference pressure was 20 Micronewtons per square meter. {1 Newton = 0.1019716)

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A standard calibrated sound meter with microphone, amplifier and filter was used as the sound meter Measurement of sound pressure values with characteristics according to ANSI standards S1.4 (1971) are used (ANSI - American National Standards Institute). When calculating sound pressure values in decibels, the reference pressure must be specified, where

the standardized reference pressure is 20 micronewtons per m. This Sound pressure reference value corresponds to the sound pressure of a 1000 Hz tone, which for a young person with normal Hearing would just be audible.

As already mentioned, the test of a machine in normal design showed a sound level of 103.5 dBA. As those listed above by the U.S. federal agencies permitted time values for noise exposure would be the permissible continuous working time (without Break) limited to 1 hour. In a machine with a lined guide tube according to the present Invention provided, the sound level fell to 81 1/2 dBA, which is a value at which a constant occupation during a whole working day without the operator becoming unusually fatigued suffers or is exposed to possible hearing loss as a result of exposure to excessive sound levels.

The invention provides a new guide tube for rod material is provided, which is designed for use with automatic metalworking machines _# Bowie, has a new liner for such tubes (or an assembling method) which can be economically produced a long life and noise level during operation of such Reduces machines to a value that was previously unknown in this and related fields.

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Claims (16)

patent claims 1. Sound-absorbing lining for a! Guide tube or Like. For rod material, characterized in that the lining is made of polyethylene with a very high molecular weight consists. 2. Lining according to claim 1, characterized in that the polyethylene is made of a very high molecular weight Resin particles that have a molecular weight of about 3.5 million and an intrinsic viscosity of about 20 have. 3. Lining according to claims 1 or 2, characterized by an outer spiral-shaped envelope which consists of consists of a band that can be joined together, which consists of foamed thermoplastic material. 4-. Lining according to claim 3j, characterized in that the material for the spiral wrap is polyurethane. 5. Lining according to one of claims 1 to 4-, characterized characterized in that the inner surface of the liner is provided with a flat spiral metal band. 6. Lining according to claim 1 or 2, characterized in that that the outer surface of the lining with a number of longitudinally extending outward protruding ribs is provided. 7. Guide tube for rod material for metalworking machines or the like., Characterized by an elongated outer cylindrical metal tube and an inner cylindrical one Sound-absorbing lining, which consists of thermoplastic material, which is coaxial in the outer pipe - 13 5098U / 0335 is attached and through which sections of rod material can be fed, and by a foamed thermoplastic Material which is arranged between the guide tube and the liner, as well as an arrangement, to secure the liner in place. 8. Guide tube according to claim 7 »characterized in that the inner cylindrical sound-absorbing lining Very high molecular weight polyethylene. 9. Guide tube according to claims 7 or 8, characterized in that that the foamed thermoplastic material consists of a foamed thermoplastic layer, which surrounds the liner. 10. Guide tube according to one of claims 7 to 9, characterized marked that the outer surface of the liner equipped with a number of evenly spaced, longitudinally extending ribs with the outer diameter of the ribbed liner being slightly smaller than is the inside diameter of the outer tube, and the foamed thermoplastic layer that makes up the liner surrounds, is formed in situ and under pressure within the outer tube. 11. Guide tube according to claims 7 or 8, characterized in that that the foamed thermoplastic material is in the form of an envelope consisting of a compressible spiral band and which is attached to the outer surface of the liner and extends from one end of the same extends to the other, the liner being less than the length of the outer tube has, and the ratio between the inner diameter of the outer pipe and the outer diameter of the liner with a spiral covering is such that - 14 - 5098U / 0335 244A653 a compression of the envelope in the order of magnitude of 50% is required to have a tight friction fit of the liner when it is inserted into the outer metal tube, with means for holding the Lining is present in the outer metal tube to allow longitudinal movement between the lining and Metal pipe to prevent. 12. Guide tube according to claim 11, characterized in that adjacent turns of the spiral sheath are spaced from each other to create a spiral air space within the outer tube. 13. Guide tube according to one of claims 7 to 12, characterized characterized in that the inner surface of the liner is provided with a flat spiral metal band is. 14. Guide tube according to one of claims 7 to 13, characterized characterized in that the foamed thermoplastic material consists of polyurethane. 15. Guide tube according to one of claims 7 to 14, characterized characterized in that the arrangement for holding the liner in the outer metal tube consists of an annular body consists, which is received by each end of the outer tube, the outer diameter of one each ring body complementary according to the inner diameter of the outer tube while achieving one tight friction fit is sized and each ring body is' in the outer tube by a sufficient amount extends to have a game against the adjacent end of the liner, which is a thermal expansion in the event of temperature changes of the two dissimilar materials, each ring body being an expanded one - 15 -509814/0335 24U653 Has ring shoulder, which in the assembled state 'of the arrangement in each case at opposite ends of the outer tube. 16. Guide tube according to claim 15 »characterized in that that each ring body has an outer ring groove, and the outer metal tube is pressed into this ring groove is used to lock the outer tube and the ring body together. - 16 - 50981 4/0335