GB2029459A - Building motions - Google Patents

Abstract

A package building process comprises sequential formation of an upper and a lower tapered portion at the ends of a cylindrical central portion of the package. The upper portion is formed by a composite sequence of relative motions hs while the lower portion is formed by a constant regressive motion hi. A device for performing this process comprises means for carrying out relative displacements between spindle support and means for distributing the yarn about the support, and separate means for forming the central portion and upper and lower tapered portions of the package. Two separate cams are provided actuated by different motor or transmission means for programming the formation of the upper and lower portions. <IMAGE>

Description

SPECIFICATION Process and device for making yarn packages The present invention relates to a process and device for making yarn packages by winding yarns about essentially cylindrical tubes or tubular cores, in particular for the formation of bobbins or cops.

The process and device according to the invention are used in the course of the final stage of the spinning process, in order to obtaih the yarn in the form of a package which is salable and subsequently usable in weaving.

The process and the device according to the invention are adapted for making cops of practically any type of yarn, but are particular iy advantageous for packaging artificial yarns (such as rayon or cellulose acetate) and synthetic yarns (such as polyamides, polyesters and the like).

Commonly, the cops are prepared by winding the yarn, preferably but not necessarily produced in the form of a continuous yarn, about a cylindrical tube mounted on a rotating spindle, according to a certain sequence of yarn distribution, the yarn being fed by means of a ring or any suitable twist imparting device, to form a yarn package having the shape of a cylindrical bobbin with frustoconical ends. In some cases, as explained hereinafter, the package has only one conical end (the upper end) whereas its base is planar and is associated with a plate or disk which forms the base of the tube.

The winding sequence is defined by a predetermined succession of relative displacements between the spindle and the yarn feeding means (e.g. the ring), due to relative displacements between the spindle bar (which supports and actuates a plurality of spindles) and the ring bar (which supports a correspondingly plurality of rings). Said sequence of alternating motions causes the distribution of the yarn in the desired cylindrical-frustoconical geometry of the cop, with the desired conicity.

The winding of the yarn is usually carried out according to one or the other of two fundamental package build-up types, which will be called "regressive closure winding" and "differential winding". Both of these types permit formation of (not taking into account the yarn crossings which are outside the field of the invention) a cylindrical winding over a certain portion of the height of the cop, whereas at the two ends of said portion the diameter of the winding progressively decreases during its formation until it reaches that of the tube support.

Both these types have advantages and drawbacks, which will discussed hereinafter in the course of the following detailed description of embodiments of the invention, with reference to the attached drawings, wherein: Figure 1 (A, B, C and D) schematically represent, respectively, a cop, a graphic illustration of the distribution of the layers of yarn progressively wound by the "regressive closure" winding procedure, the scheme of the sequence of the alternating motions producing said distribution, and, finally, a mechanism which produces said motions and therefore said distribution; Figure 2 (B, C and D) likewise represent, respectively, the yarn layers distribution, the alternating motions sequence scheme and the device which can be used for making a cop (corresponding to that indicated in Fig. 1(A)) by the "differential winding procedure";; Figure 3A represents fragmentarily in lateral view and with greater graphic evidence, a cop packaged according to the invention; Figure 3B represents the scheme of the yarn layers distribution in the cop of Fig. 3A; Figure 3C analogously represents the scheme of the alternating motions sequence which is followed when operating according to the invention; and Figure SD represents, with certain constructive simplifications and schematizations, a device which can be used according to the invention to obtain the cop package of Fig.

3A, according to the scheme and with the distribution indicated in Figs. 3C and 3B respectively.

In the several figures attached hereto, 10 generally indicates a cop of yarn wound about a tube 1 2 which is supported and rapidly rotated about a vertical axis a-a. Tube 1 2 is mounted on a spindle, actuated by known means, not shown, and is supported, together with a plurality of other similar spindles, on a spindle bar. In principle a cop 10 of this kind has a predetermined axial dimension or total height H (e.g but not necessarily in the order of 400 mm), which comprises a cylindrical central portion and two frusto-conical ends, upper end 1 4 and lower end 16, the heights whereof may be equal or may be different as shown, and are being indicated by hs and hi respectively.The yarn is fed to the winding by known means, typically a ring 1 8 mounted on a bar 20, as schematically indicated in Fig.

1(A).

These winding means are well known in the art and constitute an integral portion of spinning machines, spinning-twisting machines and the like. The geometry of the package is determined by a sequence of alternating displacements, along the respective axes a-a, of ring bar 20 with respect to the spindle bar.

Said sequence and the means for obtaining it will be described hereinafter.

At the end of the wind-up process, or when the cops have been completely built-up they are doffed, viz. they are removed from the spindle bar and substituted with empty tubes about which the yarn winding operation is started once again. According to the modern art, the spinning or twisting machine is never stopped, and the doffing is effected by successively acting on different cops: this is essential when continuous yarn chemical fibres are processed.

An event which inevitably occurs is the breaking-off of a yarn during the winding. In this case the incompletely wound tube is removed from the spindle bar and substituted with an empty tube about which the process is re-started. Obviously in such cases at least two incomplete and inevitably incorrectly wound cops will form, from which the respective yarns will be subsequently removed and transferred to another package, with the elimination of the yarn which cannot be properly used, which become waste.

Generally considering the building-up of a cop, the largest diameter thereof, more precisely of its cylindrical central portion, is attained when a sufficient number of layers of yarn coil has been conveyed onto the tube.

The conicity of the upper end 14 and of the lower end 1 6 of the cop is obviously obtained by conveying about the portions having the heights hs and hj (better seen in Fig. 3A) a progressively decreasing number of layers.

The complete formation or build-up of the cop requires a period of time (obviously depending on the yarn count and cop dimensions) which is in general several hours and even several tens of hours.

If the cop has conical ends (as shown in Figs. 1(A) and 3A) its formation must follow a winding sequence which will lead to the formation of said ends.

It is further to be kept in mind that the yarn must be removed from the cops to be subsequently processed in textile machinery. In general, said removal is effected by drawing the yarn off axially (as schematically indicated by S in Fig. 1(A)), which requires that the successive coils become easily and promptly freed from the winding. In the case of the unwinding in "double twist" twisting machines, the axial drawing off is completed by passing the yarn into the spindle axis and therefore in a rotating system (known per se and not shown) which imparts to the yarn a further twist. Even then, the condition of the axial drawing off is not substantially modified except as to the times and the (considerably lower) speeds with which the coil move away during the drawing off.

The distribution of the coil layers, required to obtain the desired cop geometry, may be obtained, as has been said, by means of two winding systems, regressive closure and differential.

Considering firstly the regressive closure winding, reference should be made to Fig. 1.

To obtain a package as shown in Fig. 1(A), the package build-up begins by distributing the yarn over the entire height H of the cop and progressively reducing the height of the axial distribution of the coils down to a final value h in the cylindrical part, which value is attained at the end of the build-up time T. The highest number of coil layers is contained between the two levels L' and L" of the bases of the two conical ends 14 and 16.

The coil layers are thus distributed in the cross-sections of the cop (on planes which contain its axis a-a, as schematically indicated in Fig. 1(B). The sequence of the alternating motions of the spindle bar is schematically shown in Fig. 1(C), wherein the parallel and adjacent segments, each of which represent an axial displacement, but of which only a limited number is shown for reason of illustration, the actual number being much greater, are contained within an isosceles trapeze (which may be asymmetrical, as shown, owing to the different heights hs and h) the bases whereof are in represented by H and by h respectively.

A distribution of this kind can be obtained by means of a mechanism as schematically represented in Fig. 1(D). Said mechanism comprises in principle a pair of cams, e.g. but not necessarily axial cams, 22 and 24, actuated by shaft 26, actuated in turn e.g. by a motor 28 through a reducer 30 having a very high reduction ratio, as these cams must take the entire build-up time T to complete their useful rotation (viz. to travel over their active profiles). The motions of the spindle bar may be mechanically controlled by the cams themselves directly, or preferably through suitable hydraulic drives associated with microswitches and the like. A drive of this type will be briefly described with reference to Fig. 3D.

The essential rules of the differential winding are schematically represented in Fig. 2. In this case, the yarn coils are alternatively distributed over the entire height H of the cop to be packaged, but with a distribution which constantly covers the height h of the cylindrical portion and alternatively extends, with progressively advances at one end while retreating at the other, until it reaches the limits a 11 and 1" of said maximum height H, the sequence of the displacements corresponding to the scheme of Fig. 2(C). The total build-up a time T (which may even be, as hereinbefore stated, in the order of tens of hours) is subdivided into a sequence of partial times t (each generally in the order of one or a few minutes) in the course of each of which the yarn distribution progressively extends from limits 1' and 1" to limits L' and L" and viceversa, twice to cover the said partial heights hs and hi.

The yarn coil layers are therefore distribut ed, in the axial cross-sections of the cop, as schematically indicated in Fig. 2(B). Over the entire height h of the cylindrical portion said layers overlap one another and are distributed on cylindrical surfaces. Above and below the levels L' and L", said layers alternately extend till they reach the end levels 1' and 1". For graphic clarity, the scheme of Fig. 2(B) only reproduces the layers which are obtained at the vertices of the shaded upper and lower triangles of the distribution of Fig. 2(C), whereas, in reality, the wound coils occupy only a portion of the conical ends of the cop, which portion varies from a maximum (at the levels 1' and 1") to a minimum (at the levels L' and L").In any case, in the course of every partial packaging time t, the successively wound coils cover the whole of the height H of the cop which is being produced.

As mentioned hereinbefore, each of these traditional types of cop winding has advantages and drawbacks, and precisely: -a cop obtained by the regressive closure procedure (Fig. 1) can be unwound in an excellent manner even at high speeds. This is because the coils which are successively drawn off, as indicated by S in Fig. 1(A), are always unwound from cylindrical layers and therefore do not encounter any resistance in leaving the winding, or more precisely, the resistance is rigorously constant and in general very small, which means that there is a constant unwinding tension and therefore an uniform construction of the products and the fabrics produced from the cops, which produces an uniform dye absorption of the same.

This advantage is maintained even when operating on double twist twisters; -in the conical portions 14 and 1 6 practically all the wound yarn is visible, at least in correspondence of the end coils of each overlaid cylindrical layer. If e.g., processing irregularities have occurred (it should be remembered that the processing lasts several hours) they are visually evidenced by rings which show on said frustoconical portions; the finished cops can therefore be checked as to uniformity of quality, which permits an efficient and timely selection.

On the other hand, the regressive closure procedure is not free from drawbacks. E.g., if the yarn breaks during the winding, the lighter cops which form after the operation is re-started can be used only within the production factory because the re-starting begins from an initial height H smaller than the original one, which requires particular devices and manipulation to empty the cops; -the wound yarn, being totally exposed (in its outer coils of each layer) in the portions 14 and 16, may be totally damaged during handling (which generally affects its upper portion 14), particularly in the transportation, packaging and re-working stages; coils may become disarranged or fall off at the point at which the damage occurs, and then the good yarn which lies outside said point will have to be eliminated as waste.

On the other hand, when differential winding (Fig. 2) is adapted, it becomes possible to use reduced weight cops (obtained after restarting after breakages) because the yarn always covers the entire useful height H of the support; -the packages can be manipulated more safely and any possible surface damage suffered by the cop may be eliminated by unwinding only the outer layers of the winding (in principle, the layers formed in a single partial time), therefore with a minimum loss of yarn to waste.

-Probably the most significant drawback of these packages is found in the unwinding, particularly at high speed. This is because when the coils which occupy the lower frustoconical portions 1 6 of the cop are axially unwound, said coils, the diameter of which is smaller than that of the overlaying cylindrical portion, must spread out and climb back over the overlaying portion. This causes repeated and periodical increases of the yarn tension during the unwinding, which increases become considerable at certain speeds (e.g. are in the order of 50 gr at 600 m/min) and become more severe if the yarn is twisted on double-twist spinning machines. Said tension variations may cause defects in the fabrics produced from the cops, and more or less severe differences in dye absorption.

Packaging by differential winding is carried out in principle by means of a mechanism as schematically shown in Fig. 2(C). This mechanism comprises e.g. two opposed cams 22', 24' actuated by a shaft 26 driven by a motor 28 through a reducer 30'. Said reducer 30' has a rather low reduction ratio, since the cams 22' and 24' must complete a revolution in each of the partial times t. As schematically shown in Fig. 2(D), the profile of said cams is oriented and keyed in such a way as to impart to the spindle bar (directly and mechanically or, preferably, by suitable drives) alternating displacements, graduated in time, between the levels l'-L' and respectively L"-l", according to the diagram of Fig. 2(C).

To obviate at least in part the drawbacks of the differential procedure, an intermediate technical solution has been proposed and used according to which only the displacements which produce the upper frustoconical portion of the package are effected. In this case the displacement diagram corresponds to the scheme of Fig. 2(C), only in its upper portion, between levels I' and L' and as a consequence a cylindrical cop is obtained which has only one upper frustoconical portion 14. Such a bottle shape of cop with a plain base, may be formed exclusively about a support provided with a flat lower flange, since the winding is absolutely unstable in its lower portion. This type of support requires perfect centering and positioning on the spindle since irregularities even in the order of a very few millimeters may cause the formation of large amounts of waste.Then, processing and machinery maintainance and control difficulties arise, and as a whole difficulties and expenses are encountered both in the packages (including the supports) and in control and manipulation.

It will now be clear that the prior art systems for packaging cops and equivalent windings about a support, from which windings the yarn must subsequently be axially drawn off, the yarn coils leaving the surface of the winding (which is progressively exhausted) and being axially displaced towards and beyond the upper end of the cop, have each one several drawbacks, some of them very serious, which affect both the technique and the economy of the processing and the product quality and therefore in general lower the efficiency of the production.

The present invention provides a new process for packaging yarn cops for textile or equivalent use, of the type considered, which comprise a cylindrical or approximately cylindrical portion and essentially frusto-conical upper and lower ends. The words "upper end" are to be construed herein as meaning the end (generally directed upwards) through which and from which the yarn is unwound.

Further, the process according to the invention belongs to the category in which the geometry of the packaged cop results from the execution of a sequence of relative alternating motions, (in a vertical direction at least motions in the direction defined by the cop axis) of the spindle, and therefore the tubular support about which the yarn is wound, and the means (generally a "ring") by which the yarn is guidedly fed (in a manner known per se) to and about said support, said sequence determining a selective stratification of coils on at least in part cylindrical surfaces which overlap each other, in a number and with measures that are different at least in correspondence of the said frustoconical ends.

In this way packaged cops are produced which are free from some of the aforesaid drawbacks, both in the winding stage and in every successive processing, from the unwinding to the diverse control, transport, packaging and other operations, all the way to the final use of the yarn.

The invention also provides a device for carrying out said process, to obtain yarn cops having the aforesaid and other advantages, all as hereinafter defined.

The process according to the invention is characterized by the selective adoption of a winding procedure of the differential type for the formation of the tapered upper end of the cop, and of a procedure of the regressive closure type for the formation of the lower tapered end.

It is obvious that the said two distinct procedures, or fundamental types of yarn winding and cop build-up are incompatible with respect to the sequence of the vertical alternating motions of the ring or in general of the means for guidedly feeding the yarn coils about the support. Therefore, an object of the invention provides means for the selectively winding the yarn according to two distinct sequences respectively affecting the tapered upper and lower ends of the package.

An embodiment of the invention, as well as the advantages which derive therefrom, will now be described and discussed with reference to Figs. 3A, 3B, 3C and 3D, wherein the parts equivalent to those reproduced in Fig. 1 and 2 are designated by equal or homologous reference letters and numbers.

Let us consider the building up of a cop 10 as fragmentarily shown in Fig. 3A, through selective winding of a continuous yarn about a support or tube 12, said cop comprising a tapered upper end 14 and a tapered lower end 1 6 having heights hs and hi respectively, the bases whereof are adjacent to the bases of an intermediate cylindrical portion having the height h. The total height of the package is indicated by H, as in the previous cases.

Therefore, the yarns should be distributed about the support 1 2 in such a way that some of its coils extend over all the said height H.

Characteristically, the procedure according to the invention is carried out according to the diagram represented in Fig. 3C, wherein T indicates. the doffing time (in general some or even many hours). As is seen, this diagram extends rover an area having an asymmetrical contour inscribed in a scalene trapeze having bases (which are shown as vertical in Fig. 3C, as the cop axis is vertical in Figs. 3A and 3B) the larger of which has the height H at the beginning of the time T while the smaller has the height h + hs at the end of said time T.

The inclined side of the trapeze is a segment of the straight line which rises from the lower limit of the height H over the entire height hi of the lower taper 16.

The opposite side of the trapeze, perpendicular to its bases, is divided into a plurality of triangular areas having the height hs, distributed along the abscissae in as many partial times t (in general of the order of a very few minutes).

By comparing the diagram of Fig. 3C with those of Fig. 1(C) and of Fig. 2(C), one notices that the upper portion of the new diagram corresponds to that of a differential winding diagram, whereas the lower part thereof corresponds to that of a regressive closure diagram.

By following said sequence of yarn distribution of the height H of the package, and always considering the coils as arranged in layers, one obtains in the package itself a distribution of layers as schematically represented in Fig. 3B. The parallel layers formed in the cylindrical portion of the package are prolonged, while maintaining their parallelism, over all the lower tapered portion 16. Above the level L', or the level at which the upper taper 14 begins, the coil layers extend to cover (at least at one point of each partial time t) the winding which is being formed. In other words, the formation of the upper taper 14 is effected according to a differential procedure.

On comparing the diagrams of Fig. 1(B) and 2(B) with the new diagram of Fig. 3B, it is noticed that the tapered upper portion 14 and lower portion 1 6 of the new diagram correspond to the respective portions of the schemes of the packages obtained by differential and regressive closure winding respectively.

In Fig. 3A the package is graphically reproduced in such a way as to evidence (as far as possible) the fact that the upper taper 14 is formed by coils which cover the underlying ones, whereas on the surface of the lower taper 1 6 there appear rings corresponding to the lower (progressively receding) coils of the parallel layers.

The new package has therefore, characteristically, the combination of the advantages of the two classic known systems, without their drawbacks. Effectively, the upper tapered portion 14 (in correspondence to which the cops are generally handled) is protected and any possible damage may be eliminated by unwinding few yarn layers, whereas at the surface of the lower tapered portion 1 6 there may appear, in a clearly visible manner, the "rings" which indicate disuniformity of treatment or production of the yarn, over the whole of the package.

A particularly important feature, characterisits of the new package, is that its unwinding (by axial drawing off) may be carried out at the highest speeds and with maximum regularity. This is because all the coils belonging to all the layers may unwind and be drawn off without spreading out about portions having a larger diameter than that of the cylindrical layer from which the coils are removed. Actually the tension increases which are a drawback of the unwinding of cops formed by differential winding, appear only at the moments at which the coils belonging to the lower taper are drawn off, which does not occur, obviously, when operating on cops distributed according to the scheme of Fig.

3B. This advantage is even more pronounced when the yarn is unwound on double twisters.

On the other hand it is obvious that prior art devices do not permit operation with a sequence as in Fig. 3C, and in general with a succession of motions for the formation of the upper taper which is different from that for the formation of the lower taper. A device adapted to the production of a package according to the invention may be of the type exemplified in Fig. 3D and may comprise e.g.

an hydraulic system, exemplified by an hydraulic cylinder 40 the motions of the stem 42 of which are controlled e.g. by feelers 44 and 46, loaded by resilient means 48 and 50 respectively and associated with microswitches 52 and 54 respectively.

The micro-switches may be in turn actuated (by systems equivalent to those described in Figs. 1(D) and 2(D)) by cams, preferably but not necessarily axial, 22" and 24" respectively having however different profiles and rotating at different speeds, to complete the respective cycles in different time periods. In particular, cam 22" (which determines the motions leading to the formation of the differential upper taper 14) is actuated by a motor 28 through a reducing mechanism 30' having a relatively small transmission ratio, in order that the operative cycle of this cam be completed in a partial time t.Cam 24", which determines the formation of the regressive lower taper 16, is actuated e.g. by a shaft 26" and (not necessarily) by the same motor 28, through a reducing mechanism 30" having a high reduction ratio, in such a way that its cycle will extend over the entire total doffing time T.

The device of this embodiment comprises two opposed and coaxial cams and the shaft 26" which actuates the slow cam 24" is coaxial with shaft 56 actuated by reducer 30'.

However the cams or equivalent mechanisms which determine the motions sequence for the formation of the two tapers (characteristically, being of different types) may be or not be coaxial and may be different from those shown, and might be actuated by independent motors having variable appropriate speeds to adapt the machine for different total doffing times and/or for different partial formation times of the taper produced by differential winding, or in general better to adapt the machine to different packaging requirements. Similarly, the control and in general the actuating systems of the parts having different motions, on the mutaul relationship whereof the differentiated sequences characteristic of the process of the invention depend, may be different from those illustrated.

Claims (11)

1. Process for making yarn packages by winding yarns about essentially cylindrical supports, the packages including an essentially cylindrical central portion having the predetermined maximum diameter of the package and essentially frustoconical upper and lower tapered portions, the geometry of the package being determined by a programmed sequence of alternating displacements, in a direction parallel to the axis of the package, of the means for guidedly feeding the yarn about the support with respect to the means for carrying the support with respect to the means for carrying the support and imparting a rotary motion thereto, the sequence being completed in a total doffing time at the end of which the cylindrical portion reaches the predetermined maximum diameter, characterized in that it comprises different sequences for the formation of the upper tapered portion through and beyond which the yarn is intended to be removed by axially drawing it off, and for the formation of the lower tapered portion, the different sequences being adapted to produce, respectively differential and regressive closure winding of the yarn on the upper and lower tapered portions.

2. Process according to Claim 1, characterized in that the upper tapered portion of the winding is formed by a composite sequence of relative motions over the total height of the package, including a series of alternating motions following one another in a succession of partial times, and the lower tapered portion is formed by an essentially constant regressive motion lasting for the total doffing time.

3. Process according to Claim 1 or 2 characterized in that it comprises carrying out a sequence of alternating yarn distribution displacements in the upper tapered portion of the package, over an essentially constant height equal to the difference between the level of the top of the essentially cylindrical portion and that of the top of the upper tapered portion of the package, and concurrently carrying out an essentially uniform displacement between the level defined by the lower end of the lower tapered portion at the beginning of the packaging procedure, and the level defined b.y the lower end reached by the essentially cylindrical portion, at the end of the winding.

4. Device for forming yarn packages by winding yarn about a cylindrical support, the device including means for carrying out programmed sequences of relative displacements between spindle support and actuating means and means for guidedly distributing the yarn in coils about the support in spinning machines, twisting machines, and like textile machines, according to the process of Claim 1, characterized in that it comprises separate means for producing the formation not only of the essentially cylindrical central portion of the package, but also of the upper tapered portion of the package, on the one hand, and of the lower tapered portion of the package on the other, the means for producing the formation of the upper tapered portion effecting a succession of cycles of alternating motions each cycle of which is completed in a time which is a fraction of the total doffing time, and the means for producing the lower tapered portion effecting a cycle of alternating motions which cycle stretches over the entire doffing time.

5. Device according to Claim 4, characterized in that it comprises means for the formation of the upper tapered portion by effecting cycles of relative displacements, each in a sequence of times individually equal to a small submultiple of the total doffing time, and means for the formation of the lower tapered portion by effecting a single axial displacement over the total doffing time.

6. Device according to Claim 4, characterized in that it comprises at least two separate cams, one of the cams, which programs the formation of the upper tapered portion, being actuated in such a way as to determine a repetition of displacements in a sequence of partial times, and the other of said cams, which programs the formation of the lower tapered portion, being actuated in such a way that its cycle is completed over the course of the entire doffing time.

7. Device according to Claim 6, characterized in that it comprises a different motor and/or transmission means for actuating each of the two cams.

8. Device according to Claim 7, characterized in that it comprises cams actuated by different shafts connected to a single motor means through reducing gearings having different transmission ratios.

9. Device according to Claim 7 to 8, characterized in that it comprises coaxial cams actuated by coaxial shafts rotatively independent of one another.

1 0. Device according to Claim 6, characterized in that it comprises control means for imparting to the operative components of the machine the sequence of motions determined and programmed by means of the cams.

11. Cops formed by a plurality of yarn coils wound in a plurality of superimposed layers and constituting together a package the outer geometry of which includes an essentially cylindrical central portion and upper and lower tapered portions, characterized in that it comprises coils distributed in essentially cylindrical, parallel and coaxial layers which extend, without substantial alteration of their parallelism, over the whole of said central portion and then into the lower tapered portion, and into layers at least in part convergent and partially overlapping one another in the upper tapered portion.

1 2. Cops according to Claim 11, characterized in that the superimposed parallel layers which extend into the lower tapered portion terminate at progressively decreasing levels starting from the lower end of the winding to the base of the essentially cylindrical portion thereof, so that the lower coils of the layers appear at the surface of the lower tapered portion.