GB2025840A

GB2025840A - An Apparatus for Cleaning Spinnerets

Info

Publication number: GB2025840A
Application number: GB7920117A
Authority: GB
Original assignee: Akzo NV
Current assignee: Akzo NV
Priority date: 1978-06-09
Filing date: 1979-06-08
Publication date: 1980-01-30
Also published as: BR7903627A; IT7949335A0; FR2428089A1; IT1116550B; FR2428089B3; GB2025840B; MX147315A

Abstract

An apparatus is provided for cleaning spinnerets fitted in spinning machines. The apparatus comprises at least one cleaning blade (3) which is movable in a plane parallel to the surface of the spinneret and has one side (24) running parallel to the surface of the spinneret in contact therewith. The side (24) is in the form of a planar face. Each cleaning blade (3) is arranged to be pressed against the surface of the spinneret with an adjustable force by springs (18) or the like. Each cleaning blade (3) is movably arranged with all its points on tracks of similar shape and similar path lengths. The apparatus has positively acting guide means (15).

Description

SPECIFICATION An Apparatus for Cleaning Spinnerets Spinnerets, in particular those used in melt spinning, generally have to be cleaned at the start of the spinning operation and regularly thereafter, as well as during the occurrence of sudden interruptions in spinning which can be caused by oligomers, thermally decomposed melts and the like settling on the spinneret holes. In most cases, this cleaning operation has to be carried out without interrupting the flow of melt through the spinneret and without removing the spinnerets from the spinning machine for this purpose.

Hand-operated spatulas of the type known, for example, from US Patent No. 3,341,945 are devices which are well known and widely used for this purpose. Since the pressing force with which these spatulas are pressed on to the surface of the spinneret during cleaning of the spinneret as well as the guidance of the spatulus over the surface of the spinneret depend on the handling by the respective operator, it is easy to damage the spinneret. The duration and success of the cleaning process also depend on the skill and ability of the operators.

An apparatus is known from US Patent No.

3,804,569, in which a spatula is arranged on an arm which is rotatable about a shaft. With this apparatus, the spatula can only be activated if the shaft of the apparatus has previously been screwed in a screw-threaded hole which is provided in the spinneret especially for this purpose. In addition, it is not possible to adjust the pressing force between spatula and spinn-eret to a precisely defined value in this process.

It is desirable to overcome these disadvantages, and accordingly an object of the present invention is to provide an apparatus which allows spinnerets, particularly those used in melt spinning, to be cleaned in a faster and easier manner than hitherto, while taking maximum care of the surface of the spinneret and the holes in the spinneret. This apparatus should also enable unskilled personnei to clean a plurality of spinnerets reliably and rapidly to a uniform standard.

According to the invention there is provided an apparatus for cleaning spinnerets fitted in spinning machines in the operation condition, the apparatus comprising at least one cleaning blade which is movable in a plane parallel to the surface of the spinneret and having one side running parallel to the surface of the spinneret in conract therewith, wherein the said side of the or each cleaning blade is in the form of a planar face, the or each cleaning blade is arranged to be pressed against the surface of the spinneret with an adjustable force, the apparatus has positively acting guide means, and the cleaning blade or blades is or are movably arranged with all their points on tracks of similar shape and similar path lengths.

In contrast to the known apparatuses, the cleaning blades in the apparatus according to the invention do not therefore rotate about a common axis lying inside or outside the blades but instead, perform a circling movement in which each point of the or each blade circles about its own axis or moves to and fro over a specific equally long distance.

Apparatuses having an appropriate number of correspondingly dimensioned round cleaning blades have proved suitable for cleaning spinnerets in which the openings are arranged, for example, in one or more circular arrays of holes, while apparatuses having an appropriate number of correspondingly dimensioned and arranged straight cleaning blades have proved suitable in spinnerets having holes arranged, for example, in rows.

The apparatus according to the invention is suitable not only for spinnerets having circular openings of a specific size but also for spinnerets with openings of any other shape and/or size.

In order to ensure that the cleaning blades always rest on the surface of the spinneret, it is advantageous to join the blades to the driving shaft, for example by means of a ball and socket joint or cardan joint. The adjustable pressing force of the cleaning blades can be achieved in a simple way using elastic members such as compression and/or spiral springs.

The design of the side of the cleaning blades contacting the spinneret surface in the form of a planar face has the advantage that, provided a suitable material is used, the cleaning blades need not be reground even after prolonged use because they regrind themselves during the spinneret cleaning operation.

Advantageously, the apparatus according to the invention is sufficiently light and manageable to enable it to be carried from spinneret to spinneret in a convenient and simple manner by an operator and placed into the correct operating position quickly and simply. As it is advantageous for good cleaning of the spinnerets to place the apparatus according to the invention as far as possible always in the same position in the case of each spinneret to be cleaned, the apparatus is advantageously provided, for example, with at least two projecting bolts or pins which can be introduced positively into holes each arranged and dimensioned accordingly in the region of each of the spinnerets on the spinning machine.

However, the surface of the spinnerets to be cleaned frequently lies in a different plane from, for example, the covering or insulation of the spinning machine. The projections and recesses thus produced in the region of the spinnerets can also be used as guides for always bringing the apparatus according to the invention into a precise position if the apparatus according to the invention is designed accordingly. If a guide of this type is designed functionally, it is not necessary to fix the apparatus according to the invention in an additional different manner but, instead, it is sufficient if the operator merely holds the apparatus in the operating position by hand during the cleaning of the spinnerets.

An embodiment in which the electric drive motorforthe cleaning blades is joined to the cleaning blades by means of a short rigid driving shaft has the advantage of being compact and therefore easily manageable. However, depending on the weight of the motor, an embodiment of this type can, in some cases, quickly tire the operator if it is used frequently or constantly. In order to prevent this from happening, it is possible, for example, to arrange an embodiment of this type movably and drivably on a movable frame or on a suspended track running along the spinning machine and additionally to compensate the weight of the apparatus wholly or partially by suitable counter weights.

An embodiment in which the drive motor for the cleaning blades is mounted on a movable frame and the cleaning blades of the apparatus according to the invention are set into motion by this motor by means of a flexible shaft has also proven very convenient and easy to use, inter alia because of its low inherent weight.

The cleaning blades can be straight or circular or can have any other suitable shape, depending on the arrangement of the spinneret openings in the spinnerets, each cleaning blade being provided with one, two or more than two rows of spinneret holes.

The most rapid cleaning method is obviously achieved if each row of spinneret holes is provided with only one cleaning hole. If the rows of spinneret holes are arranged very close together, such an allocation of the cleaning blades may however lead to an arrangement of the cleaning blades which is too tight for satisfactory and uninterrupted cleaning of the spinnerets. The most suitable allocation of the cleaning blades can however be determined quickly by very simple tests.

If several cleaning baldes are used, it is advantageous to arrange them over a common base plate which should advantageously be prevented from twisting about its centre. This prevents pellets or spun yarn formed during the cleaning of the spinnerets charged with melt from being wound by the cleaning head and then having to be removed again in an inconvenient manner. If this common base plate for the cleaning blades is driven by a crank or eccentric pin of a rotating shaft, the base plate and, with it, the cleaning blades perform a simple to and fro movement or a circling movement corresponding to the eccentricity of the pin, depending upon the type of engagement and guidance of the pin in the base plate. With both types of movement, all points of the base plate and the cleaning blades describe paths which are of the same shape and size in each case.

If the apparatus according to the invention is used uninterruptedly or is only interrupted briefly, the cleaning blades heat up markedly, frequently making it difficult to clean the spinnerets satisfactorily and, under certain circumstances, even making it impossible. In such cases, it is advantageous and generally sufficient to provide a device for cooling the cleaning blades, for example in the form of a fan, with which the cleaning blades are advantageously cooled before the next spinneret is cleaned. An embodiment in which the cleaning blades are cooled by one or more Peltier cooling elements has proved particularly useful.

The intermediate spaces formed between the cleaning blades should, as far as possible, be sufficiently large to make room for the pellets or spun yarn produced when the spinneret is running during a cleaning operation. The volume of the intermediate space is preferably adapted to the operating parameters and requirements by suitable dimensioning of the height of the cleaning blades in which, as already described above, the number size and arrangement of the cleaning blades is based on the number and arrangement of the spinneret holes.

A cage-like housing or a grid-like plate which only has slits for the passage of the cleaning blades, the slots being adapted very accurately to the shape and size of the cleaning blades, has proved suitable for cleaning the blades and the intermediate spaces between them of pellets and adhering solidified melt. Wheri the apparatus according to the invention is in the rest position, the blades are located, in this embodiment, inside this housing or beneath the grid-like plate so that the housing or plate also protects the cleaning blades from damage. Before the cleaning of a spinneret commences, the cleaning blades in this embodiment,are moved outwards through these slits in the housing or the plate to the operating position.Upon completion of the cleaning operation they are retracted again and, in the process, the melts adhering to the cleaning blades and the pellets which have collected in the intermediate spaces are scraped off and can be introduced into a waste container.

The size of the apparatus according to the invention is not subject to any limits within the range of conventional industrial dimensions, but it is advantageous to adapt it to the size of the respective spinnerets or spinning machines. The thickness of the side of the cleaning blades lying on the die surface to be cleaned should, however, be as small as possible. Conventional blade widths are of the order of 1 mm.

When selecting a suitable material for the cleaning blades, care should be taken not to select a material which is too hard in comparison with the material of the spinnerets in order to avoid damaging the spinnerets with the cleaning blades. Good results have been obtained, for example, with cleaning blades made of brass, bronze, grey cast iron or aluminium.

Very good results are obtained if the cleaning blades are treated prior to use with an agent to reduce the surface adhesion. Examples of such an agent are polytetrafluoroethylene (sold under the Registered Trade Mark Teflon), and silicon. The cleaning plate can therefore be dispensed with in many cases, particularly when spinning polyamide-6.

In the accompanying drawings: Figure 1 shows a section along the line I-I through the embodiment illustrated in simplified form in Figure 2 of the apparatus according to the invention with two cleaning blades and a fourhole spinneret; Figure 2 shows a section through Figure 1 along the line Il-Il; Figure 3 shows a section through a circular cleaning blade of the apparatus according to the invention and a spinneret with a circular arrangement of holes; Figure 4 shows a spinneret with holes in which the holes are arranged in two circular arrays on different diameter; Figure 5 shows a section through two circular cleaning blades of the apparatus according to the invention which are arranged on a common base plate and are suitable for cleaning spinnerets according to Figure 4;; Figure 6 shows a spinneret with holes arranged in seven rows; Figure 7 shows a section through seven cleaning blades of the apparatus according to the invention which are arranged in a straight line on a common base plate and are suitable for cleaning spinnerets according to Figure 6; Figure 8 shows a section through an embodiment illustrated in simplified form, with five straight cleaning blades arranged on a common base plate and a grid-type plate provided for protecting and cleaning it along line VIll-VIll in Figure 9; Figure 9 shows a section through Figure 8 along line IX-IX; Figure 10 shows a section through an embodiment, illustrated in simplified form, in which the pressing force is adjustable between the cleaning blade or blades and the spinneret;; Figure 11 shows an embodiment with a movable motor and flexible driving shaft for the cleaning blades; and Figures 12 and 13 show a circular base plate, with which the cleaning blades are arranged to run radially.

The spinneret 1 illustrated in Figures 1 and 2 has four spinneret holes 2 through which a spinning composition is extruded and shaped into filaments. The four openings 2 are arranged in two rows of holes each having two openings 2.

Two straight cleaning blades 3 which are joined together by a cross member 4 are used cleaning the four holes 2. On this cross member 4 is arranged a guide 5 in which an eccentric pin 6 of the rotatably arranged driving shaft 7 engages, the eccentric pin 6 being freely rotatable in the guide 5. The eccentric pin 6 moves over a circular path 8 as the shaft 7 rotates. The non-frictional connection beween eccentric pin 6 and guide 5 causes the cleaning blades 3 and the connecting cross member 4 also to move over a circular path so that each point of the cleaning blades 3 and the cross member 4 describes a circular path of the same size as the eccentric pin 6. The cleaning blades 3 pass over the two spinneret openings 2 allocated to each of them twice during each rotation of the shaft 7.In order to prevent the connecting cross member 4 from rotating with the cleaning blades 3 which are arranged thereon about the central axis of the guide 5, it may be advantageous to provide means to prevent such rotation. Such means are known and are not illustrated in Figures 1 and 2.

In the spinneret 1 illustrated in Figure 3, the spinneret holes 2 are arranged in a common circular array of holes. The holes 2 are thus all equidistant from the centre 9 of the circular array of holes. A circular cleaning blade 3 arranged on a base plate 10 is used for cleaning the holes 2 of this spinneret 1. The cleaning blade 3 has the same external diameter in this arrangement as the base plate 10. The base plate 10 with the cleaning blade 3 arranged on it is driven in the same manner as the embodiment illustrated in Figures 1 and 2, the eccentric pin of the drive shaft engaging in a centre 11 of the base plate 10. The centre 11 of the base plate 10 thus moves over the circular path 8 about the centre 9 of the circular array of holes of the spinneret 1 as the driving shaft is rotated.All the points on the base plate 10 and the cleaning blade 3 which are preferably secured against rotation about their centre 11 also describe a circular path of the same size as the centre 11 of the base plate 10.

The circular cleaning blade 3 therefore passes over each spinneret hole 2 a total of two times during each rotation of the shaft, each from substantially the opposite direction.

Figure 4 shows a spinneret 1 in which the spinneret holes 2 are arranged on two concentric circular arrays of holes of different diameter. The cleaning blades 3, for example, which are illustrated in Figure 5 and are arranged on a common base plate 10 are suitable for cleaning a spinneret of this type. In this embodiment, the base plate 10 has the same diameter as the outermost of the two cleaning blades 3. The twd cleaning blades 3 are also arranged concentrically on the base plate 10 to correspond to the arrangement of the spinneret holes 2 of the spinneret in Figure 4 and have an average diameter which is equal to the diameter of the respective circular array of holes 2.To clean the spinneret 1, the base plate 10 and, with it, the two cleaning blades 3 perform a circling movement, the centre 11 of the base plate 10 moving over the circular path 8 illustrated in Figure 4. The base plate 10 does not rotate about its centre 11 in this arrangement.

With the spinneret 1 illustrated in Figure 6, the spinneret openings 2 are arranged in seven rows of holes parallel to each other. The seven straight cleaning blades 3 which are illustrated in Figure 7 and are arranged on a common round base plate 10 are used for cleaning a spinneret of this type.

The distance between the seven cleaning blades 3 corresponds to the distance between the seven rows of holes in the spinneret 1 illustrated in Figure 6. The cleaning blades 3 illustrated in Figure 7 and arranged on a common base plate 10 can perform a circling movement in order to clean the spinneret illustrated in Figure 6, as already described in more detail in the description of the embodiments illustrated in Figures 1 to 5, or can perform a simple to and fro movement in which the centre 11 of the base plate 10 is moved, for example, over a rectilinear path of movement 12, as illustrated in Figure 6, all points on the common base plate 10 as well as the cleaning blades 3 then also performing a simple translatory movement with the same path lengths as the centre 11.

The embodiment of the apparatus according to the invention illustrated in Figures 8 and 9 has five straight cleaning blades 3 which are arranged on a common base plate 10 which can be shifted in a circling movement by the eccentric pin 6 of the driving shaft 7 as well as a grid-type plate 1 3 which serves to protect and to clean the cleaning blades 3. This embodiment also has a stop-plate 14 with four fixing pins 1 5 which engage in corresponding recesses 1 6 in a spinning machine cover 1 7. In this way, the position of the apparatus according to the invention is determined precisely relative to the spinneret openings 2 of the spinneret 1.

When the apparatus is in the rest position, lower compression springs 1 8 are almost completely relaxed so that a catch ring 1 9 rests on the head pieces 21- of the two guide bolts 20.

A radial bearing 22 is provided between the catch ring 1 9 and the driving shaft 7 in order to prevent the rotation of the driving shaft 7 from being transferred to the catch ring 1 9. Upper compression springs 23 are also almost completely compressed in the rest position of the apparatus so that the upper narrow side 24 of the cleaning blades 3 is located in slits 25 in the grid like plate 1 3. The driving shaft 7 of the apparatus according to the invention which has been brought into position by the engagement of the fixing pins 1 5 in the recesses 1 6 is moved in the direction of the arrow 34, i.e. towards the spinneret 1, in order to clean the holes 2 arranged in five rows in the spinneret 1.This compresses the lower compression springs 14 while the upper compression springs 23 simultaneously relax.

This causes the cleaning blades 3 to leave the slits 25 of the grid-like plate 13 until the grid-like plate 13 rests on the base plate 10. As the shaft 7 continues to move in the direction of the arrow 34, the grid-like plate 13 is raised so that guide pins 26 which are rigidly connected to it are also raised so that they do not touch the stationary i stop plate 14 during the circling movement of the base plate 1 b, the cleaning blades and the grid like plate 1 3 which takes place when the spinneret 1 is being cleaned. Once the spinneret 1 has been cleaned, the apparatus automatically ) returns into its rest position under the force exerted by the lower compression springs 1 8 as they are relaxed.

Figure 10 shows an apparatus according to the invention with a round cleaning blade 3 arranged 5 on a base plate 10 for cleaning a circular array of spinneret holes of a spinneret 1, arranged in the operating position. This embodiment has a housing 27 and a stop plate 14 which is rigidly fixed to the housing with fixing pins 1 5 whose mode of operation has already been described in detail in the description qf the embodiment illustrated in Figures 8 and 9. In order to clean the spinneret, a handle 28 is firstly moved in the direction of the arrow 38, i.e. towards the spinneret 1, until it touches a stop 29 of the housing 27.The forward movement of the handle 28 causes the driving shaft 7 and, with it, the base plate 10 as well as the cleaning blade 3 also to be moved via a spacer ring 30, an adjusting ring 31, a lower compression spring 18, and axial bearing 32 and a shaft collar 33 toward the spinneret 1 until the cleaning blade 3 touches the spinneret 1. In this embodiment, the force with which the cleaning blade 3 is pressed against the spinneret 1 is independent of the force with which the handle is pressed upwards since the pressing force is only based on the force which is applied by the lower compression spring 18. This in turn can be adjusted by suitable dimensioning of the spacer ring 30 with corresponding dimensioning of the lower compression springs 1 8 and the upper compression springs 23 to any desired value.The upper compression springs acting via the catch ring 1 9 and the radial bearing 22 on the driving shaft 7 cause the apparatus to return automatically into its rest position after use and once the handle 28 has been released.

In the embodiment of the apparatus according to the invention illustrated in Figure 11, the cleaning blades arranged in the housing 27 are driven by a motor 36 by means of the flexible driving shaft 35. An upper portion 44 of the housing 27 is frusto-conical and therefore adapted to the frusto-conical recess 1 6 present in the spinning machine cover 1 7 beneath the spinneret 1. The housing 27 with the cleaning blades and the other devices illustrated in Figures 1 to 10 hangs in a mounting 37. A fan 38 serves to cool the cleaning blades and supplies the cooling air to the cleaning blades via a pipe 39.

The drive motor 36 for the cleaning blades and the motor for the cooling fan 38 are connected to an electric battery 40 and switched on and off by means of switches 41. All devices in this embodiment are arranged on a frame 43 which can be moved on rollers 42. In order to clean a spinneret, the operator takes the movable part of the apparatus which is connected to the motor 36 via the flexible driving shaft 35 on the handle 28 from the mounting 37, guides its upper frustoconical part 44 into the frusto-conical recess 1 6 and presses the cleaning blades against the surface of the spinneret with the aid of the handle 28, as already described above.

Upon completion of the cleaning process, the upper part of the apparatus is again suspended in the mounting 37, whereupon the cleaning blades are cooled by the air stream brought via the pipe 39 by the fan 38. In order to avoid loading the electric battery unnecessarily, it has proven advantageous to use a circuit of the type illustrated in Figure 11.In this circuit, the electric motor 36 is only switched on, for example by means of a proximity switch fitted in the movable part of the apparatus, immediately before the cleaning blades touch the surface of the spinneret or after the optimum pressing force for cleaning the spinneret has been attained, and is switched off again immediately after the release, and the cooling fan 38 only remains connected, for example by means of a suitable limit switch as long at the movable part of the apparatus is suspended in the mounting 37 or as long as is absolutely necessary to cool the cleaning blades.

The use of a proximity switch in conjunction with a time relay, for example, allows a previously adjustable cleaning period which remains constant for each spinneret.

Example 1 An apparatus according to the invention with a grid-like cleaning and protecting plate according to Figures 8 and 9 and an adjustable pressing force according to Figure 10 has been used successfully to clean spinnerets used for spinning polyester and bi-component filaments and having an external diameter of 85 mm. The spinnerets each had 72 spinneret holes with a diameter of 350 or 500 microns which were arranged in 1 5 rows in the form of a honeycomb. The apparatus consequently had 1 5 cleaning blades which were 1 mm wide. The drive motor was connected via a rigid shaft to a common base plate for the cleaning blades.

The apparatus weighted approximately 7.3 kg.

The throughput per nozzle was approximately 3.0 and 3.55 g/s. Cleaning blades made of MS 63 F 38bK, MS 60, GG25, GSBZ and AIF32 were used successfully.

Example 2 An apparatus according to Figure 11 with the device according to Figures 8 to 10 was used successfully for cleaning spinnerets with 10 spinneret holes arranged in a circular array for the spinning of polyamide6 filaments of the 40 f 10 type. The apparatus had a round cleaning blade.

The pressing force between the cleaning blade and spinneret was approximately 20 N. The flexible drive shaft for driving the cleaning blades rotated at about 3.7 revolutions per second.

Example 3 Excellent results have been achieved with an embodiment of the apparatus according to the invention in which the cleaning blades are arranged to run radially on a round base plate, as illustrated in Figure 12. The cleaning blades were cooled in this arrangement with the aid of a cooling block consisting of several Peltier elements. The temperature of the cleaning blades could be kept at an extremely low temperature level by means of this device. This rendered it unnecessary to use a plate, such as the plate 1 3 illustrated in Figures 8 and 9, since the cleaning blades did not become caked with melt owing to the low temperature at which the cleaning blades could be kept with the aid of the Peltier cooling block. This low temperature level could also be maintained when a larger number of spinnerets was cleaned in succession.

An embodiment according to Figure 13, in which a different number of cleaning blades was arranged in two circular arrays was used successfully for cleaning spinnerets with several circular arrays of holes and a different number of holes in each circular array.

With both embodiments, the temperature of the cleaning blades never rose above 1 000C during the cleaning of a spinneret and always fell to 400C between two cleaning processes. in the embodiment with air cooling, the corresponding temperatures were approximately 1 800C and approximately 1450C, i.e. a reduction in the total temperature level of the cleaning blades of 80 to 1 050C was achieved with the Peltier cooling block.

The remaining conditions correspond to those described in Example 1 or 2.

The cooling of the cleaning blades was particularly good when the cleaning blades were brought into contact with a flat plate between two spinneret cleaning processes, the fiat plate having been kept constantly at a lower temperature by a Peltier cooling block.

Claims

1. An apparatus for cleaning spinnerets fitted in spinning machines in the operating condition, the apparatus comprising at least one cleaning blade which is movable in a plane parallel to the surface of the spinneret and having one side running parallel to the surface of the spinneret in contact therewith, wherein the said side of the or each cleaning blade is in the form of a planar face, the or each cleaning blade is arranged to be pressed against the surface of the spinneret with an adjustable force, the apparatus has positively acting guide means, and the cleaning blade or blades is or are movably arranged with all their points on tracks of similar shape and similar path lengths.

2. An apparatus according to claim 1, wherein the arrangement, number and shape of the cleaning blades are adapted to the number and arrangement of the spinneret holes of the spinneret to be cleaned.

3. An apparatus according to claim 1 or 2, wherein there is a plurality of straight cleaning blades which are arranged parallel and at distances to one another.

4. An apparatus according to claim 1 or 2, wherein there is a plurality of circular cleaning blades which are arranged concentrically at distances from each other.

5. An apparatus according to any one of claims 1 to 3, wherein the or each cleaning blade is arranged so that it can move to and fro in a direction running perpendicularly to its longitudinal direction.

6. An apparatus according to any preceding claim, wherein the or each cleaning blade is arranged to be moved by means of a crank or eccentric pin of a rotatably arranged shaft.

7. An apparatus according to any preceding claim, wherein a movable motor connected to the cleaning blade or blades only by a flexible driving shaft is provided for driving the cleaning blade or blades.

8. An apparatus according to any preceding claim, wherein a device is provided for cooling the cleaning blade or blades.

9. An apparatus according to claim 8, wherein at least one Peltier cooling element is provided for cooling the cleaning blade or blades.

10. An apparatus according to any preceding claim, wherein a protecting and cleaning device is provided for the cleaning blade or blades.

11. An apparatus for cleaning spinnerets, substantially as herein described with reference to any one of the embodiment shown in the accompanying drawings.