AT522178B1 - Plasticizing device for a molding machine - Google Patents

Abstract

Plasticizing device (1) for a molding machine (2), in particular for an injection molding machine or transfer press, with a plasticizing cylinder (3), a plasticizing screw arranged in the plasticizing cylinder (3), rotatable about a longitudinal axis (L) and linearly movable along the longitudinal axis (L) (4), the plasticizing screw (4) having at least one functional area (5), a sensor (6) arranged in or on the plasticizing cylinder (3), with which the distance (D) to the surface of the at least one functional area (5) of the plasticizing screw (4) is measurable, and a detection device (7) for detecting the type (T) of the functional area (5) and / or the operating state (B) of the functional area (5), which is configured to do so by moving the functional area (5 ) to record a distance signal curve (V) relative to the distance sensor (6), to compare the recorded distance signal curve (Vist) with a stored distance signal curve (Vref) and to output a signal (ST, SB) representing the type (T) of the functional area (5) and / or the operating state (B) of the functional area (5) as a function of a match between the detected distance signal profile (Vist) and a stored distance signal profile (Vref).

Description

description

The invention relates to a plasticizing device, a molding machine, in particular for an injection molding machine or transfer press, with a plasticizing cylinder, a plasticizing screw arranged in the plasticizing cylinder, rotatable about a longitudinal axis and linearly movable along the longitudinal axis, the plasticizing screw having at least one functional area, and one in or a sensor arranged on the plasticizing cylinder, with which the distance to the surface of the at least one functional area of the plasticizing screw can be measured. The invention also relates to a shaping machine with such a plasticizing device and a method for operating a plasticizing device.

In the shaping process, different functional areas are used depending on the requirements. Functional areas can be, for example, a non-return valve, a screw flight zone of the plasticizing screw, a mixing head or a mixer. Depending on the type of functional area used, certain processing parameter limits or recommendations must be observed. The disadvantage is that the functional area is no longer visible to the operator after installation.

[0003] DE 10 2011 103 810 A1 discloses a plasticizing unit with a wear sensor. A signal is output via an evaluation unit as soon as the distance between the plasticizing cylinder and plasticizing screw measured by a measuring sensor has reached a definable limit value. A wear curve can also be displayed. With this system, conclusions can only be drawn about the wear and tear of the plasticizing screw without having a direct view of the inside of the plasticizing cylinder.

The object of the present invention is therefore to create a plasticizing device which is improved over the prior art. In particular, the known disadvantages should be avoided. Above all, a possibility for a better analysis should be created without having to remove the plasticizing screw.

This is achieved by a plasticizing device having the features of claim 1. Accordingly, according to the invention, a detection device for detecting the type of functional area and / or the operating state of the functional area is provided, which is configured to detect a distance signal profile by moving the functional area relative to the distance sensor, to compare the detected distance signal profile with a stored distance signal profile and as a function to output a signal representing the type of the functional area and / or the operating state of the functional area if the detected distance signal profile matches a stored distance signal profile. This enables the built-in functional area of the plasticizing screw to be identified independently without having to remove the plasticizing screw.

Preferred exemplary embodiments are specified in the dependent claims.

As functional areas, all those areas of a plasticizing screw or a non-visible part located in the plasticizing cylinder can be referred to that fulfill a specific function during the plasticizing and injection process. Specifically, a non-return valve, a screw flight zone of the plasticizing screw or a mixer form such a functional area. The functional area can also be referred to as a component for performing a work step.

[0008] The distance signal course can in itself represent the course of the distance from the (distance) sensor to any section and to any component of the functional area. It is preferably provided that the distance signal curve represents the surface contour of the functional area. This means that the surface of the functional area is scanned and a distance signal profile is created from it. The (recorded) form of the functional area itself thus gives rise to the type of the functional area. The surface contour thus serves as a type identification means.

Alternatively (or additionally) it can be provided that as identification means to the He

know the type of functional area a surface code formed in the functional area functions. Specifically, this surface code can be formed by additional introduced or applied, (procedurally optimized) protruding or deepening geometric elements. For example, reference should be made to grooves, webs, bores and similar built-in components for the purpose of serial or component identification. For example, a (geometric) surface code can also be lasered into the plasticizing screw, preferably in its functional area.

It can be determined with the detection device not only the type, but alternatively or additionally the operating state of the functional area. An operating state can be, for example, the switch position of the functional area. With reference to the functional area in the form of a non-return valve, for example, a distinction can be made between the switch position “closed” and “open”. On the basis of the distance signal curve, it can therefore be concluded whether the non-return valve is currently open or closed and a corresponding signal can be output. The movements of the locking ring or the oscillation (orbital movement) of the tip can also be recorded in order to identify the operating status of the plasticizing screw. If the process parameters are not optimally set, the plasticizing screw oscillates or the lock in the cylinder.

It is also possible that the detection device is used to measure, for example, the wear on the non-return valve (e.g. shortening of the tip wings) or the length of the locking ring. The number of balls used in the non-return valve can also be determined.

The identification of the type or the operating state does not have to take place in every cycle. The detection device can be configured, for example, in such a way that the type of functional area and / or the operating state of the functional area is detected only after a machine stop or after a standstill that lasts longer than a predetermined time.

From the determined type of functional area and / or operating state, a specification or recommendation of processing parameters for the optimal service life and for safe operation can be derived. If a certain type or operating status is determined, this is compared with the set processing parameters. If there is a discrepancy here, a warning signal can be output or the processing parameters can be (automatically) changed or adapted. Possible processing parameters and their limitations are speed, temperature of the temperature control device, temperature profile, compression relief, dosing stroke (shot weight), ramps and the validation / suitability of the installed components with regard to the suitable plastics.

[0014] The recorded data enable operating data to be recorded. In particular, this can be used to calculate a collective load (accumulated load). In this way it can be calculated how long a non-return valve has produced with different parameters. This also enables preventive maintenance: when a certain working time has been reached, maintenance can be carried out again. This allows the maintenance intervals to be controlled. Above all, there are variable maintenance intervals that are adapted to actual consumption.

According to a preferred embodiment it is provided that the stored distance signal curve is stored in a memory of the plasticizing device or can be called up from a cloud via a data line.

Furthermore, it is preferably provided that the detection of the distance signal curve takes place when the plasticizing screw rotates (around the longitudinal axis), when the plasticizing screw is linearly movable along the longitudinal axis or when the plasticizing screw rotates and translationally (along the longitudinal axis).

The stored distance signal profile can be based on a distance signal profile specified for the functional area. This means that when the plasticizing screw is installed, a reference distance signal matching the functional area or areas is generated.

history deposited. This can be provided by the manufacturer of the plasticizing screw. Alternatively, it is possible that a one-time detection run is carried out after the plasticizing screw has been installed. A distance signal curve (graph) is recorded and saved in order to enable a comparison later. Again, alternatively, functional area-specific courses can be recorded and compared with a defined speed and a defined movement.

[0018] The following components or areas can form specific functional areas:

- In the case of a functional area in the form of a non-return valve, the type of functional area is a ball lock, a wing lock, a link lock, a multi-ball lock or a ring non-return valve.

- In the case of a functional area in the form of a spiral flight, the type of functional area is a single-flight screw, a barrier screw, a double-flight screw, a metering zone, a compression zone or a feed zone.

- In the case of a functional area in the form of a mixer, the type of functional area is a toothed disk mixer, a diamond mixer, a shear mixer head, a shear part, a spiral shear part or a Maddock mixer.

The measurement of the distance can be carried out with any suitable sensor. It is preferably provided that the sensor is designed as a sound sensor (preferably as an ultrasonic sensor), as an electromagnetic sensor or as a capacitive sensor.

[0020] Furthermore, it is preferably provided that the sensor has at least one measuring head. At least two measuring heads spaced from one another along the longitudinal axis or along the circumference are particularly preferably provided.

[0021] The at least one measuring head can be located in the interior of the plasticizing cylinder. It can also be arranged at a distance from the plasticizing cylinder. However, it is preferably provided that the at least one measuring head is arranged on the plasticizing cylinder, preferably on the outside of the plasticizing cylinder, particularly preferably in a blind bore formed on the outside of the plasticizing cylinder. Even if two measuring heads are provided, they can each be arranged in a blind hole.

A control or regulating unit for controlling or regulating movements of the plasticizing screw is preferably provided. This control or regulation unit preferably has a display device, preferably a screen, and an input device, preferably in the form of a keyboard. The control or regulation unit can be part of a higher-level machine control system for the entire molding machine.

The recognition device can be designed as part of the control or regulation unit. Alternatively, the detection device can be in signaling connection with the control or regulation unit.

Protection is also sought after for a molding machine with a plasticizing device according to the invention.

The object described above is also achieved by a method having the features of claim 15. Accordingly, the invention provides that the type of functional area and / or the operating state of the functional area is recognized by the steps of moving the functional area relative to the distance sensor, acquiring a distance signal curve, comparing the recorded distance signal curve with a stored distance signal curve and outputting the type of the functional area and / or the signal representing the operating state of the functional area as a function of a match between the detected distance signal profile and a stored distance signal profile.

Further details and advantages of the present invention are explained in more detail below on the basis of the description of the figures with reference to the exemplary embodiments shown in the drawings. Show in it:

1 shows a schematic side view of a molding machine with a plasticizing device,

2-3 sections through the plasticizing cylinder with different positions of the plasticizing screw along the longitudinal axis,

5 + 6 radial cross-sections through the plasticizing cylinder with different rotary positions of the plasticizing screw,

7 shows a diagram with an exemplary distance signal curve,

8 shows a schematic section through a plasticizing cylinder and a plasticizing screw,

FIG. 9 shows a diagram with a distance signal curve matching FIG. 8,

10a-10c different representations of a non-return valve in the form of a single ball lock,

11a-11c various representations of a non-return valve in the form of a central ball lock,

12a + 12b different representations of a non-return valve in the form of a multi-vane barrier,

FIG. 13 shows a cross section corresponding to FIGS. 10a to 10c,

FIG. 14 shows a cross section corresponding to FIGS. 11a to 11c,

15 shows a cross section corresponding to FIGS. 12a and 12b

[0039] FIG. 16a shows a front view corresponding to FIG. 10c,

[0040] FIG. 16b shows a diagram with a distance signal profile matching FIG. 16a, FIG. 17a shows a front view matching FIG. 11c,

[0042] FIG. 17b shows a diagram with a distance signal curve matching FIG. 17a, [0043] FIG. 18a a front view matching FIG. 12c and FIG

FIG. 18b shows a diagram with a distance signal curve matching FIG. 18a.

In Fig. 1, a molding machine 2 is shown in a schematic side view. This shaping machine 2 has a clamping unit 11 (shown on the left). This clamping unit 11 comprises a movable platen 12, a stationary platen 13, a mold 14 mounted on the platen 12 and 13 and a drive device 15 (for example in the form of a toggle system) for the movable platen 12. In the closed mold 14 there is at least one cavity K trained.

The molding machine 2 has a plasticizing device 1 (shown on the right). This plasticizing device 1 comprises a plasticizing cylinder 3 and a plasticizing screw 4 arranged in the plasticizing cylinder 3, rotatable about a longitudinal axis L and linearly movable along the longitudinal axis L. The plasticizing screw 4 is driven by a drive device 16, for example an electric motor. Via the filling funnel 18, for example, granular plastic is filled into the plasticizing cylinder 3 and melted there. Melted plastic is injected into the Kim mold cavity 14 via the injection channel 19. The injected plastic then hardens in the cavity K to form at least one shaping part (injection molded part).

The plasticizing screw 4 has at least one functional area 5. In Fig. 5 three exemplary functional areas 5 are shown - a non-return valve 5a, a mixer 5b and a screw flight zone 5c. A measuring head 6a of a sensor 6 is assigned to each of these functional areas 5. Together with an evaluation unit 6b, each measuring head 6a forms a transmitter

sor 6.

The plasticizing device 2 has a detection device 7 for detecting the type T of the functional area and / or the operating state B of the functional area 5. By moving the functional area 5 relative to the sensor 6, a distance signal curve V is recorded by the sensor 6. Specifically, the measuring head 6a of the sensor 6 records the distance D to the surface of the functional area 5. During the movement of the plasticizing screw 4 relative to the plasticizing cylinder 3, a new value of the distance D is recorded at regular time intervals (e.g. in the millisecond range). The entire recorded measured values of the distance D result in a recorded distance signal profile Vis. This detected distance signal profile Visı is compared with at least one (preferably in a memory 8) stored distance signal profile Vrer. Depending on whether the detected distance signal profile Vis matches a stored distance signal profile Ver, a signal St or Se representing the type T of the functional area 5 and / or the operating state B of the functional area 5 is output.

The plasticizing device 1 has a control or regulating unit 10. The detection device 7 is in signaling connection with this control or regulation unit 10. The signal St or Ss representing the type T or the operating state B is preferably transmitted to this control or regulating unit 10. The type T or operating state B of the checked functional area 5 recognized by the recognition device 7 can be displayed via the screen 17. The recognized type T or recognized operating state B does not have to be displayed, but the corresponding signal can be taken into account or used in the control or regulation of the movement of the plasticizing screw 4. The operating state B can represent two switching states of the functional area 5, for example. Specifically, the operating state B can represent the switching state (“closed” or “open”) of the locking ring 20 of the non-return valve 5a.

2 shows a section through a plasticizing cylinder 3 with a plasticizing screw 4. The plasticizing cylinder 3 has a flange 21. Blind bores 9 are formed on the inside of the plasticizing cylinder 3. A measuring head 6a of a sensor 6 is arranged in each of these blind bores 9. The functional area 5 is designed as a non-return valve 5a. The non-return valve 5a has the locking ring 20, the stop 22 (in this case a pressure ring) and several balls 23 (in this case bearing balls). The plasticizing screw 4 is currently moving forward, which is indicated by the movement arrow P. At the same time, there is also a rotary movement about the axis of rotation of the plasticizing screw 3 (see movement arrow R). The measuring head 6a determines the distance D at time t +; detected.

In Fig. 3 a section is shown again through the same plasticizing cylinder 3, the plasticizing screw 4 has already moved further forward. In this case, no second measuring head 6a is shown. The measuring head 6a arranged in the plasticizing cylinder 3 detects the distance D between the surface of the functional area 5 at time t ».

In the same way, according to FIG. 4, the distance D between the surface of the functional area 5 is detected at the time ts. With the position according to FIG. 4, the forward movement of the plasticizing screw 4 is completed. But there is still another rotary movement.

5 shows a radial cross section through the plasticizing cylinder 3 including the plasticizing screw 4. The balls 23 of the non-return valve 5a can be seen, which are arranged at regular intervals from one another around the plasticizing screw 4. The measuring head 6a measures the distance D to the surface (specifically to the locking ball 23) of the functional area 5 at the point in time ta.

According to FIG. 6, the plasticizing screw 4 has rotated further through the angle W. As a result, the distance D between the measuring head 6a and the functional area 5 has increased. This distance D corresponds to the point in time ts.

The detected distances D at the times t +; to ts are combined into a distance signal curve V by the detection device 7. An exemplary spacing signal

signal curve V is illustrated in the diagram according to FIG. The ordinate of this diagram shows the distance D detected by the sensor 6. The abscissa of this diagram shows the time t. The distances D at the various times t; to ts specified. This distance signal profile V can correspond to a detected distance signal profile Viss or a stored distance signal profile Ve :.

In other words, FIGS. 2 to 7 can be described as follows: When the plasticizing screw 4 moves forwards or backwards, a measuring range of a sensor 6 is swept over. The sensor 6 can be mounted in the flange 21 or in the plasticizing cylinder 3. The sensor 6 can be designed as an ultrasonic sensor. During the axial movement, the distances D to the contour of the screw tip and the associated components are measured and recorded. The signal obtained corresponds to the distance D to a reflection surface or topography on one or more components of the plasticizing screw 4 (e.g. non-return valve 5a or mixing parts). During the movement, the distance signal curve V results as a function of time t, the position along the longitudinal axis L and the angle W, which is normalized with the speed. Depending on the basic shape of the functional area 5, a characteristic curve results which can be clearly assigned to the type T of the functional area 5. To compare the characteristic distance signal curves V, these are set in relation to the position during the time curve and the speed, and the graphs obtained in this way are compared by superimposing them.

In Fig. 8 is a schematic section through a plasticizing cylinder 3 and a plasticizing screw 4 is shown. The plasticizing screw 4 has a functional area 5 in the form of a screw flight zone 5c. This screw flight zone 5c has one or more screw flights 24 which are wound helically around the plasticizing screw 4.

When the plasticizing screw 4 moves according to FIG. 8 in the direction of the movement arrow P and / or when the plasticizing screw 4 rotates about the longitudinal axis L, a distance signal profile Vis is detected by the sensor 6. This is illustrated in FIG. 9. The elevations in the distance signal curve Viss correspond to the groove-shaped screw flights 24, since there the distance D to the sensor 6 is greater than in the area of the screw flights 25. The recorded distance signal curve Vi «results in a characteristic signal which is compared with the stored distance signal curves V, e :. The recognized type T of the functional area 5 is output as a function of a match. Stored distance signal curves Ver can be stored digitally in a kind of library.

10a, 10b and 10c show different representations of a non-return valve 5a. FIG. 10a shows a side view, FIG. 10b shows a cross section and FIG. 10c shows a front view. In this case, the non-return valve 5a is designed as a so-called single-ball lock with a single (locking) ball 23 and a locking ring 20.

In contrast, FIGS. 11a (side view), 11b (cross section) and 11c (front view) show a non-return valve 5a in the form of a central ball lock. Here the ball 23 together with the ball seat forms a ball valve. In the area of the screw tip 27, this non-return valve 5 a has a plurality of outflow openings 26 which are regularly arranged around the longitudinal axis L.

12a (cross section) and 12b (front view) show a ring non-return valve 5a in the form of a multi-vane barrier. In this case, the multi-vane lock has three vanes 28 which are arranged around the longitudinal axis L and are regularly spaced from one another.

13 shows a non-return valve 5a according to FIG. 10b, which is arranged in a plasticizing cylinder 3.

14 shows a non-return valve 5a according to FIG. 11b, which is arranged in a plasticizing cylinder 3 with a measuring head 6a.

15 shows a non-return valve 5a arranged in the plasticizing cylinder 3 according to FIG. 12a.

16a shows the front view according to 10c and schematically of the measuring head 6a. While

When the plasticizing screw 4 rotates, the measuring head 6a scans the functional area 5 - in this case the surface of the non-return valve 5a designed as a central ball lock. This results in the characteristic distance signal profile Viss according to FIG. 16b. The increases in the distance signal profile Vis correspond to the lateral flattened areas 29 on the non-return valve 5a.

In contrast, FIG. 17a shows the front view according to FIG. 11c. By scanning the surface with the measuring head 6a (as indicated in FIG. 14), the distance signal profile Vis results: according to FIG. 17b. The regularly arranged elevations in which the distance D is greater and which correspond to the individual outflow openings 28 in the screw tip 27 are clearly visible.

FIG. 18a shows the front view according to FIG. 12b of a non-return valve 5a in the form of a multi-vane barrier. In the recorded distance signal profile Vis shown in FIG. 18b, the elevations correspond to the notches between the blades 28 of the screw tip 27.

REFERENCE CHARACTERISTICS LIST:

1 plasticizing device

2 forming machine 3 plasticizing cylinder

4 plasticizing screw

5 functional area

5a non-return valve

5b mixer

5c screw flight zone

6 sensor

6a measuring head

6b evaluation unit

7 detection device

8 memories

9 blind hole

10 control or regulation unit

11 clamping unit

12 movable platen

13 fixed platen

14 Form tool

15 Drive device for movable platen 16 Drive device for plasticizing screw 17 Screen

18 funnel

19 injection port

20 locking ring

21 flange

22 stop

23 balls (locking ball or bearing balls) 24 worm flights

25 screw flights

26 outlets

27 snail tip

28 blades

29 side flats

L longitudinal axis

D distance

T Type of functional area

B Operating state of the functional area V Distance signal curve

Vist detected distance waveform

Four deposited distance signal curve

St type representing signal

Se operating state representing signal P movement arrow

R movement arrow

W angle

Claims (15)

Claims 1. Plasticizing device (1) for a molding machine (2), in particular for an injection molding machine or transfer press, with - a plasticizing cylinder (3), - A plasticizing screw (4) arranged in the plasticizing cylinder (3), rotatable about a longitudinal axis (L) and linearly movable along the longitudinal axis (L), the plasticizing screw (4) having at least one functional area (5), and - A sensor (6) arranged in or on the plasticizing cylinder (3), with which the distance (D) to the surface of the at least one functional area (5) of the plasticizing screw (4) can be measured, marked by - A recognition device (7) for recognizing the type (T) of the functional area (5) and / or the operating state (B) of the functional area (5), which is configured by moving the functional area (5) relative to the distance sensor (6 ) to record a distance signal course (V), to compare the recorded distance signal course (Vie) with a stored distance signal course (Vrer) and, depending on whether the recorded distance signal course (Visı) matches a stored distance signal course (Vrer), enter the type (T) of the functional area (5) and / or the operating state (B) of the functional area (5) representing signal (ST, Se) output. 2, plasticizing device according to claim 1, characterized in that the functional area (5) is a non-return valve (5a), a screw flight zone (5c) of the plasticizing screw (4) or a mixer (5b). 3. Plasticizing device according to claim 1 or 2, characterized in that the distance signal curve (V) represents the surface contour of the functional area (5). 4. Plasticizing device according to claim 3, characterized in that a surface code formed in the functional area (5) acts as an identification means for recognizing the type (T) of the functional area (5). 5. Plasticizing device according to one of claims 1 to 4, characterized in that the detection of the distance signal curve (V) when the plasticizing screw (4) is rotating, when the plasticizing screw (4) is linearly movable along the longitudinal axis (L) or when the plasticizing screw is rotating and translationally movable (4) takes place. 6. Plasticizing device according to one of claims 1 to 5, characterized in that the stored distance signal curve (V, er) is stored in a memory (8) of the plasticizing device (1) or can be called up from a cloud via a data line. 7. Plasticizing device according to one of claims 1 to 6, characterized in that - in the case of a functional area (5) in the form of a non-return valve (5a), the type (T) of the functional area (5) is a ball lock, a wing lock, a link lock, a multi-ball lock or a ring non-return valve, - In the case of a functional area (5) in the form of a screw flight zone (5c), the type of functional area (5) is a single-flight screw, a barrier screw, a double-flight screw, a metering zone, a compression zone or a feed zone, - In the case of a functional area (5) in the form of a mixer (5b), the type of functional area (5) is a toothed disk mixer, a diamond mixer, a shear mixing head, a shear part, a spiral shear part or a Maddock mixer. 8. Plasticizing device according to one of claims 1 to 7, characterized in that the sensor (6) is designed as a sound sensor, preferably as an ultrasonic sensor, as an electromagnetic sensor or as a capacitive sensor. 9. Plasticizing device according to one of claims 1 to 8, characterized in that the sensor (6) has at least one measuring head (6a), preferably at least two, along the longitudinal axis (L) or along the circumference spaced apart measuring heads (6a). 10. Plasticizing device according to claim 9, characterized in that the distance sensor (6) has an evaluation unit (6b) connected to the measuring head (6a). 11. Plasticizing device according to claim 9 or 10, characterized in that the at least one measuring head (6a) on the plasticizing cylinder (3), preferably on the outside of the plasticizing cylinder (3), particularly preferably in a blind hole formed on the outside of the plasticizing cylinder (3) (9), is arranged. 12. Plasticizing device according to one of claims 1 to 11, characterized by a control or regulating unit (10) for controlling or regulating movements of the plasticizing screw (4). 13. Plasticizing device according to claim 12, characterized in that the detection device (7) forms part of the control or regulating unit (10) or is in signaling connection with the control or regulating unit (10). 14. Molding machine (2) with a plasticizing device (1) according to one of claims 1 to 13. 15. A method for operating a plasticizing device (1) of a shaping machine (2), in particular an injection molding machine or transfer press, the plasticizing device (2) having a plasticizing cylinder (3), - A plasticizing screw (4) arranged in the plasticizing cylinder (3), rotatable about a longitudinal axis (L) and linearly movable along the longitudinal axis (L), the plasticizing screw (4) having at least one functional area (5), and - A sensor (6) arranged in or on the plasticizing cylinder (3), with which the distance (D) to the surface of the at least one functional area (5) of the plasticizing screw (4) can be measured, characterized in that a recognition of the type (T) of the functional area (5) and / or the operating state (B) of the functional area (5) is carried out by the steps - Moving the functional area (5) relative to the sensor (6), - Acquisition of a distance signal curve (V), - Compare the detected distance signal profile (Vis) with a stored distance signal profile (Vrer) and - Outputting a signal (S-, Se) representing the type (T) of the functional area (5) and / or the operating state (B) of the functional area (5) depending on whether the detected distance signal profile (Visı) corresponds to a stored distance signal profile (Vrer ). In addition 9 sheets of drawings