MXPA99007630A - Plastic bucket and lid - Google Patents

Abstract

A plastic bucket includes at least one undercut (202) adjacent an upper end of the bucket defined by a bucket wall which extends upwardly and inwardly along a diagonal path. An annular, vertical section (204) may be provided at the upper end of the diagonal path. Above the vertical section, the bucket wall extends radially outwardly to create an annular, horizontal flange (206). In addition, an uppermost annular rim (208) may extend upwardly from the horizontal flange and be located approximately midway between inner and outer radii of the flange.

Description

CUBE AND PLASTIC COVER CROSS REFERENCE OF THE RELATED APPLICATIONS This application is a continuation in part of the United States Application Serial No. 08 / 823,193, filed on March 24, 1997; which is a continuation in part of the United States Application Serial No. 08 / 798,511, filed on February 10, 1997, now abandoned; which was a continuation in part of the United States Application Serial No. 08 / 707,746, filed on September 4, 1996, now abandoned; which is a continuation in part of U.S. Application Serial No. 08 / 262,916, filed June 21, 1994, now abandoned.

BACKGROUND OF THE INVENTION Many designs of plastic cups and lids are well known, see for example the following John patents. Von Holdt: Patents Nos. 4,375,948; 4,574,974; 4,512,494; 4,512,493; 4,452,382; 4,380,305; 4,308,970 and 4,210,258. Many containers, such as cans for food, paint or other solvents and chemicals have also been made of plastic, as shown in the aforementioned patents. However, plastic buckets of course do not have the strength of metal buckets, so in many cases, the special designs of the plastic buckets are P1486 / 99MX should be used to obtain, for example, a desired level of tangential resistance over the mouth of the plastic bucket. This tangential strength is achieved in the prior art by somehow reinforcing the mouth area of the plastic cuvette, typically involving an annular portion projecting radially inward, which reinforces the cuvette. However, the buckets of this design typically require a collapsible core for molding, which adds investment and operating costs and also tends to slow the operation. In the same way, collapsible cores are subject to failure and other problems, which also delays the efficiency of the operation. ? In accordance with this invention, a plastic cuvette is provided which does not require fabrication with the use of a collapsible core. At the same time, the cuvette has a convenient amount of tangential resistance, including a bucket of plastic with the shape of a conventional metal can # • for painting. ** DESCRIPTION OF THE INVENTION With this invention, a plastic tray defines an annular rim and a removable lid of plastic. The lid defines an annular, external, peripheral wall, which defines an external wall of an annular recess of the lid. The edge of the bucket occupies the P1486 / 99MX k recess in a sealed relationship, secured with the lid. A main objective of the present invention is to provide a unique design for the upper end of a plastic container consisting of an annular undercut section, an annular vertical wall portion over the undercut section, an annular horizontal overhang on the vertical wall annular and a straight annular flange at the uppermost end of the tray, whose flange is placed approximately centrally with respect to the annular horizontal projection. In a preferred embodiment, the anterior tray is provided with a single undercut section that facilitates its molding and allows it to be molded without the use of a collapsible mold core, preferably by using a mold of the type described in the US Pat. United States 4,375,948. The previous design of the new bucket has been tested with extensive testing to achieve a surprisingly improved tangential strength and stacking resistance. These improved strength characteristics are so important that with this bucket design it is possible to remove all of the outer ribs or rings commonly used to provide tangential strength, such as those set forth in US Pat. No. 3,977,563 and US Pat.

P1486 / 99MX United of Letica 4,349,119. The elimination of all ribs and / or outer rings, as well as the elimination of any internal ribs, provides an exceptionally clean and simple design that is easy to mold and offers numerous advantages for users of such plastic trays. The present invention is not limited to the use of a single undercut, but for most applications which is the preferred embodiment. Definitely, it is preferred to mold the above tray without the use of a collapsible mold core, and my preferred mold is of the type shown in my United States Patent 4,375,948, but other molds may possibly be used in certain applications. The invention is not limited to a design without external or internal ribs, but my preferred embodiment does not have external ribs and preferably does not have internal ribs since my unique tray design provides the desired tangential strength and stacking resistance without the need for increased resistance, which is commonly supplied by the ribs. However, some alternative modalities that employ internal or external ribs will be described herein.

P1486 / 99MX BRIEF DESCRIPTION OF THE DRAWINGS i * With reference to the drawings, Figure 1 is a perspective view of a molded bucket with a lid attached in accordance with this invention; Figure 2 is a fragmentary, enlarged, cross-sectional view through the flange of the tray and the periphery of the tray lid taken along line 2-2 of Figure y. 1; Figure 3 is an enlarged, fragmented, enlarged view of the lid and the upper portion of the tray of Figure 1, showing a porcupine of a peel-off strip; '? Figure 4 is a sectional view longitudinal, enlarged, fragmented of another modality of the tray and lid; Figure 5 is an enlarged, fragmented view of a portion of the cuvette of Figure 4; Figure 6 is a vertical section view taken along line 6-6 of Figure 8, showing an alternative embodiment of the invention, wherein a single undercut is provided at the upper end of the container and a plurality of internal reinforcing ribs are formed in the area of the undermined, but external ribs are not provided as in the above embodiments; Figure 7 is a fragmented, enlarged view showing the upper end of the P1486 / 99MX container of Figure 6; Figure 8 is an upward view along line 8-8 of Figure 7, showing a plurality of internal ribs spaced around the inner wall of the container near the upper end thereof; Figure 9 is a vertical, fragmented section showing another alternative embodiment of the invention with a single undercut at the upper end and with a recess at the upper end of the undercut as shown in the embodiment of Figure 4, are provided internal ribs in the undercut area as in the embodiment of Figures 6-8, without the use of any external ribs in the undercut area, and one of the bale ears is shown to support the molded handle; Figures 10 and 11 are views in lateral and upper elevation of a bowl of the type generally described herein, but showing the addition of a plastic handle, which is molded during the molding operation to mold the bowl; Figure 12 is a fragmented vertical section, showing a preferred embodiment of the present invention that is similar to the embodiment of Figure 4 and also to the embodiment of Figure 9, but does not have external or internal ribs because the design of the bucket meets the necessary resistance without the use of the ribs; P1486 / 99 X Figure 13 is a fragmentary, perspective view showing an interruption or groove formed in the radially outer portion of the horizontal flange formed under the upper flange of the trough; and Figure 14 is a vertical section, broken up along line AA of Figure 13. Now, in order to instruct those skilled in the art with the way of making and using my invention, I will describe it, together with the accompanying drawings and some preferred embodiments of the present invention. fifteen . DESCRIPTION OF THE PREFERRED MODALITIES 9 - with reg ation to Fi ations 1-3. and a plastic tray 10 with a lid 12 attached, the lid and the tray are manufactured by injection molding of known plastic compositions. The cuvette 10 shown consists of an annular edge 14 defining the mouth of the cuvette through which the lid 12 extends. The lid 12, in turn, defines an annular, external, peripheral wall 16, which with the inner, annular wall 18 of the lid and the wall The annular, bridge, defines an annular recess which is occupied by the edge 14 of the tray in a sealed relationship, secured with the lid 12. The outer, annular, wall 16 of the lid P1486 / 99MX also defines a circumferential peelable strip 22, which extends almost completely around the circumference of the wall 16 of the lid or is continuous around that wall and ends at one end with a free handle 24 which is partially enclosed for a space 26, so that the handle 24 can be gripped and pulled to cause the circumferential detachment of the circumferential detachment line 28. Upon removal of the release strip 22, the excess of the outer wall 16 can be pulled out with relative ease to open the lid. The inwardly extending projections 30 are provided in a known manner, are intermittently spaced around the periphery of the lid wall 16 or are continuous around the wall to engage with the bottom edge surface 14 of the tray, as is shown in Figure 2. In this way, after removing the release strip 22, the lid of the tray can be easily opened and reclosed when desired. Additionally, the trough 10 defines a plurality of ribs 32 extending diagonally and outwardly, which are an integral part of the molding of the trough 10 and which intersect with each other in an intertwined relationship. These ribs are placed completely around P1486 / 99 X of the periphery of the cuvette 10 and serve to increase the tangential resistance of the cuvette. Also, the shown tray 10 defines three integral outwardly extending rings 34 that intersect the diagonal ribs 32 and thus contribute to improving the tangential strength of the tray near the edge of the tray. In this way, the trays 10 can be molded which, although made of plastic, can have a tangential resistance that can be compared with metal trays, and are even better than metal trays in their resistance to throw away the lid, when the bucket falls or the like. Fins or vanes 36 may be provided to reinforce the lid 12, as convenient. Also, internal vanes or vanes 38 can be provided to cuvette 10 for a similar purpose of strength. Also, it can be seen that the cuvette 10 defines only a diagonal, annular undercut 39 so that the rings 34 can be provided without exceeding the main diameter of the cuvette. This allows the use of the bucket in conventional filling machinery and the like. Also, this cuvette, whose internal boundary of the undercut 39 is not larger than 6.35 millimeters, or no more than 6% of the diameter of the basin can be manufactured with a mold core that is not collapsible, such as the mold disclosed in the United States 4,375,948. The bucket of the preferred designs as shown, is P1486 / 99MX can bounce from the mold core. With reference to Figures 4 and 5, a molded bucket 10a carries a lid 12a which is generally of a design similar to the previous embodiment except that shown herein. As in the above, the lid 12a defines an external annular wall 16a, which together with the inner, annular wall 18a and the annular bridge wall 20a, defines an annular recess for securing the edge 14a of the tray. In this particular embodiment, the edge 14a of the tray is carried on a flange 40 that extends outwards and is carried with the tray. The rim 40 defines an annular recess 42 in which the lower edge 44 of the annular wall 16a, external to the rim is "hidden" to prevent any person from tearing off the lid 12a of the basin with a screwdriver or the like. In this way, the lid 12a is permanently coupled to the trough 10a until removal of the release strip 22a is achieved. The strip 22a of detachment may be of a design similar to strip 22 of detachment from the previous embodiment. When it has been circumferentially removed by breaking along the line 28a in a similar manner, the portion remaining on the outer annular wall 16a is easily removed either with the fingers or with a screwdriver. The projection 30a extending inward can be continuous and annular, P1486 / 99MX or may be intermittent along the circumference for easier opening of the lid 12a. A single undercut 39a is also provided in the trough 12a, similar to that of the previous mode. This provides a recess in which the fins or ribs 46, which extend in an interlaced manner, are provided diagonally as illustrated in Figure 5. This provides an increased tangential resistance to the trough 12a. Also, a tag 48 can be placed over the interlaced ribs 46 if desired by the automatic label application machinery. The resulting container is tamper-proof due to the required use of a tear-off strip 22a to open it and exhibits good tangential strength to prevent inadvertent launching of the lid when the container falls or the like. Now, reference is made to the embodiment of Figures 6-8, wherein a bucket or container 100 has a wall 102 of the container that slopes inwardly at its upper end, as best seen in 103 of Figure 7. , to provide a unique undercut area shown at 104. In this embodiment, the outer ribs are not formed in the undercut area 104, but internal ribs shown in 106 are provided. Figure 8 shows the P1486 / 99 X internal ribs 106 as generally radial and spaced around the entire inner circumference of the upper end of the bucket or container ^. The upper end of the container 100 is different from the container shown in Figure 2 because it has a recess in the wall of the container over the single undercut, generally shown in Figure 4. In this way, with reference to Figure 7, the wall is inclined inward at 103 to form the recess 104 and then extends upwards again at 108 and then outwardly to form a recess 110. Finally, the wall of the container extends upwards again at 112 to define the open mouth of the container. The recess 110 provides the advantage that it achieves a tangential strength for the upper end of the container. In order to facilitate the molding of the plastic cuvette, in accordance with the present invention, and to avoid the need for a collapsible mold core, it is necessary to limit the extent of the undercut as shown, for example, in 104 of the Figure 7 or at 104 of Figure 9, ie, the amount that the wall showed at 108 of Figure 7 is radially recessed from the wall shown at 102. The deeper the recess, the more difficult it will be to mold the tray without the use of a collapsible mold core. Generally speaking, the magnitude of the P1486 / 99MX undercut should not exceed approximately 5% or 6% of container diameter. For example, with a larger container having a diameter of 304.80 millimeters, it is preferable that the undercut does not extend inwardly by more than about 19.05 millimeters. However, for a smaller container, the undercut should comprise a larger percentage of the diameter. For example, with a container that has a diameter of 50.80 millimeters, it is preferable that the undercut does not extend more than 9.84 millimeters inward. For most containers, it is preferable that the undercut does not exceed 9.84 millimeters, but for larger containers, such as a diameter of 304.80 millimeters, the undercut can extend inwards as much as 19.05 millimeters. The really important advantage of the use of an undercut in the present invention is that by using a single undercut and controlling the extent of the undercut, it is possible to mold the container without the use of a collapsible mold core. Reference is now made to Figure 9 which shows a modality similar to the embodiment of Figures 6-8, with corresponding components identified with corresponding prime numbers. In Figure 9, the container wall 102 is inclined inward at 103 and then upward at 108 'and then extended outward again at 110' to P1486 / 99MX form a recess to increase the tangential resistance, as in the previous mode. The undercut 104 'only has no external ribs, but internal ribs are provided at 106' as in the embodiment of Figures 6-8. The vertical wall portion 108 'is a little longer than in the embodiment of Figures 6-8. In addition, Figure 9 shows one of the two bale ears 122 that serve to mount a handle as described below. A similar bale ear is shown at 124 in Figure 6, the opposite is not shown in Figure 6 due to line 6-6 of section in Figure 8. * Figures 10 and 11 show another embodiment of the container that includes a handle 130 which is connected by pivots to opposite sides of the bowl as shown at 132. The bowl shown in 134 is similar to the external rib embodiments described hereinabove, the main difference being the addition of the 130 handle that can be molded during the molding of the bucket. Reference is again made to the modality of Figures 1-3 and to the modality of Figures 4-5. It should be understood that while ribs 38 projecting radially inwardly are shown only in Figure 2, which is part of the embodiment of Figures 1-3, the description of the embodiment of Figures 4-5 indicates that include the same particularities of the modality of the Figures P1486 / 99 X 1-3, unless otherwise described, so the intent is that the modality of Figures 4-5 may include the ribs projecting radially inward shown in 38 of Figure 2. Now it is done reference to Figure 12, which shows a preferred embodiment of the present invention. In Figure 12, the wall 200 of the top right container is inclined inward at 202 and then upward at 204 and then extended outwardly again at 206 to form an annular, horizontal ridge which together with the section 204 vertical achieves substantial tangential strength and stacking resistance. A vertical, annular, top flange 208 designed to cooperate with a lid (not shown) as shown generally in Figure 2, extends upwardly from annular shoulder 206, horizontal from the radius approximately halfway between the internal radius and the external radius of the horizontal shoulder 206. Figure 12 shows an annular, upper flange 208 positioned approximately midway between the inner radius and the outer radius of the annular, horizontal flange 206. The above approximate location of the flange 208 relative to the horizontal flange 206 is desirable in many applications. However, there is another consideration which is that for optimum resistance characteristics it has been found convenient to locate the upper flange 208 so that the P1486 / 99 X radially internal wall 208 is not radially internal to the radially external wall of vertical section 204. As shown in Figure 12, the radially inner wall of the upper flange 208 is slightly radially outwardly of the radially outer wall of the vertical section 204, which has proven to be in a convenient relative position for the flange 208. In this way , while the flange 208 may be located radially inwardly from the position shown in Figure 12, preferably it should not be located so that its radially internal wall is radially internal to the outside of the straight wall 204. There are no external ribs located in the section defined by the undercut 202, as, for example, in the embodiment of Figure 2. Also, there are internal ribs radially inward of the wall 202 of the undercut as in the embodiment of Figure 2 or in the embodiment of Figure 9. The preferred design shown in Figure 12 is free of internal or external ribs. As previously explained, the design of the trough consisting of the undercut 202, vertical section 204, horizontal ridge 206 and vertical, upper flange 208 provides sufficient unexpected strength so that additional strength supplied by the ribs is not necessary. While the present invention is not P1486 / 99MX limited to a bucket with internal or external ribs, the design shown in Figure 12 that does not have ribs is the preferred modality, since it achieves a clean and simple design, that is easy to mold and that is extremely effective for some Applications such as a gallon paint plastic can. The preferred embodiment shown in Figure 12 has only a single undercut, which makes the tray easier to mold without the use of a collapsible mold core, although the present invention can also be used with a tray having more than one undercut. . It is highly desirable that the angle of the undercut wall 202, i.e., the angle defining the wall with the vertical, be controlled so that it does not exceed 45 degrees. If the anterior angle exceeds approximately 45 degrees, it may not be possible to mold the cuvette without the use of a collapsible mold core, especially if more than one undercut is used as in United States Patent Letica 4,349,119. The angle for the wall 202 is about 30 degrees, as shown in Figure 12 and a preferred range for such an angle is between about 30 degrees and 45 degrees. However, satisfactory results can be obtained by using an angle within the range of 20 degrees to 50 degrees. I prefer a range of 30 degrees to 45 degrees for the angle whose diagonal wall 202 is defined P1486 / 99MX with a vertical. A smaller angle can have certain disadvantages because if it is desired to maintain the depth of the undercut, a smaller angle means that the component of the vertical height of the diagonal wall 202 will be larger and in that case, the straight wall 200 of the tray It will have less height. Since the straight wall 200 is frequently used to carry a label, in some applications it can be a disadvantage to reduce its height significantly from that shown in Figure 12. The general purpose of the undercut is to produce tangential strength and the vertical section 204 combined with the horizontal flange 206 achieves exceptional tangential strength to the degree that allows the elimination of internal and external ribs. As a result, if the angle formed by the diagonal wall 202 were to be reduced with the vertical one, in many cases it would not be desired to significantly reduce the depth of the undercut shown in Figure 12 and since in many applications it is not desirable to increase substantially the vertical height component of the diagonal wall 202, in such applications it is preferred to avoid reducing the angle between the diagonal wall 202 and a vertical one to less than 30 degrees. The combination of the undercut 202, straight or vertical, the annular section 204, the annular, horizontal shoulder 206 and the annular, upper flange 208 located approximately in the middle between the inner and outer spokes.

P1486 / 99MX external of the shoulder 206 achieves surprisingly increased tangential strength and stacking strength. Figure 12 has the actual dimensions of the cuvette shown in inches. The dimensions shown are for a gallon plastic bucket and will change for larger or smaller buckets. While it is clearly shown that the invention is not limited to particular dimensions, the relative positioning and relative dimensions of the structural components 202, 204, 206 and 208 are important and the particular design shown in Figure 12 is considered as an arrangement particularly advantageous. While the lid is not shown together with the preferred embodiment of Figure 12, a cap of the general type including a peel-off strip may be used as shown in Figure 4, although it is not necessary that the bottom edge of the lid of the wall is hidden in the manner shown in Figure 4. Figures 13 and 14 show an interruption or slot formed at 220 in the radially outer portion of the horizontal, annular rim 206. While the slot 220 will create a small amount of recess, it serves the purpose of providing room for fingers to be inserted under the outer wall of the lid for the purpose of removing the lid. In accordance with this, for many P1486 / 99 X applications, the minor reduction in strength caused by the groove at 220 in the horizontal flange 206 is acceptable in order to facilitate manual removal of the lid. Another feature shown in Figure 12 relates to the thickness of the diagonal wall 202 and the vertical wall 204 compared to the outermost wall 200 of the cuvette. As shown in Figure 12, both the diagonal wall 202 and the straight wall 204 are a little thicker than the main wall 200 of the tray. The reason for increasing the thickness of the walls 202 and 204 is due to the recess created by the diagonal wall 202, while being designed to increase the tangential strength, will reduce the stacking resistance. As a result, when the The recess is used to create an essential undercut, it is preferred that the wall 202 and, in some cases also the wall 204, be made with increased thickness compared to the main wall 200 of the tray, for the purpose of maintaining the Stacking In the above manner, excellent tangential strength and excellent stacking resistance can be obtained. There are prior patents that set out designs for plastic trays and that provide different structures for the purpose of achieving tangential strength and stacking resistance. However, previous patents do not expose what P148S / 99MX the present invention and are not extensive in providing the advantages of the present invention, especially with respect to the preferred embodiment shown in Figure 12. The United States Patent Letica 4,349,119 in Figure 5 shows a bucket design with a double undercut, one of them is shown at 75 and the second undercut is shown at 106. The second undercut shown at 106 makes molding more difficult, especially since the angle of the vertical seems to exceed 45 degrees and the structure of Letica is commercially made from a collapsible mold core. In addition, Letica exposes a plurality of rings or ribs 68 and generally, the upper end of the Letica tray differs markedly from the present invention, as can be easily observed by comparing Figure 5 of Letica with Figure 12 of the present invention. U.S. Patent No. 4,524,882 discloses a bucket design with a unique undercut at 15 and the so-called bridge member 18 which presumably provides tangential strength. However, the Buc design fails to include any structure resembling the annular, vertical or straight section shown at 204 of Figure 12 of the present invention, which is located intermediate the wall of the undercut 202 and the shoulder 206. annular, horizontal and cooperating in a way P1486 / 99MX with the tangential strength and stacking strength of the design shown in Figure 12. In Figure 12, the combination of sections 204 and 206 provides an annular, L-shaped structure, which offers unexpected advantages with regarding the tangential resistance. In addition, the uppermost upper end of the bucket of Buc is somewhat different from the design of Figure 12, in that it provides straight flange portions on the radially inner and outer edges of the part 18, as opposed to the design of Figure 12 where there is only one annular flange 208 approximately midway between the radially internal and external portions of annular, horizontal shoulder 206. Also, the Buc patent is only a paper patent and the design shown there has never been used commercially. Another prior art patent is Holt's United States Patent 3,997,563. Figure 1 of Holt seems to show an undercut, although the structure is not shown in the other drawings. The upper end of the Holt tray is completely different from the design shown in Figure 12 of the present invention and consists, in essence, of an annular, straight wall 10, with two rings or ribs 18 on the outside and an upper flange which extends upwards from the radially inner edge of ring 18. There is very little similarity, if that P1486 / 99MX exists, between the Holt design and the design of Figure 12 of the present invention. #, P1486 / 99MX

Claims (26)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property; 1. A plastic cuvette including an annular, straight cuvette wall, terminating at an annular edge to form the open mouth of the cuvette, the cuvette wall having an annular undercut located adjacent to an upper end of the cuvette, the wall of the trough in the undercut extends upward and radially inward along a diagonal path, the wall of the trough generally extends upwardly at the upper end of the diagonal path to form a straight annular section, the the cuvette wall extends radially outwardly at the upper end of the straight annular section to form a horizontal, annular rim; the wall of the basin extending along the diagonal path is thicker than the wall thickness of the basin below the undercut.
2. 2. A plastic cuvette as defined in claim 1, wherein the cuvette has only one undercut and the magnitude of the radially inward movement of the undercut is controlled to allow the cuvette to be molded without the use of a collapsible mold core. .
3. 3. A plastic bucket as defined in P1486 / 99MX claim 1, wherein no ribs or outer rings are formed on the wall of the bucket in the undercut area.
4. 4. A plastic bucket as defined in claim 1, wherein the angle between the diagonal path and a vertical path does not exceed about 45 degrees.
5. 5. A plastic cuvette as defined in claim 4, wherein the angle is between about 30 degrees and 45 degrees.
6. 6. A plastic bucket as defined in claim 1, wherein the annular, straight section has a height that is less than the thickness of the horizontal, annular flange and is less than the length of the diagonal path.
7. A plastic cuvette as defined in claim 1, wherein the annular rim comprises an annular, straight flange extending upward from the top of the annular, horizontal rim, the flange being located approximately halfway between the internal and external spokes of the flange.
8. A plastic cuvette as defined in claim 7, wherein the annular, horizontal rim has a thickness that is at least approximately as large as the height of the annular, straight flange.
9. 9. A plastic cuvette as defined in claim 1, wherein the thickness of the flange P1486 / 99MX horizontal, annular is greater than the height of the straight annular section.
10. A plastic cuvette as defined in claim 1, wherein a groove is formed in a radially external portion of the horizontal flange to function as a finger opening to allow manual removal of a lid.
11. A plastic cuvette as defined in claim 2, wherein no external ribs or rings are formed on the wall of the cuvette in the undercut area, and wherein the annular edge consists of an annular, straight flange that is extends upwards from an upper part of the annular, horizontal flange, the flange being placed approximately halfway between the internal and external spokes of the flange.
12. 12. A plastic bucket as defined in claim 11, wherein the angle defined between the diagonal and vertical path is between about 30 degrees and 45 degrees.
13. A plastic tray as defined in claim 12, wherein a groove is formed in a radially outer portion of the horizontal flange to function as a finger opening to allow manual removal of a lid.
14. 14. A plastic cuvette that includes a ring-shaped, straight vessel wall that terminates at an annular edge to form the open mouth of the cuvette, the cuvette wall has an annular undercut located P1486 / 99 X adjacent to an upper end of the bowl, the wall of the bowl in the undercut extends upward and radially inward along a diagonal path, the wall of the bowl generally extends upwardly in the upper end of the diagonal path to form a straight annular section, the wall of the bowl extends radially outwardly at the upper end of the straight annular section to form a horizontal, annular rim, the annular undercut has no outer ribs or rings formed in the same on the wall of the bucket.
15. 15. A plastic bucket as defined in claim 14, wherein the bucket has only one undercut and the amount of radially inward movement of the undercut is controlled to allow the bucket to be molded without the use of a collapsible mold core. .
16. 16. A plastic cuvette as defined in claim 14, wherein the wall of the cuvette extending along the vertical course is thicker than the thickness of the cuvette wall beneath the undercut.
17. 17. A plastic bucket as defined in claim 14, wherein the angle between the diagonal path and a vertical path does not exceed about 45 degrees.
18. 18. A plastic bucket as defined in P1486 / 99MX claim 17, wherein the angle is between about 30 degrees and 45 degrees.
19. 19. A plastic bucket as defined in claim 14, wherein the annular, straight section has a height that is less than the thickness of the horizontal, annular flange and is less than the length of the diagonal path.
20. 20. A plastic cuvette as defined in claim 14, wherein the annular rim comprises an annular, straight flange extending upwardly from the top of the annular, horizontal flange, the flange being located approximately halfway between the internal and external spokes of the flange.
21. 21. A plastic cuvette as defined in claim 20, wherein the annular, horizontal rim has a thickness that is at least approximately as large as the height of the annular, straight flange.
22. 22. A plastic bucket as defined in claim 14, wherein the thickness of the annular, horizontal flange is greater than the height of the annular, straight section.
23. 23. A plastic tray as defined in claim 14, wherein a groove is formed in a radially outer portion of the horizontal flange to function as a finger opening to allow manual removal of a lid.
24. 24. A plastic bucket as defined in P1486 / 99MX claim 15, wherein the wall. of the cuvette "extending along the diagonal path is thicker than the wall thickness of the cuvette below the undercut, and wherein the annular edge consists of an annular, straight flange extending upwards from the part upper of the annular, horizontal flange, the flange is positioned approximately halfway between the internal and external spokes of the flange
25. 25. A plastic bucket as defined in claim 24, wherein the angle defined between the diagonal and vertical course is between approximately 30 degrees and 45 degrees
26. 26. A plastic tray as defined in claim 25, wherein a groove is formed in a radially outer portion of the horizontal flange to "function as a finger opening to allow manual removal. of a cover. P1486 / 99MX