GB2046152A

GB2046152A - A Molding Machine

Info

Publication number: GB2046152A
Application number: GB8010038A
Authority: GB
Original assignee: Acme Cleveland Corp
Current assignee: Acme Cleveland Corp
Priority date: 1979-03-26
Filing date: 1980-03-25
Publication date: 1980-11-12
Also published as: ES489895A0; JPS5623346A; FR2452341A1; ES8101951A1; DE3010694A1

Abstract

A molding machine for molding foundry molds or cores and intended for use with a non-free-flowing mold material 71 is provided with a restrictor 48 and a distributor passage 56 in a distributor 54. The material 71 may be a mixture of sand and a binder, which binder may be cured by an admixed catalyst or by a later-supplied catalyst gas. The machine is especially useful where one or more mold cavities 15, 16 are being filled through a plurality of investment apertures 21, 22 and the molding material is not free-flowing and also has a tendency to set or harden. The restrictor 48 is provided downstream of the blow head so that all of the molding material 71 has to pass through the restrictor opening 49. The material 71 then goes into the distributor passage 56 which distributes the molding material to the investment apertures 21, 22, and thence into the mold cavities 15, 16. A clean-out device is provided to clean out any excess material left in the blow head, restrictor and distributor. <IMAGE>

Description

SPECIFICATION A Molding Machine This invention relates to a molding machine, and is particularly, although not exclusively applicable, to molding machines for making foundry molds and cores.

Many foundry mold making machines have been devised to make molds or cores of a molding material, principally sand and a binder. Usually, in such known machines, the molding material was baked or heated in order to harden the binder to have the mold retain the desired shape. In recent years, a thermosetting binder was utilized so that when heat was applied, the resulting sand mold became quite hard. More recently, cold setting mold materials have been used wherein the adhesive in the sand mix was cured by passing a catalyst gas through the molding material within the mold box. In both the thermosetting and cold setting with catalyst gas processes, it was not particularly important to observe any special precautions about the already mixed sand and binder waiting in a sand magazine for the next cycle of operation.Since neither heat nor catalyst gas was applied to such sand magazine, the sand and adhesive mixture therein did not set up or harden. As a result, it was common practice to retain a fairly large quantity of sand and adhesive mixture in the magazine after each filling of the mold box.

In more recent years, there has been a tendency to avoid use of heat in the setting of the molding material within the mold box because this required energy, and also made the molds and the entire mold making machine hot, thereby establishing a safety hazard for workers handling the finished molds. Also in recent years, there has been a desire to avoid use of catalyst gas, since most of these gases are toxic, thus presenting another safety hazard, and the spent catalyst gas must be disposed of in a safe manner.

More recently, self-setting adhesives have been used wherein the sand was mixed with a two-part liquid, a binder, and a catalyst, so that the complete mixture began to set or cure within a matter of seconds, e.g., 10 to 60 seconds. This required different machinery because the self setting adhesive had to be promptly moved into the mold box before it had a chance to set up in the mixer or in the magazine. The formerly used screw-type mixers were usually too slow because the sand and adhesive mixture had too long a transit time within the screw mixer.Also, many machines would fill some kind of a container with a premeasured amount of molding material and this container would then be moved into a blow position wherefrom it was blown into the mold box or core box after being clamped to it, although this took time for the movement of the container and the clamping, and the mixture would tend to set up in the container. Also, because the mixture was usually a sticky mixture due to the liquid adhesive and catalyst, it was difficult to fill the container with a precise amount of molding material and it was difficult to make sure that all of this material was blown out of the container into the mold box. The sand mold might be either a cope or drag mold, or it might be a core for use within the cope and drag mold.

Where it was a core, there was a special problem because if not enough sand and adhesive mixture was applied to fill the core box, then the core would not be complete and would be scrap rather than being usable.

The quantity of molding material blown from the container into the mold box was subject to many variables, including the accuracy of dispensing the molding material from the mixing device, the stickiness of the mixture, and the amount of air pressure available for blowing the mixture into the mold box.

Where one or more cavities are provided in the mold box with a plurality of blow apertures leading to the cavities, the problem was aggravated by the fact that the sticky mixture tended to flow along the path of least resistance.

Those blow apertures and those parts of the mold cavity or cavities which were more difficult to fill established a slower rate of flow, and often the mold cavity would not be filled completely, leaving some of the sticky mixture in the blow apertures. The material tended to set up in those blow apertures and then on subsequent cycles the problem was still further aggravated by this partially set mixture providing still further resistance to shunt the mixture still more through the passageways with less resistance. Thus eventually those more resistant blow apertures became plugged, resulting in improperly filled mold cavities for scrap molds or cores.

It is an object of the invention, therefore, to provide a molding machine which will satisfactorily mold the self-setting or quicksetting mold material in a mold box with plural investment apertures, and which will be repeatable cycle after cycle in production use in the foundry.

According to the invention, there is provided a molding machine having a mold box with at least one mold cavity and a plurality of blow apertures thereinto, a blow head having an air pressure inlet and a molding material outlet and adapted to contain a predetermined quantity of molding material, said blow head and mold box having an investment position of a flow path of molding material from the material outlet to the mold box blow apertures, and blow means connected to supply air under pressure to the blow head air pressure inlet to blow the molding material from the blow head through the blow apertures with the blow head and mold box in the investment position, and wherein a restrictor and distributor is provided between the outlet of said blow head and said mold box blow apertures which restrictor progressively narrows the cross-sectional area of the path of flow of the molding material to a single restrictor area, said distributor distributing the molding material from said single restrictor area to the plurality of blow apertures, and said restrictor having a cross-sectional area less than 10% of the area of the inlet of said restrictor from said blow head.

The provision of the restrictor and distributor in the flow path of the molding material just prior to entering the investment apertures promotes proper filling of the mold cavity.

An embodiment of the invention is described below by way of example with reference to the accompanying drawings, in which: Figure 1 is an end elevational view of the complete mold making machine, Figure 2 is a sectional view of the machine on line 2-2 of Figure 1, Figure 3 is an enlarged, partial sectional view, somewhat schematic in nature, taken generally on line 3-3 of Figure 2, Figure 4 is a sectional view on line 4-4 of Figure 3, Figure 5 is an enlarged, perspective view of the machine in an open condition from the side opposite that view of Figure 2, Figure 6 is an enlarged, perspective view of the machine in a cleanout condition, and Figure 7 is an enlarged, perspective view of a modified diverter usable with the machine.

Figures 1 to 6 illustrate a preferred embodiment of the invention as incorporated in a molding machine 11 having a frame 12 with a mold box mounting means 13. A mold box 14 is mounted on the mounting means 13. The mold box 14 may be one of many different forms, for example, flaskless molding of cope and drag molds using a pattern board with two halves of the pattern thereon.Also, it may be just a single cope or drag mold with a flat plate to close off the cavity, or, as illustrated, it may be a core box having core box halves 1 4A and 14B on mounting means 1 3A and 1job. The mold box 14 has at least one cavity, and in this case is illustrated by one having two cavities 1 5 and 1 6. The cavity or cavities are to form a mold or core, and hereinafter this shall be termed a "mold" whether it is a cope or drag mold, or a core which is being formed.

The mold box 14 is openabie in some manner, and in this preferred embodiment the mold box mounting means 13 includesfourtie rods 17 horizontally disposed, on which the mold box 1 4A is reciprocably movable. The mold box 1 4A is movable on the tie rods 17 by means of a ram 18.

The mold box 14B is mounted in a fixed manner in the mold box mounting means 13, which is fixed to the frame 12. Fig. 1 shows the mold box 1 4A swung to an open position on a pivot 20, for easy removal of the molds.

Fig. 2 of the drawing illustrates the two mold box halves 1 4A and 14B in the closed position having a parting line 19. The mold box 14 has one or more blow apertures, or investment apertures, 21 and 22 leading to the cavities 15 and 16, respectively. In this case, these apertures are disposed at the top of the mold box 14 along the parting line 19.

Some investment means is provided, and in this embodiment raw sand is fed to a hopper 26, and from there directed to a rotary mixer 27. This may be of the type shown in United States Patent No. 3,881,703, wherein a liquid adhesive and a liquid catalyst are supplied through conduits 28, 29, respectively. This rotary mixer 27 has the capability of rapid acceleration and precise control of the flow of the sand, resin adhesive, and catalyst so that a predetermined quantity of sticky, self-setting mold material mixture may be supplied out the outlet 30 of the mixer 27 to a hopper 31, where it falls into a magazine or blow head 33. Alternatively, the mixer may mix a cold setting type of sand and binder which is set or cured by a catalyst gas.

Figs. 1, 2, 5, and 6 better show the details of construction of the blow head 33. A second group of four tie rods 34 is provided parallel to and above the first group of tie rods 17. A movable mount 36 is slidably journaled on these tie rods 34. The movable mount 36 has two vertical rods 37 slidably journaling a carriage 38. This carriage carries the blow head 33 for vertical movement. A pair of fluid cylinders 39 are fixed on the movable mount 36 and the piston rods 40 of the fluid motors 39 are connected to the carriage 38 to provide vertical movement thereof. The movable mount 36 is horizontally adjustable on the rods 34 so that the centerline of the blow head 33 coincides with the parting line 1 9. This is an adjustment during set-up, depending upon the thickness of the mold boxes 1 4A and 148.

The upper portion of the blow head 33 is fitted with a butterfly valve 42 to close the upper part of the blow head after the molding material has been fed into it. A blow valve inlet 43 is provided near the top of the blow head 33 to introduce a large quantity of air quickly for blowing the molding material into the cavities 1 5 and 1 6. Also a quick exhaust outlet 44 is provided near the top of this blow head. Optionally, a fludizing air chamber 45 surrounds the blow head 33 and fluidizing air outlets 46 from the chamber 45 to the interior of the blow head 33 are provided to help move the entire slug of molding mixture.

The blow head 33 is preferably cylindrical and on the bottom of this blow head is secured a conical flow concentrator or restrictor 48. This restrictor progressively restricts or narrows the downward flow of the molding material from the inlet thereof at the bottom of the cylindrical blow head 33 to a restricted area or outlet 49. The cross-sectional area of such outlet 49 is no more than 10 percent of the area of the inlet of this cone, and may be as somali as 0.3 percent of such inlet area. The mold material flow path may be horizontal or at an angle, but is shown as being vertical. It will be understood that the molding machine 11 will be used with many different mold boxes 14 throughout its useful productive life, and the blow head 33 is a means of providing this flow path communication from the magazine 32 to the mold box 14. The blow head 33 is provided with a mold box adapter 51 in order to be able to accommodate any of these changed mold boxes 14. In the preferred embodiment, the mold box adapter includes an upper plate 52 fixed to the bottom of the conical restrictor 48 by stiffening ribs 53. The restrictor output 49 is provided in this upper plate 52. A removable lower plate 54 is secured by screws 55 to the upper plate 52. As shown in Fig. 4, this lower plate 54 is provided with an elongated slot 56, which passes completely through the plate 54. This blow plate 54 is usually custom made for each mold box 14 in order to have the ends of the slot 56 communicate with the blow apertures 21 and 22.

This lower plate 54 may be a simple blow plate having only a single aperture to mate with the restrictor outlet 49, but usually is more complex and is considered a distributor to distribute in two oppositely directed horizontal paths the molding material so that it will flow properly to the blow apertures 21 and 22. A gasket 57 is provided on the lower end of the lower plate 54, and also has a slot to mate with the elongated slot 56. The fluid motors 39 may be actuated to lower the blow head 33 to an investment position whereat the elongated slot 56 mates with the blow apertures 21 and 22. This is the position shown in Figs. 1 and 3, whereas in Fig. 5 the blow head 33 has been raised.

A clean-out device 60 is provided, which includes a diverter 61. This diverter is in the shape of a hollow, open-topped box supported on a tapering conduit 62. The conduit 62 is supported by three rollers 64 so that it is horizontally movable from a disabled or retracted position shown in Fig. 5 to a forward or enabled position as shown in Fig. 6. One of the rollers 64 is springmounted to permit the operating end of the diverter 61 to move slightly downwardly under influence of the fluid motors 39. A flexible conduit 65 is connected to the rear of the tapering conduit 62 in order to provide an escape path for the excess molding material. The diverter 61 has an elongated slot 66 to mate with the longest possible slot 56 in the mold box adapter 51. A fluid motor 68 is connected to reciprocate the clean-out device 60 between enabled and disabled positions.A control means 70 is utilized to control the various movements of the machine parts in the cycle of operation as controlled by the usual limit switches, not shown.

Fig. 7 illustrates a modified diverter 75 which may be used in place of diverter 61. This diverter has an elongated slot 66 the same as before, but has two outlets 76 and 77 at each end thereof.

Flexible hoses 78 and 79 are disposed inside the diverter 75 and lead to the flexible conduit 65, as before. Solenoids 80 and 81 actuate pinch valves 82 and 83, respectively, in the flexible hoses 78 and 79.

Operation The cycle of operation of the molding machine 11 may be described starting at most any point in the cycle, since the cycles are repetitive.

Assuming that the mold box cavities 1 5 and 1 6 are empty, the ram 1 8 is energized by the control means 70 to close the mold box halves 1 4A and 1 4B to establish these cavities. Next, the fluid motors 39 are actuated to move the blow head 33 downwardly until the mold box adapter 51 is clamped on the upper surface of the mold box 14.

Thus, the gasket 57 will seal around the blow apertures 21 and 22. The clean-out device 60 is horizontally retracted at this time. This is the investment position shown in Figs. 1 and 3, whereat the restrictor 48 communicates through the restrictor outlet 49 and the distributor slot 56 to the blow apertures 21 and 22.

Next, the rotary mixer 27 is actuated, with sand, resin adhesive, and catalyst being fed thereto and mixed, to become the molding material 71. This will provide a self-setting molding material which, in many cases, is not free-flowing or is partially sticky and difficult to move because it tends to adhere to practically all surfaces. The molding material falls into the hopper 31 and, through the open butterfly valve 42, into the interior of the blow head 33. The rotary mixer is capable of filling the blow head with an accurately predetermined quantity of molding material in a very short time, depending on the size of the cavities 1 5 and 1 6, e.g., at the rate of over 5 lbs per second. After the mixer 27 has delivered the predetermined quantity, it is turned off. The butterfly valve 42 is next closed to seal the top of the blow head 33.The blow valves are opened to blow air through the fluidizing air chamber 45 and through the blow valve inlet 43. This high pressure air blows the molding material 71, through the conical restrictor 48 and through the distributor slot 56, into the cavities 1 5 and 1 6.

This sudden application of pressure on the top of the molding material 71 moves this molding material as a slug downwardly into the cavities. It passes through the restrictor outlet 49, and since this might be only 1 percent of the area of the blow head 33, the molding material must pass quite rapidly through this restricted outlet. It then divides in the elongated distributor slot 56 into two generally opposite flow paths to the blow apertures 21 and 22. This blowing may be accomplished in less than two seconds, depending on quantity. Accordingly, only a short period of time, in the order of 5 to 30 seconds, has elapsed since the liquid resin and liquid catalyst first contacted the sand to become the sticky molding material before this molding material was invested in the cavities 1 5 and 1 6.

This self-setting molding material may begin to set or cure within 30 to 60 seconds, so the present molding machine accomplishes the desired objective of sufficiently rapid filling of the cavity and emptying of the blow head 33 before the molding material has a chance to begin setting or curing.

In many prior art molding machines, a plurality of channels were provided from the blow head 33 to the plural blow apertures, such as blow apertures 21 and 22. Since these channels were in parallel or in shunt, problems arose. The flowing molding material 71 acts like a fluid, namely, it tends to follow the flow path of least resistance. It seems to have been practically impossible to create parallel channels from the blow head to the blow apertures which were of identical flow path resistance. Where one path was of slightly greater resistance to the flow than another, then this one with the higher resistance inherently had a slower rate of movement of the molding material. This meant that a greater amount of molding material must be in the blow head 33 to keep all blow apertures covered with molding material until the mold cavity is completely filled.With the restrictor 49, the amount of molding material can be minimized.

The rotary mixer 27 has the capability of providing an accurately measured quantity of molding material 71 within about 0.5 percent of the desired quantity. This is by carefully regulating the air pressure, speed, and timing of the rotary mixer and controlling the air pressure on the blow valves providing air to the blow head 33. After the cavities 1 5 and 1 6 are filled, there may be about 0.5 percent excess of molding material 71 in the distributor slot 56 of the mold box adapter 51, namely, that excess will be outboard of the cavity 15 and the blow apertures 21 and 22.

The clean-out device 60 is next utilized. The fluid motors 39 are reversed to raise the blow head 33 to the position shown in Fig. 5. Next, the fluid motor 68 is actuated to move the diverter 61 from the retracted position of Figs. 4 and 5 to the forward or enabled position of Figs. 2 and 6. This enabled position is where the centerline of the diverter 61 is in alignment with the parting line 19 of the mold boxes 14. The fluid motors 39 are then energized to move the blow head 33 downwardly slightly to clamp the gasket 57 onto the diverter 61. This enables the diverter passage within the conduits 62 and 65. Next, a cleaning fluid is moved through the blow head 33, restrictor 48, distributor slot 56, and the diverter 61.In this preferred embodiment, the cleaning fluid is air, and conveniently the blow valves may again be actuated to blow air downwardly to divert any excess molding material 71 through the conduits 62 and 65 to a suitable receptacle.

Thus, the clean-out device 60 is quickly and easily actuated to clean out any excess molding material 71 from the molding machine 11 so that it is ready for the next cycle of operation. To complete the cycle, the fluid cylinders 39 move upwardly to unclamp the diverter 61 and the fluid motor 68 moves the diverter 61 to the left, as shown in Fig.

5. This is the disabled condition or position for the clean-out device 60, so that the flow path for investment of the cavities 1 5 and 1 6 may again be established in the next cycle of operation.

The blow head 33 may also be characterized as a magazine to hold a predetermined quantity of the molding material ready for investment or blowing into the mold cavities 1 5 and 1 6. Where the mixing machine does not mix both the resin and a catalyst into the mixture, but only some form of binder cured by a gas, then the problems of premature setting within the blow head are considerably lessened.In that case, the cycle of operation may be similar in that the diverter 61 is moved to the enabled position during each cycle of operation and clamped between the mold box adapter 51 and the mold box 14, yet in such case, a sealing pad 72 on the bottom of the diverter 61 is that which seals the blow apertures 21 and 22 so that a catalyst gas, for example, may be circulated in a known manner through the mold boxes 1 4A and 1 4B to cure the molding mixture.

Alternatively, in a known manner, the sealing pad 72 may be constructed with gas openings therein so that curing catalyst gas may be supplied through the blow apertures 21 and 22 to cure the molding mixture.

The mold box mounting means 1 3A and 1 3B may also be considered mold carriers which are relatively movably mounted on the frame 12.

Because the restrictor 48 is generally conical or funnel-shaped, it will be seen that it progressively restricts the path of flow of the mixture in two orthogonal directions perpendicular to the generally vertical axis of the flow path. This makes the velocity of the mixture flow increase as it approaches the restricted outlet 49. This in turn helps to assure that the mixture will be delivered to completely fill the mold cavities 1 5 and 1 6 without leaving any voids therein. Even though a catalyst is not used, some resin systems will harden after a period of time. When a gas catalyst is used, the blow head is used in a conventional manner. The blow head is not completely evacuated with each core blown.After repeated cores are blown, some of the resin-coated sand along the walls can have a residence time long enough for the mixture to begin hardening and adhere to the walls. With this invention, the blow head can be periodically completely evacuated to prevent this. This will avoid the need for mechanically breaking out this accumulation. The clean-out device 60 provides an alternative flow path for the molding mixture which remains in the restrictor, blow head, and mold box adapter 51, which alternative path does not flow into or through the mold box 14. The distributor slot 56 has a relatively small dimension parallel to the vertical axis of the restrictor 48 and a relatively larger dimension perpendicular thereto, namely, along the length of this slot 56. This fact, plus the fact that this slot opens downwardly, helps assure that all of the molding mixture remaining within this elongated slot 56 will be blown into the diverter 61 during the clean-out portion of the cycle. This downwardly open slot 56 thus promotes easy cleaning for any partially set up molding material.

If the modified diverter 75 is used with the machine 11, then the solenoids 80 and 81 may be actuated alternatively to pinch or close off the flexible hoses 78 and 79, respectively. This actuation would be during the air blast to clean out the machine and such alternative actuation of the solenoids would assure that first one end of the slots 56 and 66 and then the other end of the slots 56 and 66 would be completely cleaned of molding material.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

Claims

1. A molding machine having a mold box with at least one mold cavity and a plurality of blow apertures thereinto, a blow head having an air pressure inlet and a molding material outlet and adapted to contain a predetermined quantity of molding material, said blow head and mold box having an investment position of a blow path of molding material from the material outlet to the mold box blow apertures, and blow means connected to supply air under pressure to the blow head air pressure inlet to blow the molding material from the blow head through the blow apertures with the blow head and mold box in the investment position, and wherein a restrictor and distributor is provided between the outlet of said blow head and said mold box blow apertures which restrictor progressively narrows the crosssectional area of the path of flow of the molding material to a single restrictor area, said distributor distributing the molding material from said single restrictor area to the plurality of blow apertures, and said restrictor having a cross-sectional area less than 10% of the area of the inlet of said restrictor from said blow head.

2. A molding machine as set forth in Claim 1, wherein said restrictor has a cross-sectional area less than 1% vó of the area of the inlet of said restrictor from said blow head.

3. A molding machine as set forth in Claim 1, wherein said distributor is connected to divide the flow path of the molding material into two generally opposite distinct flow paths to the blow apertures.

4. A molding machine as set forth in Claim 1, wherein said distributor has a single elongated outlet to distribute the molding material in said two generally opposite distinct flow paths.

5. A molding machine as set forth in Claim 1, wherein said distributor includes first and second flat and relatively thin plates, a single aperture through said first plate and communicating with the outlet of said restrictor, and an elongated slot through said second plate communicating with said single aperture of said first plate and adapted to communicate with the plurality of blow apertures.

6. A molding machine as set forth in Claim 1, including a molding material diverter having an elongated passage, means to move said diverter to an operative position adjacent the outlet of said distributor to be in a position to divert any excess molding material remaining within the distributor, and means alternatively enabling a diverter outlet from each end of said elongated passage.

7. A molding machine as set forth in Claim 6, wherein said elongated passage is an opentopped elongated slot to mate with said distributor in the operative position of said diverter, and said alternative enabling means including valve means connected to alternatively enable the two diverter outlets.

8. A moulding machine substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

9. Any novel feature or combination of features described herein.